Questions Show – Running Out of Gravitons and Hitting the Brakes at Light Speed

Another week, another roundup of your questions. This week listeners asked: if forces are communicated through particles, can we run out? If you were traveling at light speed, when would you know to stop? And there’s even more. If you’ve got a question for the Astronomy Cast team, please email it in to info@astronomycast.com and we’ll try to tackle it for a future show.

  • Running Out of Gravitons and Hitting the Brakes at Light Speed
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    If forces are communicated through particles, can we run out?

    If you were traveling at the speed of light, how would you know when to stop to get to the desired destination?

    If the Andromeda Galaxy is moving toward us really fast, would the galaxy look farther away than it really is?

    Does the weak force hold anything together or push things apart?

    If Earth’s magnetic field acts on iron, would a sphere of iron have a different wieght than something else?

    Transcript:   Running Out of Gravitons and Hitting the Brakes at Light Speed

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    Fraser Cain: You know what this show needs?

    Dr. Pamela Gay: I don’t know. What does it need?

    Fraser: More Aliens. [Sigh] Since we don’t seem to have any visiting right now, we’re going to have to find some. SETI is an acronym that stands for the Search for Extraterrestrial Intelligence.

    But there’s more to SETI than just putting up a radio telescope and hoping to catch a glimpse of an Alien television broadcast. Pamela, with SETI – I’m sure people have heard quite a lot about this – people who have seen UFOs and think that they’re being abducted all the time, but there is legitimate Science being done to search for Aliens.

    And that is SETI. So, what is sort of the history of the search for Aliens?

    Pamela: Well it basically occurred to people that we’re sending out radio signals all the time. As we generate television, as we generate radio the signals are traveling out into Space and getting carried off to nearby Stars.

    It’s possible that there are other societies out there, other civilizations out there and they might also be working in radio. They might also be perhaps even shooting laser beams our direction; pulses of radio light in our direction.

    And maybe just maybe we can find those other civilizations by just going out and looking at the nearby Stars that just might be capable of having Planets that support life.

    Fraser: Right so here on Earth we’ve been broadcasting in radio signals for the last 50 or 60 years and those signals are moving away from the Earth at the speed of light.

    So, there is a sphere 60 light years on a side – where the radius is 60 light years – that if you’re inside that ball, that sphere, then you would be able to detect signals coming from Earth.

    If you’re outside of that then our signals just haven’t reached that point yet.

    Pamela: What’s scary is I think we’re both feeling our age because it was in the 1930s it was basically more than 70 years ago that the first television signals went out. So, we’ve been sending things out for a long time and those signals could be now hitting a lot of Stars.

    Fraser: Right, that sphere holds probably hundreds if not thousands of Stars.

    Pamela: And so some of these Stars do have Planets. We KNOW some of these Stars have Planets – we just don’t think they have habitable Planets yet because what we’re seeing is hot Jupiters.

    Fraser: Then in vice-versa, there could be Alien civilizations that have been around for thousands or even millions of years who have been broadcasting like this and maybe are broadcasting through the entire Galaxy. It only takes like 60,000 light years to get from any point of the Galaxy outside. So you can imagine they have a big transmitter and they are able to reach every point of the Galaxy.

    Pamela: In 1960, Cornel University Astronomer Frank Drake – the guy who brought us the wonderful Drake equation to try and figure out how many Alien citizens there just might be out there on Alien worlds – went out and made the first modern SETI experiment called Project Ozma after the queen of Oz from the Wizard of Oz series. He didn’t find anything.

    What I find amusing is one of the Stars he looked at Epsilon Aridante actually has a Planet going around it. So even back then before we knew that there was a Planet there he was out there looking to see if there could be life in that system. He also looked at Calseti and it was a start. Since then we’ve looked at thousands of Stars.

    What makes SETI a reasonable expenditure of money is as you’re out there looking at all of these nearby Stars, you’re gathering data on how these Stars are behaving in radio light. This is data that can be used for scientific explorations as well.

    It’s not completely a waste of telescope time. It is telescope time that is spent going “okay, radio quiet, okay, still radio quiet.” But we’re learning the characteristics of all of these different Stars in radio light.

    Fraser: What exactly is a SETI researcher looking for?

    Pamela: In general what you’re looking for is a burst of intensity that you’re scanning across the Sky listening to Bland radio Star, Bland radio Star and then all of a sudden you see a signal that’s either higher intensity or has a pattern to the signal that’s coming off of it that’s not just noise.

    Television signals, radio signals, all of these have modulations in the signal that your radio and television are able to turn into voices, music and pictures. As you’re listening to these Stars, what you’re looking for is changes in the modulation of the radio that are not nonsense, not white noise but have statistical significance. You can then go “aha, this just might have meaning” and try and come out of it, tweeze out of it with some sort of a coherent signal. The question is as we start thinking about perhaps we can start sending signals out and help our own Planet be discovered, what sort of signals might we be looking for? Anyone who has paid attention to how they encode the new Hi-Definition Television Signals knows that there’s been all sorts of arguments over how do you encode it; how do you phase the data.

    Anyone who has done graphics knows that there’s multiple ways to compress an image. Once we find something that looks coherent, it’s going to be a matter of reverse-engineering the format of essentially this intergalactic file that has been sent towards us.

    Fraser: Right, okay if you point your radio telescope at a Star today – even the Sun – you’re just going to get a sort of a cracking popping random fluctuation that should stay within a very normal parameter, right?

    Pamela: Tune your radio or television to a channel that doesn’t exist. What you experience is what we get when we look at something that is giving off white noise.

    Fraser: And so, if there was some kind of intelligent signal happening then it might still sorta seem like white noise but there will be a pattern to the noise that will say “okay, there’s no possible way that nature generated this pattern.”

    Pamela: Right, we’ll get something that we may not understand but we know this isn’t completely random. You can imagine someone rolling 8 different weighted dice.

    You’re going to notice that “wow, these don’t behave quite right” but if you’re mixing up which dice is which one each roll, it’s going to take you awhile to sort out how the 8 different dice are weighted.

    Fraser: Okay, so what does the modern search for extraterrestrial intelligence look like?

    Pamela: SETI has been forced to struggle. It used to be that they were funded in part by NASA. Now they’re completely funded through private donations. Since 1994 NASA hasn’t spent any money on the search for extraterrestrial intelligence. They’ve only spent money on astrobiology which is basically the search for extraterrestrial microbes.

    What the SETI Institute out in California has done is they work to raise money to build the Allen array a radio telescope system that is going to be dedicated strictly to the search for extraterrestrial intelligence. There has also been other one off projects.

    For instance Harvard has a project that is piggy-backing on the back of one of their optical telescopes and as the telescope goes about doing its normal research this instrument that’s mounted on top is looking for pulses of laser light that might be coming from other Stars.

    Fraser: That strikes me as crazy that there’s no Science funding for this search. I mean it’s kind of like THE most important question you could possibly ask scientifically.

    Why is that? Why is there not official backing and the poor folks at the SETI Institute have had to go and do pledge drives and raise money from private individuals.

    Pamela: It’s politics. Far too many things come down to that very simple sentence. It’s politics. There are crazy people out there – many of us know some of them – who believe they’ve been abducted by Aliens, they believe they’ve been probed. They believe things that we have no scientific way of testing to say “yes you are right” there’s no evidence to say “yes you are right”.

    These people have given the entire Search for Extraterrestrial Intelligence Program a really bad rap. So when Congress is out there and Senators and Representatives are trying to get on their high horse and say that we’re spending money appropriately, they will often go through NASA, the National Science Foundation, and the National Institutes for Health expenditures and start pulling out things that have names they can make fun of.

    For instance, when I was at McDonald Observatory, we had a project called HEMP which stood for the Hobby-Eberly Telescopes Echo Mapping Project. It was a project to map the cores of Galaxies with actively feeding Black Holes. They saw the name HEMP and the project almost got cancelled.

    Fraser: Hmm… Poor naming choice.

    Pamela: Yeah. So, SETI – Search for Extraterrestrials, little ETs – that’s easy to make fun of sort of the way McCain has been making fun of the Adler Overhead Projector. The name and what’s being funded – well what’s being funded is significant. You can name something silly and make fun of it.

    Fraser: Okay so before I interrupted you, we were talking about the Allen Array. How does the Allen Array work?

    Pamela: The Allen Array is still in the process of getting built. It was formerly called the One Hectare Telescope. It’s paid for by Paul Allen which is where the name comes from. It’s in northern California.

    This system is going to have 350 radio dishes on it that work together. It’s made as much as possible with off the shelf technologies to keep the price low. You can sort of imagine they went out and bought 350 satellite dishes that you might use to get old style pre-dish network, back yard satellite signals for your television. They have all of these commercially available dishes.

    They’ve strung them together in their own miniaturized – but with more scopes – version of the very large array. This allows them to collect a lot of signals. It also means that they’re going to be able to have higher resolution. It means that they’re going to be able to if they want to, tune their dishes to a lot of different frequencies and it also means that they have a lot of redundancy.

    There was one signal caught once called the Wild Signal. It was caught with one telescope and only one of the two detectors on that one telescope was able to catch it at moment. We don’t know if that one signal was real; if it was a fake or if it was something from the Earth or Space.

    With the Allen telescope they will be able to say “yes, this signal was caught by this many telescopes; it was caught this different set of frequencies with all sorts of different types of coverage” and it will allow a better sense of what is real and what isn’t.

    Fraser: If Astronomers have been searching for signals from Extraterrestrials for 30 years, why haven’t they found anything yet? I mean I think maybe that is where the funding is getting cut.

    You’ve been at it for 30 years, how hard is it [Laughter] just to point a radio telescope up at the Sky and point it at all the different nearby Stars and call it a day.

    Pamela: So here where I live in rural Southern Illinois, we don’t have a channel 2. So if I have a television that I bought in Boston where we did have a channel 2, and I came out here and every knob except for channel 2 on my television was broken, I would conclude that there is no intelligence producing television in Southern Illinois.

    And I’d be wrong. The problem is I’ve only done my experiment on one narrow channel. As we search the Sky for signals, for all we know they could be using any one of hundreds and hundreds of different radio frequencies. So we have to look at all of these different frequencies.

    Not only that, but the Sky is a really big place. We have to search all these different Stars and all these different frequencies. We haven’t been doing it continuously for 50 years. The first attempt to detect something was made in 1960. We’ve been hit or miss doing it now and then with this scope and that scope as time is made available.

    There hasn’t been a search of the entire Sky in even one frequency. There are all these different frequencies that we can try looking in. There’s a lot of Space and we’ve only probed a small part of it.

    Fraser: Right so there’s the problem, right? There are hundreds of millions of Stars in the Milky Way and you would have to watch each Star on every single frequency – because you don’t know what frequency the Aliens would be broadcasting on.

    Pamela: And you’d have to do it more than just once. You can imagine someone looks in the direction of the Planet Earth and the moment in time that they capture corresponds to the moment in time that we were behind the Sun.

    So you have to go back more than once to really rule out a Solar System and look for more than a brief instance. All these pieces together means this is a project that’s going to take a long time for us to do.

    It’s something that has to be done in both the northern and southern hemisphere. The Allen telescopes can at least get us the northern hemisphere. But that’s still only half the Sky.

    Fraser: If I remember and I was trying to dig this up before the show and I was unable to find it but Seth Shostak who works at the SETI Institute said that it would take something like the Allen Array or even something bigger working for a few dozen years to do a comprehensive search in the radio spectrum for all the Stars that are appropriate within a certain range of us to really say okay we’ve searched the radio spectrum and we haven’t found any signals. We’ve really right now just scratched the surface.

    It’s almost like decoding the human DNA on one person and now you’ve got to do everybody else. Or like finding Asteroids, NASA feels pretty confident that they have located most of the Planet-killing Asteroids and plotted their locations.

    But there are still millions of potentially dangerous Asteroids out there that they haven’t even found yet. It’s just scratched the surface of this project.

    Pamela: The thing that you always have to wonder about is once you’ve done all of this work in the radio, well what if you’re dealing mostly with societies that never developed radio. What if you’re dealing with societies that went straight to encoding things in microwaves and doing point-to-point communications?

    Fraser: So are there any plans to search for that kind of thing?

    Pamela: Not that I know of but that doesn’t mean they don’t exist The problem with point-to-point communications is it doesn’t exactly leak through the Atmosphere so here you have to start hoping that we’re having signals beamed toward us.

    Fraser: Right I think with SETI the expectation is that we’re not eavesdropping on a civilization that’s just broadcasting television shows. There is a very advanced civilization that has a lot of energy at its disposal and is pumping a lot of that energy into broadcasting a signal out so that it can be heard on another Star. Right?

    Pamela: This is one of the things that I actually find really remarkable. If you use the right color of laser and you focus it using basically a 10 meter telescope – something like the very large telescopes that they have down in Chile – you can focus a laser beam such that a Planet orbiting another Star detects it will see for a brief moment that laser beam appear a thousand times brighter than the Sun.

    So, it actually makes sense for us to not just – if we want two-way communications – to not just go out and listen but to also be beaming signals as we go. It’s kind of a waste of a 10 meter telescope to dedicate it strictly to shooting laser beams out to other worlds, but you can almost imagine a system that observes a Star, observes a Star, discovers a Doppler-shifting Planet and then says “ah, found you!” and beams it with a laser beam briefly.

    Fraser: So are people searching for these beamed laser beams?

    Pamela: There is a program at Harvard University – the one I mentioned earlier – that’s piggybacked on their Optical Telescope and it’s out there looking at thousands of Stars just paying attention while the telescope is off doing its own Science looking for these potential laser beams from other Worlds.

    Fraser: So it’s exactly that, right? We’re hoping that some Alien species has found us, knows that there’s a civilization here and is occasionally zapping at us with a laser beam to see if we’re paying attention.

    Pamela: And even though the Sky is a really big place to try and explore, we can actually increase the probabilities of success on these active projects by looking at how we discover Planets. The places in the Sky that people are most likely to realize “wait that Solar System over there has Planets.” And the places that are most likely to try and actively send us signals are on a very narrow band around the Sky.

    The way we detect Planets is we look for Doppler-shifting of the Sun. With the Sun to be the Alien Sun in this case to be yanked around by its largest Planets causing it to have these wobbles in its motion that we detect a slight variations to the red and blue of individual spectral lines. We also look for Eclipses. We look for the hot Jupiters to pass in front of their parent Star and cause the light to dim in some cases just a hundredth of a magnitude. But we can see these slight changes and if we look at the parts of the Sky where Aliens on Alien Worlds would see Jupiter Eclipsing our Sun would see our Sun’s wobble at its most pronounced due to all of the Planets pulling on it.

    Those are the places that are most likely to know about us if they’re finding Planets the same way we are. We can focus our energy quite literally on shooting laser beams and shooting radio signals at those potential Worlds and increase our odds of having this actually work.

    Fraser: The assumption would be that those Worlds would be doing the same. It’s almost like if we can find Earth-sized Planets around other Stars, then we start zapping at them and we can almost assume that they’re going to be zapping at us. We would do a much better search of those Worlds than some random Red Star. We talked about radio mostly. We’ve talked a little bit about optical. Are there any other ways that maybe civilizations are attempting to communicate?

    Pamela: Well, one way – and we’ve actually done this a bit ourselves – that you can try and communicate to other species is you just send them your junk. Not literally, but if you think about it by the time Voyager One and Voyager Two which both contain information about the Planet Earth on them, by the time they reach other Solar Systems they’re going to be a bit beat up.

    They’re going to no longer really be functioning and just sort of traveling through Space as very technologically advanced pieces of scrap metal. But it didn’t take a lot of energy to put those systems together. As they explored our Solar Systems they did a lot of really great Science. They served a purpose.

    Now they’re just on their way outside of the Solar System. Someday they might get scooped up by an Alien race and they’re carrying a lot of information with them encoded on records and engraved on their surfaces.

    Fraser: I’ve heard that it will take whatever, 77,000 years for the Voyager Spacecraft to reach the nearest Star. If you’re an Alien civilization that’s maybe been around for millions of years, what’s a few tens of thousands of years to do some communicating.

    You can imagine a civilization just going with the absolute lowest amount of energy possible and just hurling very clever little robots in all directions. One per Star and the robot lands and then just starts communicating.

    Pamela: You have to wonder is this a really good way to use resources right now but once we start being able to easily mine the Asteroid Belt, it starts to become much more feasible to think about sending little chunks of rock out in all directions carrying some sort of message.

    This is where we have to start thinking carefully about what sort of signal do we want to send. How do you communicate with someone that isn’t going to have the same basis of language? How do you communicate numbers? There are a lot of very intelligent people from many different fields who’ve gotten together at different points in time to figure out how to encode things.

    What I love most is one of the things that was sent on the record on one of the Voyager missions – I don’t remember which – was the sound of a beating human heart. These are just fascinating things that we’ve decided are representative of our World that we wish to communicate.

    The way that we always come down to settling on how we are going to communicate is with mathematics. So hopefully, some things truly are universal.

    Fraser: Right but I think that if we found an object, we would know right of way that it was made from an Extraterrestrial Intelligence. You wouldn’t necessarily need to communicate but if it was made of something or had properties that we had never seen before.

    Even something sent from our future, like if you sent something made out of Carbon Nanotubes or even things that we’ve only developed in the last ten or twenty years, it would be very indicative to people here that someone else made this. We don’t have this technology yet.

    We talked about Matter being sent, there’s one article that we did on Universe Today a little while ago about civilizations using Neutrinos to communicate.

    Pamela: This is where you have to start getting the civilizations far more advanced than our own. We’re just figuring out how to detect Neutrinos effectively. The idea of communicating effectively with them is still beyond us.

    We know that you can get bursts of Neutrinos from extremely distant sources. Then it just becomes a matter of trying to figure out how to send these things that don’t weigh a lot so if you move it very close to the speed of light that don’t get absorbed really – these things don’t like to react via the electromagnetic spectrum – so you can basically shoot them through Planets and Stars.

    How do you effectively communicate with them and code information in them? Especially with the way they change varieties at will it appears.

    Fraser: Right but as we mentioned these are the nearly massless particles that are streaming out of the Sun right now.

    We mentioned that Neutrinos would go through nearly a light year’s worth of solid lead before finally getting stopped. If you had a way to generate them – I mean don’t we generate Neutrinos in Nuclear Reactors here on Earth?

    Pamela: Right, so we know how to generate them fairly easily. The problem that we have is figuring out how to detect them consistently. You can imagine that you can basically send out smoke signals with Neutrinos where you get bursts of Neutrinos coming through.

    You’re able to detect those bursts of Neutrinos and get information out of the size of the burst. Or other ways perhaps that some advanced civilization will figure out how to encode information in these patterns of arriving really tiny particles.

    Fraser: Now, I had two things that I want to talk about before we wrap this show up. One is talk just for a second about SETI at Home which is awesome. It’s been going for quite a few years now. If you have a computer with some idle CPU time you can install this screensaver called SETI at Home which lets your computer help crunch through all of those gigabytes of data that are drawn down by those telescopes.

    And you can search for some kind of signal from an Extraterrestrial Intelligence which is just great, such a great use of your computer time and processor power so don’t e-mail us we know about SETI at home. [Laughter] We think it’s great.

    Pamela: And it’s FREE!

    Fraser: It’s free, yeah. But I think the last thing I wanted to talk about was: “Is it dangerous for us to be sending signals out into Space?”

    Pamela: I think this is where we start getting into Philosophy and it comes down to the question: “Do you really want to find Aliens?” If the answer is yes, then are you worried that they might be dangerous?

    I’m not so much worried about other Aliens coming and destroying the Planet Earth. I’m probably a little bit Pollyanna in that. But once we discover Aliens, I don’t know what that will do for our society. I don’t know what consequences that will have philosophically. There are religious implications.

    There are so many different things where you can sort of think of the movie Independence Day where you had people on the tops of buildings offering themselves up to UFOs. You can think of the book “Contact” where you had people lining up at the fences of the VLA and yes these were fictions, but I think in this case you have very intelligent writers that imagined what this sort of a discovery would do in our society that has from everyone from the truly crazy to the truly brilliant.

    Unfortunately it’s not an even distribution by numbers across that. I’m not sure we necessarily want to find Aliens right now. Then there is always the issue of if the Aliens just really want to come and take our resources and turn us into slaves.

    Again, I’m not particularly worried about that being likely. Space is a big place. You cannot travel at the speed of light. We’re a long way from the nearest Star that could potentially have a habitable World. So, I’m not really worried about that.

    Fraser: So, you’re not worried about Aliens coming and stealing our resources and turning us into slaves and so on. It’s sort of like it’s just way too expensive to make that trip. [Laughter]

    Pamela: Yes. Exactly, it’s too expensive.

    Fraser: It’s like buying a super tanker so that you can go across a lake to steal somebody’s lunch.

    Pamela: It is in fact more like the Seinfeld episode where they discovered that there is a ten-cent deposit on aluminum cans in Massachusetts. So they rent a truck, fill it with aluminum cans and try and drive them all to Massachusetts to get their deposits back.

    You’re going to spend too much money on gas. Just stay at home and take them to the recycling facility.

    Fraser: Exactly, go mine another Asteroid. Grow another Space Cow. Okay, but then you are worried that you think that our fragile emotional state can’t handle the comprehension that there is another intelligent species out there.

    Pamela: I admit to thinking there will be momentary mass chaos and far too many organizations forming cults. It’s just not something I’m excited to live through.

    Fraser: But should people hide the knowledge?

    Pamela: No. I’m for full disclosure if you find something. I’m for full scientific honesty and openness.

    Fraser: So you’re just kind of bracing for impact.

    Pamela: Yeah, yeah there’s part of me that thinks this is so cool and we definitely need to keep looking. But if we can hold off finding something until I don’t have to deal with the chaos, I’m okay with that.

    Fraser: And I think there would be no chaos. Not only that, it would become mundane. [Laughter] It would be like BORING. Like do we have to hear about those Aliens again and their Alien TV shows? They’re not very good. [Laughter]

    I think that within a very short period of time it would become a very mundane thing. There are so many amazing things that have already happened that we as human societies have incorporated into our psyches.

    We just kinda like whatever, those cars they drive are really fast and people can fly in the air without wings, that any amazing thing becomes mundane very quickly. So I wouldn’t be worried about it at all. Bring on the Aliens.

    Pamela: But for now, I’m going to maintain that I’m a very strong proponent of WETI and a proponent of SETI but not perhaps strong….

    Fraser: Oh, WETI, that’s right. We’ve totally forgotten to talk about WETI. Let’s talk about WETI which is the [Laughter] last kind of search for Extraterrestrial Intelligence. So what is WETI?

    Pamela: WETI is: Waiting for Extraterrestrial Intelligence. Just sort of hanging out, sitting on your sofa waiting to see if the Extraterrestrial Aliens show up. It’s the effortless action committee is the way they put it. [Laughter]

    Fraser: So don’t build Spaceships, don’t build telescopes, don’t send signals, Matter or build Neutrino detection devices, just sit on your sofa and wait for some Alien to come in and sit down beside you and ask for a beer.

    Pamela: Exactly this is my way of searching for Aliens every day of the week. I am totally a member of WETI and in fact, you can sign up to be a part of their effortless action committee on their website.

    I’m for SETI – they’re getting really good science out of what they’re doing. If we do find Aliens, well okay, but it’s important knowledge. It means something to know if we are or aren’t alone in our Galaxy. We can’t answer that question if we don’t look.

    Fraser: Yeah, I think that if I were in charge of priorities, I would make the search for Extraterrestrial Intelligence one of the highest possible priorities. Personally I would throw a lot of resources at both SETI and things like the Terrestrial Planet Finder which would be searching for Earth-like Planets orbiting other Stars.

    That is the most fundamental important question in Science right now is: Are we alone? To find out, why not just listen and see if we can find them. If we don’t find them, that’s fine.

    That tells us something, that life is rare and that our Earth and our civilization are rare and we have a duty to preserve life and peace and try to help explore the Universe. It’s like if you find out that the Universe is populated with tons of civilizations and they’re all busy then it takes a little of the pressure off of us to keep life going. [Laughter]

    But if we can’t find a signal then I think that means a lot to us and shows that we have a lot of responsibility as a __35:26 race in the Universe to get out there and explore and do our job.

    Pamela: While SETI is out there actively looking for Extraterrestrial Intelligence, NASA through many of its different programs and the Astronomy community through many of its different programs are looking for ways to look for plant life, microbial life and looking at the imprints of just organic life forms affecting the Atmosphere in which they live.

    We’re trying to define new ways as we’re finding these new Planets orbiting other Stars to say yes, that World clearly has something affecting its Atmosphere. Yes there is life out there. I hope we really find that type of life in the next ten years.

    Fraser: And we can so let’s just do it. So stop cutting the Terrestrial Planet Finder.

    Pamela: Yeah, build it and Darwin.

    Fraser: Yes, Darwin. Oh if I could run NASA. [Laughter] All right, thank you Pamela and we’ll talk to you next week.

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    Fraser Cain: You know what this show needs?

    Dr. Pamela Gay: I don’t know. What does it need?

    Fraser: More Aliens. [Sigh] Since we don’t seem to have any visiting right now, we’re going to have to find some. SETI is an acronym that stands for the Search for Extraterrestrial Intelligence.

    But there’s more to SETI than just putting up a radio telescope and hoping to catch a glimpse of an Alien television broadcast. Pamela, with SETI – I’m sure people have heard quite a lot about this – people who have seen UFOs and think that they’re being abducted all the time, but there is legitimate Science being done to search for Aliens.

    And that is SETI. So, what is sort of the history of the search for Aliens?

    Pamela: Well it basically occurred to people that we’re sending out radio signals all the time. As we generate television, as we generate radio the signals are traveling out into Space and getting carried off to nearby Stars.

    It’s possible that there are other societies out there, other civilizations out there and they might also be working in radio. They might also be perhaps even shooting laser beams our direction; pulses of radio light in our direction.

    And maybe just maybe we can find those other civilizations by just going out and looking at the nearby Stars that just might be capable of having Planets that support life.

    Fraser: Right so here on Earth we’ve been broadcasting in radio signals for the last 50 or 60 years and those signals are moving away from the Earth at the speed of light.

    So, there is a sphere 60 light years on a side – where the radius is 60 light years – that if you’re inside that ball, that sphere, then you would be able to detect signals coming from Earth.

    If you’re outside of that then our signals just haven’t reached that point yet.

    Pamela: What’s scary is I think we’re both feeling our age because it was in the 1930s it was basically more than 70 years ago that the first television signals went out. So, we’ve been sending things out for a long time and those signals could be now hitting a lot of Stars.

    Fraser: Right, that sphere holds probably hundreds if not thousands of Stars.

    Pamela: And so some of these Stars do have Planets. We KNOW some of these Stars have Planets – we just don’t think they have habitable Planets yet because what we’re seeing is hot Jupiters.

    Fraser: Then in vice-versa, there could be Alien civilizations that have been around for thousands or even millions of years who have been broadcasting like this and maybe are broadcasting through the entire Galaxy. It only takes like 60,000 light years to get from any point of the Galaxy outside. So you can imagine they have a big transmitter and they are able to reach every point of the Galaxy.

    Pamela: In 1960, Cornel University Astronomer Frank Drake – the guy who brought us the wonderful Drake equation to try and figure out how many Alien citizens there just might be out there on Alien worlds – went out and made the first modern SETI experiment called Project Ozma after the queen of Oz from the Wizard of Oz series. He didn’t find anything.

    What I find amusing is one of the Stars he looked at Epsilon Aridante actually has a Planet going around it. So even back then before we knew that there was a Planet there he was out there looking to see if there could be life in that system. He also looked at Calseti and it was a start. Since then we’ve looked at thousands of Stars.

    What makes SETI a reasonable expenditure of money is as you’re out there looking at all of these nearby Stars, you’re gathering data on how these Stars are behaving in radio light. This is data that can be used for scientific explorations as well.

    It’s not completely a waste of telescope time. It is telescope time that is spent going “okay, radio quiet, okay, still radio quiet.” But we’re learning the characteristics of all of these different Stars in radio light.

    Fraser: What exactly is a SETI researcher looking for?

    Pamela: In general what you’re looking for is a burst of intensity that you’re scanning across the Sky listening to Bland radio Star, Bland radio Star and then all of a sudden you see a signal that’s either higher intensity or has a pattern to the signal that’s coming off of it that’s not just noise.

    Television signals, radio signals, all of these have modulations in the signal that your radio and television are able to turn into voices, music and pictures. As you’re listening to these Stars, what you’re looking for is changes in the modulation of the radio that are not nonsense, not white noise but have statistical significance. You can then go “aha, this just might have meaning” and try and come out of it, tweeze out of it with some sort of a coherent signal. The question is as we start thinking about perhaps we can start sending signals out and help our own Planet be discovered, what sort of signals might we be looking for? Anyone who has paid attention to how they encode the new Hi-Definition Television Signals knows that there’s been all sorts of arguments over how do you encode it; how do you phase the data.

    Anyone who has done graphics knows that there’s multiple ways to compress an image. Once we find something that looks coherent, it’s going to be a matter of reverse-engineering the format of essentially this intergalactic file that has been sent towards us.

    Fraser: Right, okay if you point your radio telescope at a Star today – even the Sun – you’re just going to get a sort of a cracking popping random fluctuation that should stay within a very normal parameter, right?

    Pamela: Tune your radio or television to a channel that doesn’t exist. What you experience is what we get when we look at something that is giving off white noise.

    Fraser: And so, if there was some kind of intelligent signal happening then it might still sorta seem like white noise but there will be a pattern to the noise that will say “okay, there’s no possible way that nature generated this pattern.”

    Pamela: Right, we’ll get something that we may not understand but we know this isn’t completely random. You can imagine someone rolling 8 different weighted dice.

    You’re going to notice that “wow, these don’t behave quite right” but if you’re mixing up which dice is which one each roll, it’s going to take you awhile to sort out how the 8 different dice are weighted.

    Fraser: Okay, so what does the modern search for extraterrestrial intelligence look like?

    Pamela: SETI has been forced to struggle. It used to be that they were funded in part by NASA. Now they’re completely funded through private donations. Since 1994 NASA hasn’t spent any money on the search for extraterrestrial intelligence. They’ve only spent money on astrobiology which is basically the search for extraterrestrial microbes.

    What the SETI Institute out in California has done is they work to raise money to build the Allen array a radio telescope system that is going to be dedicated strictly to the search for extraterrestrial intelligence. There has also been other one off projects.

    For instance Harvard has a project that is piggy-backing on the back of one of their optical telescopes and as the telescope goes about doing its normal research this instrument that’s mounted on top is looking for pulses of laser light that might be coming from other Stars.

    Fraser: That strikes me as crazy that there’s no Science funding for this search. I mean it’s kind of like THE most important question you could possibly ask scientifically.

    Why is that? Why is there not official backing and the poor folks at the SETI Institute have had to go and do pledge drives and raise money from private individuals.

    Pamela: It’s politics. Far too many things come down to that very simple sentence. It’s politics. There are crazy people out there – many of us know some of them – who believe they’ve been abducted by Aliens, they believe they’ve been probed. They believe things that we have no scientific way of testing to say “yes you are right” there’s no evidence to say “yes you are right”.

    These people have given the entire Search for Extraterrestrial Intelligence Program a really bad rap. So when Congress is out there and Senators and Representatives are trying to get on their high horse and say that we’re spending money appropriately, they will often go through NASA, the National Science Foundation, and the National Institutes for Health expenditures and start pulling out things that have names they can make fun of.

    For instance, when I was at McDonald Observatory, we had a project called HEMP which stood for the Hobby-Eberly Telescopes Echo Mapping Project. It was a project to map the cores of Galaxies with actively feeding Black Holes. They saw the name HEMP and the project almost got cancelled.

    Fraser: Hmm… Poor naming choice.

    Pamela: Yeah. So, SETI – Search for Extraterrestrials, little ETs – that’s easy to make fun of sort of the way McCain has been making fun of the Adler Overhead Projector. The name and what’s being funded – well what’s being funded is significant. You can name something silly and make fun of it.

    Fraser: Okay so before I interrupted you, we were talking about the Allen Array. How does the Allen Array work?

    Pamela: The Allen Array is still in the process of getting built. It was formerly called the One Hectare Telescope. It’s paid for by Paul Allen which is where the name comes from. It’s in northern California.

    This system is going to have 350 radio dishes on it that work together. It’s made as much as possible with off the shelf technologies to keep the price low. You can sort of imagine they went out and bought 350 satellite dishes that you might use to get old style pre-dish network, back yard satellite signals for your television. They have all of these commercially available dishes.

    They’ve strung them together in their own miniaturized – but with more scopes – version of the very large array. This allows them to collect a lot of signals. It also means that they’re going to be able to have higher resolution. It means that they’re going to be able to if they want to, tune their dishes to a lot of different frequencies and it also means that they have a lot of redundancy.

    There was one signal caught once called the Wild Signal. It was caught with one telescope and only one of the two detectors on that one telescope was able to catch it at moment. We don’t know if that one signal was real; if it was a fake or if it was something from the Earth or Space.

    With the Allen telescope they will be able to say “yes, this signal was caught by this many telescopes; it was caught this different set of frequencies with all sorts of different types of coverage” and it will allow a better sense of what is real and what isn’t.

    Fraser: If Astronomers have been searching for signals from Extraterrestrials for 30 years, why haven’t they found anything yet? I mean I think maybe that is where the funding is getting cut.

    You’ve been at it for 30 years, how hard is it [Laughter] just to point a radio telescope up at the Sky and point it at all the different nearby Stars and call it a day.

    Pamela: So here where I live in rural Southern Illinois, we don’t have a channel 2. So if I have a television that I bought in Boston where we did have a channel 2, and I came out here and every knob except for channel 2 on my television was broken, I would conclude that there is no intelligence producing television in Southern Illinois.

    And I’d be wrong. The problem is I’ve only done my experiment on one narrow channel. As we search the Sky for signals, for all we know they could be using any one of hundreds and hundreds of different radio frequencies. So we have to look at all of these different frequencies.

    Not only that, but the Sky is a really big place. We have to search all these different Stars and all these different frequencies. We haven’t been doing it continuously for 50 years. The first attempt to detect something was made in 1960. We’ve been hit or miss doing it now and then with this scope and that scope as time is made available.

    There hasn’t been a search of the entire Sky in even one frequency. There are all these different frequencies that we can try looking in. There’s a lot of Space and we’ve only probed a small part of it.

    Fraser: Right so there’s the problem, right? There are hundreds of millions of Stars in the Milky Way and you would have to watch each Star on every single frequency – because you don’t know what frequency the Aliens would be broadcasting on.

    Pamela: And you’d have to do it more than just once. You can imagine someone looks in the direction of the Planet Earth and the moment in time that they capture corresponds to the moment in time that we were behind the Sun.

    So you have to go back more than once to really rule out a Solar System and look for more than a brief instance. All these pieces together means this is a project that’s going to take a long time for us to do.

    It’s something that has to be done in both the northern and southern hemisphere. The Allen telescopes can at least get us the northern hemisphere. But that’s still only half the Sky.

    Fraser: If I remember and I was trying to dig this up before the show and I was unable to find it but Seth Shostak who works at the SETI Institute said that it would take something like the Allen Array or even something bigger working for a few dozen years to do a comprehensive search in the radio spectrum for all the Stars that are appropriate within a certain range of us to really say okay we’ve searched the radio spectrum and we haven’t found any signals. We’ve really right now just scratched the surface.

    It’s almost like decoding the human DNA on one person and now you’ve got to do everybody else. Or like finding Asteroids, NASA feels pretty confident that they have located most of the Planet-killing Asteroids and plotted their locations.

    But there are still millions of potentially dangerous Asteroids out there that they haven’t even found yet. It’s just scratched the surface of this project.

    Pamela: The thing that you always have to wonder about is once you’ve done all of this work in the radio, well what if you’re dealing mostly with societies that never developed radio. What if you’re dealing with societies that went straight to encoding things in microwaves and doing point-to-point communications?

    Fraser: So are there any plans to search for that kind of thing?

    Pamela: Not that I know of but that doesn’t mean they don’t exist The problem with point-to-point communications is it doesn’t exactly leak through the Atmosphere so here you have to start hoping that we’re having signals beamed toward us.

    Fraser: Right I think with SETI the expectation is that we’re not eavesdropping on a civilization that’s just broadcasting television shows. There is a very advanced civilization that has a lot of energy at its disposal and is pumping a lot of that energy into broadcasting a signal out so that it can be heard on another Star. Right?

    Pamela: This is one of the things that I actually find really remarkable. If you use the right color of laser and you focus it using basically a 10 meter telescope – something like the very large telescopes that they have down in Chile – you can focus a laser beam such that a Planet orbiting another Star detects it will see for a brief moment that laser beam appear a thousand times brighter than the Sun.

    So, it actually makes sense for us to not just – if we want two-way communications – to not just go out and listen but to also be beaming signals as we go. It’s kind of a waste of a 10 meter telescope to dedicate it strictly to shooting laser beams out to other worlds, but you can almost imagine a system that observes a Star, observes a Star, discovers a Doppler-shifting Planet and then says “ah, found you!” and beams it with a laser beam briefly.

    Fraser: So are people searching for these beamed laser beams?

    Pamela: There is a program at Harvard University – the one I mentioned earlier – that’s piggybacked on their Optical Telescope and it’s out there looking at thousands of Stars just paying attention while the telescope is off doing its own Science looking for these potential laser beams from other Worlds.

    Fraser: So it’s exactly that, right? We’re hoping that some Alien species has found us, knows that there’s a civilization here and is occasionally zapping at us with a laser beam to see if we’re paying attention.

    Pamela: And even though the Sky is a really big place to try and explore, we can actually increase the probabilities of success on these active projects by looking at how we discover Planets. The places in the Sky that people are most likely to realize “wait that Solar System over there has Planets.” And the places that are most likely to try and actively send us signals are on a very narrow band around the Sky.

    The way we detect Planets is we look for Doppler-shifting of the Sun. With the Sun to be the Alien Sun in this case to be yanked around by its largest Planets causing it to have these wobbles in its motion that we detect a slight variations to the red and blue of individual spectral lines. We also look for Eclipses. We look for the hot Jupiters to pass in front of their parent Star and cause the light to dim in some cases just a hundredth of a magnitude. But we can see these slight changes and if we look at the parts of the Sky where Aliens on Alien Worlds would see Jupiter Eclipsing our Sun would see our Sun’s wobble at its most pronounced due to all of the Planets pulling on it.

    Those are the places that are most likely to know about us if they’re finding Planets the same way we are. We can focus our energy quite literally on shooting laser beams and shooting radio signals at those potential Worlds and increase our odds of having this actually work.

    Fraser: The assumption would be that those Worlds would be doing the same. It’s almost like if we can find Earth-sized Planets around other Stars, then we start zapping at them and we can almost assume that they’re going to be zapping at us. We would do a much better search of those Worlds than some random Red Star. We talked about radio mostly. We’ve talked a little bit about optical. Are there any other ways that maybe civilizations are attempting to communicate?

    Pamela: Well, one way – and we’ve actually done this a bit ourselves – that you can try and communicate to other species is you just send them your junk. Not literally, but if you think about it by the time Voyager One and Voyager Two which both contain information about the Planet Earth on them, by the time they reach other Solar Systems they’re going to be a bit beat up.

    They’re going to no longer really be functioning and just sort of traveling through Space as very technologically advanced pieces of scrap metal. But it didn’t take a lot of energy to put those systems together. As they explored our Solar Systems they did a lot of really great Science. They served a purpose.

    Now they’re just on their way outside of the Solar System. Someday they might get scooped up by an Alien race and they’re carrying a lot of information with them encoded on records and engraved on their surfaces.

    Fraser: I’ve heard that it will take whatever, 77,000 years for the Voyager Spacecraft to reach the nearest Star. If you’re an Alien civilization that’s maybe been around for millions of years, what’s a few tens of thousands of years to do some communicating.

    You can imagine a civilization just going with the absolute lowest amount of energy possible and just hurling very clever little robots in all directions. One per Star and the robot lands and then just starts communicating.

    Pamela: You have to wonder is this a really good way to use resources right now but once we start being able to easily mine the Asteroid Belt, it starts to become much more feasible to think about sending little chunks of rock out in all directions carrying some sort of message.

    This is where we have to start thinking carefully about what sort of signal do we want to send. How do you communicate with someone that isn’t going to have the same basis of language? How do you communicate numbers? There are a lot of very intelligent people from many different fields who’ve gotten together at different points in time to figure out how to encode things.

    What I love most is one of the things that was sent on the record on one of the Voyager missions – I don’t remember which – was the sound of a beating human heart. These are just fascinating things that we’ve decided are representative of our World that we wish to communicate.

    The way that we always come down to settling on how we are going to communicate is with mathematics. So hopefully, some things truly are universal.

    Fraser: Right but I think that if we found an object, we would know right of way that it was made from an Extraterrestrial Intelligence. You wouldn’t necessarily need to communicate but if it was made of something or had properties that we had never seen before.

    Even something sent from our future, like if you sent something made out of Carbon Nanotubes or even things that we’ve only developed in the last ten or twenty years, it would be very indicative to people here that someone else made this. We don’t have this technology yet.

    We talked about Matter being sent, there’s one article that we did on Universe Today a little while ago about civilizations using Neutrinos to communicate.

    Pamela: This is where you have to start getting the civilizations far more advanced than our own. We’re just figuring out how to detect Neutrinos effectively. The idea of communicating effectively with them is still beyond us.

    We know that you can get bursts of Neutrinos from extremely distant sources. Then it just becomes a matter of trying to figure out how to send these things that don’t weigh a lot so if you move it very close to the speed of light that don’t get absorbed really – these things don’t like to react via the electromagnetic spectrum – so you can basically shoot them through Planets and Stars.

    How do you effectively communicate with them and code information in them? Especially with the way they change varieties at will it appears.

    Fraser: Right but as we mentioned these are the nearly massless particles that are streaming out of the Sun right now.

    We mentioned that Neutrinos would go through nearly a light year’s worth of solid lead before finally getting stopped. If you had a way to generate them – I mean don’t we generate Neutrinos in Nuclear Reactors here on Earth?

    Pamela: Right, so we know how to generate them fairly easily. The problem that we have is figuring out how to detect them consistently. You can imagine that you can basically send out smoke signals with Neutrinos where you get bursts of Neutrinos coming through.

    You’re able to detect those bursts of Neutrinos and get information out of the size of the burst. Or other ways perhaps that some advanced civilization will figure out how to encode information in these patterns of arriving really tiny particles.

    Fraser: Now, I had two things that I want to talk about before we wrap this show up. One is talk just for a second about SETI at Home which is awesome. It’s been going for quite a few years now. If you have a computer with some idle CPU time you can install this screensaver called SETI at Home which lets your computer help crunch through all of those gigabytes of data that are drawn down by those telescopes.

    And you can search for some kind of signal from an Extraterrestrial Intelligence which is just great, such a great use of your computer time and processor power so don’t e-mail us we know about SETI at home. [Laughter] We think it’s great.

    Pamela: And it’s FREE!

    Fraser: It’s free, yeah. But I think the last thing I wanted to talk about was: “Is it dangerous for us to be sending signals out into Space?”

    Pamela: I think this is where we start getting into Philosophy and it comes down to the question: “Do you really want to find Aliens?” If the answer is yes, then are you worried that they might be dangerous?

    I’m not so much worried about other Aliens coming and destroying the Planet Earth. I’m probably a little bit Pollyanna in that. But once we discover Aliens, I don’t know what that will do for our society. I don’t know what consequences that will have philosophically. There are religious implications.

    There are so many different things where you can sort of think of the movie Independence Day where you had people on the tops of buildings offering themselves up to UFOs. You can think of the book “Contact” where you had people lining up at the fences of the VLA and yes these were fictions, but I think in this case you have very intelligent writers that imagined what this sort of a discovery would do in our society that has from everyone from the truly crazy to the truly brilliant.

    Unfortunately it’s not an even distribution by numbers across that. I’m not sure we necessarily want to find Aliens right now. Then there is always the issue of if the Aliens just really want to come and take our resources and turn us into slaves.

    Again, I’m not particularly worried about that being likely. Space is a big place. You cannot travel at the speed of light. We’re a long way from the nearest Star that could potentially have a habitable World. So, I’m not really worried about that.

    Fraser: So, you’re not worried about Aliens coming and stealing our resources and turning us into slaves and so on. It’s sort of like it’s just way too expensive to make that trip. [Laughter]

    Pamela: Yes. Exactly, it’s too expensive.

    Fraser: It’s like buying a super tanker so that you can go across a lake to steal somebody’s lunch.

    Pamela: It is in fact more like the Seinfeld episode where they discovered that there is a ten-cent deposit on aluminum cans in Massachusetts. So they rent a truck, fill it with aluminum cans and try and drive them all to Massachusetts to get their deposits back.

    You’re going to spend too much money on gas. Just stay at home and take them to the recycling facility.

    Fraser: Exactly, go mine another Asteroid. Grow another Space Cow. Okay, but then you are worried that you think that our fragile emotional state can’t handle the comprehension that there is another intelligent species out there.

    Pamela: I admit to thinking there will be momentary mass chaos and far too many organizations forming cults. It’s just not something I’m excited to live through.

    Fraser: But should people hide the knowledge?

    Pamela: No. I’m for full disclosure if you find something. I’m for full scientific honesty and openness.

    Fraser: So you’re just kind of bracing for impact.

    Pamela: Yeah, yeah there’s part of me that thinks this is so cool and we definitely need to keep looking. But if we can hold off finding something until I don’t have to deal with the chaos, I’m okay with that.

    Fraser: And I think there would be no chaos. Not only that, it would become mundane. [Laughter] It would be like BORING. Like do we have to hear about those Aliens again and their Alien TV shows? They’re not very good. [Laughter]

    I think that within a very short period of time it would become a very mundane thing. There are so many amazing things that have already happened that we as human societies have incorporated into our psyches.

    We just kinda like whatever, those cars they drive are really fast and people can fly in the air without wings, that any amazing thing becomes mundane very quickly. So I wouldn’t be worried about it at all. Bring on the Aliens.

    Pamela: But for now, I’m going to maintain that I’m a very strong proponent of WETI and a proponent of SETI but not perhaps strong….

    Fraser: Oh, WETI, that’s right. We’ve totally forgotten to talk about WETI. Let’s talk about WETI which is the [Laughter] last kind of search for Extraterrestrial Intelligence. So what is WETI?

    Pamela: WETI is: Waiting for Extraterrestrial Intelligence. Just sort of hanging out, sitting on your sofa waiting to see if the Extraterrestrial Aliens show up. It’s the effortless action committee is the way they put it. [Laughter]

    Fraser: So don’t build Spaceships, don’t build telescopes, don’t send signals, Matter or build Neutrino detection devices, just sit on your sofa and wait for some Alien to come in and sit down beside you and ask for a beer.

    Pamela: Exactly this is my way of searching for Aliens every day of the week. I am totally a member of WETI and in fact, you can sign up to be a part of their effortless action committee on their website.

    I’m for SETI – they’re getting really good science out of what they’re doing. If we do find Aliens, well okay, but it’s important knowledge. It means something to know if we are or aren’t alone in our Galaxy. We can’t answer that question if we don’t look.

    Fraser: Yeah, I think that if I were in charge of priorities, I would make the search for Extraterrestrial Intelligence one of the highest possible priorities. Personally I would throw a lot of resources at both SETI and things like the Terrestrial Planet Finder which would be searching for Earth-like Planets orbiting other Stars.

    That is the most fundamental important question in Science right now is: Are we alone? To find out, why not just listen and see if we can find them. If we don’t find them, that’s fine.

    That tells us something, that life is rare and that our Earth and our civilization are rare and we have a duty to preserve life and peace and try to help explore the Universe. It’s like if you find out that the Universe is populated with tons of civilizations and they’re all busy then it takes a little of the pressure off of us to keep life going. [Laughter]

    But if we can’t find a signal then I think that means a lot to us and shows that we have a lot of responsibility as a __35:26 race in the Universe to get out there and explore and do our job.

    Pamela: While SETI is out there actively looking for Extraterrestrial Intelligence, NASA through many of its different programs and the Astronomy community through many of its different programs are looking for ways to look for plant life, microbial life and looking at the imprints of just organic life forms affecting the Atmosphere in which they live.

    We’re trying to define new ways as we’re finding these new Planets orbiting other Stars to say yes, that World clearly has something affecting its Atmosphere. Yes there is life out there. I hope we really find that type of life in the next ten years.

    Fraser: And we can so let’s just do it. So stop cutting the Terrestrial Planet Finder.

    Pamela: Yeah, build it and Darwin.

    Fraser: Yes, Darwin. Oh if I could run NASA. [Laughter] All right, thank you Pamela and we’ll talk to you next week.

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    Fraser Cain: Hi Pamela. More questions.

    Dr. Pamela Gay: Yes. And they’re getting wilder every week.

    Fraser: Yeah, I can definitely see some themes: Black Holes, Light Speed, so…the theory of everything.

    Pamela: Yeah, we can’t go there. [Laughter]

    Fraser: Well, can we go somewhere near there I think? So let’s tackle them. Here we are another week with another round of your questions. This week listeners wanted to know if Forces are communicated through Particles can we ever run out? And if you were traveling at Light Speed, how would you know when to stop? And there’s even more.

    So if you’ve got a question for the Astronomy Cast team, please e-mail it to info@astronomycast.com and we’ll try to tackle it in a future show.

    The first question comes from Paul Vincent. “One thing that made me think a bit more about the notion that Forces are conveyed by Particles (I guess the math works correctly) and some experiments have given data to support the idea but it seems kinda weird and kind of implausible to me. The notion that Gravity and the other Forces are conveyed by endless streams of miniscule balls that emanate from the Source yet somehow tug an object towards the Source from which the particles emanate seems especially strange. Is there an infinite supply of Gravitons to shoot at objects, do they replenish, and if so, how?”

    Alright, so this is back to our series on the Forces and I guess Gravitons are just theorized while the Particles for the Weak and the Strong Nuclear Force are known. So, if the Forces are firing these communication Particles, are they gonna run out? How do they get back into the particle? [Laughter]

    Pamela: You know, I’ve never really actually thought of this problem this way. This is just an amazing question at a “how does that work-type Physics level”? When you’re just reading the books and accepting the mathematics that you forget to ask. And here the best I can really do is to say for every Force there is an equal opposite Force.

    So if the Sun is pulling on the Earth, the Earth is pulling on the Sun and we’re sending equal numbers of Gravitons in both ways. So equal and opposite implies we’re sending the same amount of stuff in both directions.

    Fraser: Right, but I think if you keep up with the analogy that means that the Sun is receiving the Gravitons from the Earth and absorbing them and then adding them to their Graviton pool.

    Pamela: Yeah. And, at a certain level this is where we also start talking about there’s Energies involved. So there’s a Potential Energy that provides the Sun the Energy to fall toward the Earth, the Earth the Energy to fall toward the Sun. It’s also coming from Gravity. And, all of this adds up to you can be creating these Virtual Particles that are flying back and forth conveying these ideas saying “yes, there’s Gravity over there, fall that direction.”

    It’s messy to think about. When you think about all Forces being conveyed by Particles, we don’t always think about Magnetism, with your refrigerator magnet connecting itself to your refrigerator that is being held there with Photons. Well, where are the Photons? When we start doing the Feynman diagrams and stuff, they’re virtual and they come and go.

    Everything cancels out nicely and it works out in the end that there’s nothing being disobeyed with the mathematics. But it does philosophically leave you scratching your head rather hard. The way I like to think of it is for every Force there is an equal opposite Force so the Universe balances out.

    Fraser: So, in the case of say, a Magnetic Field as you said, it’s being communicated by Photons, but the Photons aren’t going anywhere, right? With the Magnetic Field it’s not like Photons are being shot out in the way that you’d get with, let’s say, light.

    Pamela: Right. These are just Virtual Photons that communicate the Forces there.

    Fraser: Is it also sort of a bit of the analogy falling apart?

    Pamela: What do you mean?

    Fraser: Well, you kinda think of it as little balls being shot out by say the Sun, in terms of Gravitational Force. Is that not a way to sort of think about it?

    Pamela: This is the thing where Quantum Mechanics breaks human brains. That’s what is actually happening. There are actually these little Gravitons that are flying through Space to communicate: “hey, there’s a Planet over here, there’s a Star over here”. That part is actually happening.

    Fraser: Well, I guess in theory, assuming…

    Pamela: [Laughter] assuming we have this part of the theory correct.

    Fraser: Yeah, right.

    Pamela: We’re not going to run out of them. There’s plenty of Energy around. They’re going in both directions. Life is good; we’re not going to run out of them.

    Fraser: Right, but it’s not like they’re being used up at all.

    Pamela: No, they’re not.

    Fraser: Right, right. So it’s not like there is any store the Particles are being pulled from. What about the ones that do have Mass? Like the ones that convey the Weak and Strong Force, those have Mass, right?

    Pamela: Uh-huh. And that’s coming out of the Potential Energies. It just works. I have to admit this is where you start getting beyond what you learn as the type of Astrophysicist that I am. I never had to go into this level of Particle Physics other than to go “oh, okay. The math works. I passed the test. I’m going to run away to a different area of Astronomy as quickly as I can.”

    This is really hard scary mathematics. It does work. Feynman was probably the one who understood this best of anyone who has been able to communicate it. The math is so ugly that we resorted to a language of pictures to start describing it because a picture does, in this case, hold a thousand equations.

    We’re not going to run out. The Energies will take care of themselves. It is actually Particles. They’re just Virtual Particles in some cases.

    Fraser: I’ve got a million more questions, but I think we are way outside of your area of expertise at this point. So I think that solves maybe we’ll hit up a Particle Physicist and see what we can get.

    The next question comes from Andrew Boson I think. “For an object and passengers on a Spaceship traveling at the Speed of Light, time would stop. If time stops for you on board the Spaceship then you pass through all points on your journey at the same moment. So if that’s true, how would you know when to stop your Spaceship to arrive at your chosen destination?”

    Okay, so once again we’ve got a Spaceship going the Speed of Light which is not possible.

    Pamela: Not possible.

    Fraser: Not possible. But Andrew wants the…let’s say you could, feel free to break the Laws of Physics here, make a Spaceship go, would you experience no time?

    Pamela: Yes.

    Fraser: Because that’s what Photons experience, right? Photons have no concept of time.

    Pamela: Right. And so this is where the “you would never know when to stop your Spaceship” comes in. You would essentially live forever. But we can’t do this. You cannot go the Speed of Light people.

    Fraser: I don’t want to hear your Laws of Physics, your skewed Laws of Physics. [Laughter]

    Pamela: You’re welcome to try to burrow into Alternate Dimensions. I’m okay with that one.

    Fraser: Right, right [Laughter]

    Pamela: Just don’t try and go the Speed of Light in this set of dimensions.

    Fraser: Right. But the, the cool thing about it, it’s just a thought experiment. Don’t be so uptight about it. [Laughter]

    The amazing thing is the Photons experience no time, right? A Photon is created and as long as it survives in the Universe there’s no passage of time for it. It is every time it’s ever been and ever will be, right?

    Pamela: Right. And, this is what’s really cool about things going near the Speed of Light is that you start getting Unstable Particles that are formed as something High Energy hits the top of the Earth’s atmosphere. That Unstable Particle should never reach the surface of the Earth, because it takes a certain amount of time to travel from up there to down here.

    But because they’re going so fast, the rate at which the Particle experiences time slows down and so we’re able to experience these Unstable Particles formed in the upper layers of the atmosphere down here at the surface of the Earth because their clock slows.

    Fraser: Whoa. So you mean these Particles should be disappearing? They should just be decaying away, but because they are going so fast they get to survive all the way down to the Earth.

    Pamela: Yeah. And so we know, we have tangible results that tell us this idea that time slows down is real. But you can’t go the Speed of Light so you can’t stop time. Which means all the things that you just wish you could press the pause button on, sorry, going the Speed of Light is not the answer that allows you to actually to press that pause button.

    Fraser: But you could imagine your Spaceship going faster and faster. And the difficulty of putting on the brakes would increase. You wouldn’t even have to go the Speed of Light. You’d have to go some significant fraction of the Speed of Light.

    Pamela: [Laughter] Yes.

    Fraser: And you would zip through the whole Galaxy before you would even notice, right?

    Pamela: And I would have to point out the Energy required to stop your going close to the Speed of Light Spacecraft is rather spectacular itself. And then there’s the whole problem of if you stop too quickly you turn into a messy pulp. So, be careful how you fly in your Speed of Light Spacecraft.

    Fraser: I think this is the great example of why nobody really should want to make a Spaceship that goes the Speed of Light. You wouldn’t know when to stop. You would reach the Speed of Light and then you would move into timelessness, and that would be that. I like that.

    Pamela: It might be a bad thing.

    Fraser: Yeah. That’s a perfect reason to give to people to not try and make Light Speed Spaceships. [Laughter] Let’s move on. I think that’s great.

    Okay, the next question comes from Luke Fielding, and this is also about Andromeda. “My question is if the Andromeda Galaxy is moving towards us really fast, would the Galaxy look further away than it actually is?”

    Pamela: Yes. I love this. This is one of the things that totally broke me in Cosmology. When you ask someone how far away is something, you’re asking many different questions.

    There’s the where was it when the light you were seeing right now left it. There is the where is it right now which we can’t see. And there is where is the point that it was when the light left it relative to where we are right now. And those are three different places. [Laughter]

    Fraser: Three different places! Now you can imagine it as a thought experiment. You could imagine closing your eyes and having a really loud car, like a horn moving towards you with the sound coming off of the car, right? And you’ll hear the sound. That sound is not the sound from where the car was when it honked the horn.

    Pamela: Right, the car has moved.

    Fraser: The car has moved.

    Pamela: And the Andromeda Galaxy is moving seriously fast. We’re seeing light from like a quarter of a million years ago. So, it has had time to move in that time, but the light hasn’t got us yet.

    Fraser: So, it’s almost as if you could then Andromeda would look bigger and brighter than it actually does because the Galaxy is that much closer than it was when the light was given off.

    Pamela: Yeah.

    Fraser: I mean not a lot. A million years is going to take whatever, 5 billion years before it collides with the Milky Way, but…

    Pamela: But it still makes a difference.

    Fraser: Yeah, Astronomers can calculate that, I’m sure. That’s pretty cool.

    Pamela: It’s a homework problem for the students in the audience. [Laughter]

    Fraser: And your poor Physics class.

    Pamela: Yeah, that I’m teaching in E & M right now. It’s for when I teach Kinematics next time.

    Fraser: Right. Hit them with that one. [Laughter]I think that’s great. The next one comes from Julia Onions. It’s a question on the Weak Force. I guess Julia didn’t really understand what is the Weak Force a Force between?

    Does it hold anything together or push things apart? I guess that is something we kinda glossed over a little bit because we say that the Weak Force has to do with Radioactive Decay. But what’s the Force? What’s being held or not held?

    Pamela: And I have to admit this is one of those things that the Force just isn’t quite the way we are used to thinking of it in terms of Forces move things around. Forces hold things together.

    In this case, it’s the Forces causing the identity of the Particle and the Weak Force acting over a distance smaller than a Proton is able to say to Quarks okay, change your identity. So here it’s more Force of Quark changing in nature. Not so much a Force between things.

    This is where it gets kinda weird to think about. But it’s acting over such a small distance where we’re no longer dealing with Particles that we’re used to. We’re instead dealing with the Quarks that make up the Particles we’re used to.

    Fraser: Now, why is it called the Weak Force compared to the Strong Force? We have said the Strong Force is the thing that’s holding Particles together. The Weak Force sounds like it’s completely different. Why are they related to each other like that?

    Pamela: They’re actually not related except linguistically. [Laughter]

    Fraser: Great.

    Pamela: The Weak Force is more closely related to Electro-mechanics than it is to the Strong Force. So you can merge the Weak Force and Electromagnetism into the Electro Weak Force at high enough densities and temperatures. Then, we think maybe kind of if you close your eyes and eat the right thing for breakfast and do a lot of math that you can create a grand unified theory that brings together the Strong Force with the Electro Weak.

    That is the combination of the Weak and the Electromagnetism. We don’t have the evidence to prove that we just have some really pretty math. It’s actually really ugly math.

    Fraser: Right. But the short answer is that the Weak Force defines the nature of the Quarks inside a Particle and doesn’t necessarily hold or push things apart in the way that we think of Magnetism or even the Strong Force.

    Pamela: And then it ends up leading to neat types of things what we call Beta Decay. You get Protons and Neutrons switching identities, and that’s kinda cool. It allows things like Neutron Stars to form.

    Fraser: Okay. I think that helps clears things up. Thank you. I think this is the last one here. This one comes from Matt Goden. Matt had a question on Magnetism verses Gravity.

    “If the Earth’s Magnetic Field acts on iron objects does this mean that a sphere of say, iron with a mass of a kilogram will actually have a different weight with the addition of the magnetic attraction to the Earth than something else that has a one kilogram mass?”

    Pamela: Oh, I love when we start dealing with the words associated with Net Force on an object.

    Fraser: Right.

    Pamela: So this is actually something I can give my students as a homework problem. They are going to hate you Matt, but I like you.

    When we use the word weight, we’re referring to an object that is made up of Atoms that have Mass. Those Atoms all working together are getting attracted to the center of the Earth due to all the Atoms in the Earth acting like one large object that has it’s total Force centered at the center of the Earth.

    So the center of the Earth’s Mass, which is really hard to say, is getting pulled by the center of the human’s mass, and vice versa. The two Forces are equal. We’re more aware of the fact that we’re getting pulled to the Earth than the Earth is getting pulled toward us.

    Fraser: Or in this case, a ball of iron, right?

    Pamela: Right. And that’s weight. That’s what you see when you stand on your bathroom scale.

    Fraser: And so it’s that big trick question, the difference between Weight and Mass. Mass doesn’t change; Mass is how much stuff is inside of you. Weight is what the Force of Gravity is that you feel when you’re near something else.

    Pamela: Now, truth be told, the number that your bathroom scale reads has other things going into it. For instance, the air around you is exerting a Force on you and that leads to a little bit of Buoyant Force on your body that helps hold you up. We’re completely unaware of this sort of stuff.

    Now, if I took you and attached strings to you to the roof and pulled a little bit, not enough to take all the weight off your feet, but enough that you felt 30 percent lighter, the scale wouldn’t know that there were strings attached to you and it would measure a lower weight. So your bathroom scale is actually measuring the Net Force on your body: the sum of all the different Forces: the Force of Gravity, the Force of Strings holding you to the ceiling, Buoyant Forces.

    Say you’re under water while doing this. If I attach a whole bunch of metal belts to you and then lift you up with an electromagnet, all of these different Forces pulling your body into different directions add up to a Net Force on your body that if you’re standing on a bathroom scale it doesn’t know where the Forces are coming from. It registers a weight as your Net Force.

    Now, if I have a lump of metal and it’s in the Earth’s Magnetic Field, the Earth’s Magnetic Field is going to exert a Force on that object. Depending on where you are on the Earth, it’s either going to pull you straight down if you happen to be located straight above the North Pole, depending on the polarization and the Magnetic Field.

    It’s going to pull you towards Siberia at some crazy angle. It could do a lot of different things depending on where you are on the Planet. You’re going to head toward one of the poles. That’s part of the Net Force. Now, the Earth’s Magnetic Field is really, really weak. The amount of an effect this is going to have on your average kilogram lump of metal is not the type of thing a bathroom scale is ever going to notice. But it is a Force that is there. It’s just a fairly insignificant Force that is there.

    Fraser: Right, right. So the answer is yes then. Yeah. So, a kilogram block of iron is gonna weigh more…

    Pamela: Or less, it depends on the polarization. It depends on the orientation of the Magnetic Field.

    Fraser: Right, exactly. You know, think about how two magnets will pull together or push apart depending on how they’re organized. So then are you experiencing a bit of a pull or push from the Earth for the iron in your blood?

    Pamela: Well, it depends on if that iron is magnetized. And if you think about it, your average lump of metal does not have the Magnetic Field embedded in it.

    Fraser: No, but the Earth is magnetized right? If I have a fridge magnet, for it to stick to the fridge, the fridge isn’t a magnet. Yeah. Huh. There you go. So that’s why iron is so heavy?

    Pamela: No it’s not. [Laughter]

    Fraser: No. I know, I know. It’s because it’s so dense. Well that covers the questions that we pulled in this week so thanks for that Pamela, and we’ll see you at the next regular show.

    Pamela: Sounds good. And please don’t try to travel at the Speed of Light.

    Fraser: I won’t. [Laughter]

    9 Responses to Questions Show – Running Out of Gravitons and Hitting the Brakes at Light Speed

    1. Joe Bernacki October 3, 2008 at 10:24 am #

      Hi Fraser and Pamela,

      Eek! I think you guys might have implied that the iron in our bodies is magnetic. This is pseudoscience … the iron in blood comes as individual iron atoms (in heme groups), so you can’t have a bunch of iron atoms coming together and all getting colloquially “magnetized.” This idea opens the door to dangerous quackery (magnet therapy), so I think it would be good for you guys to clarify this point.

      Also, I sent in some question a long time ago. Should I resubmit them for a shot at making the new weekly questions shows, or do you have a big long queue of questions that you’re working through?

      Thanks!

    2. Christian S October 3, 2008 at 8:14 pm #

      @ joe Bernacki. yeah, I was thinking about that too. The iron in the blood is not ferromagnetic – If it was, MRI scans would be pretty dangerous 🙂

      Anyway. Thanks for a great show guys!

    3. David Madison October 4, 2008 at 6:59 am #

      If one object emits a graviton that impacts another and causes the two to move toward each other, then the graviton must have negative momentum. Then this runs afoul of Einstein’s lessons in at least two ways. One is that gravity is not a force, but a change to the shape of distance and time. We should not expect to be able to explain gravity on the basis of a force.

      The other Einstein lesson that does not work with gravitons is energy-mass conservation. If this graviton is capable moving two objects, then it must have energy. If an object emits the graviton, then it must emit energy. If it emits energy, then it must lose the mass which is the same as energy. We are capable of measuring this mass loss should it exist, but we do not see it when look. This therefore disproves the hypothesis that gravitons convey the force of gravity.

    4. Anders October 5, 2008 at 1:20 am #

      David, two things:

      a) Einstein could be wrong. His General Theory of Relativity could be one way to look at it, but not necessarily the correct way. It has happened before.

      b) IIUC, these are not real particles but virtual particles, which allows for all kinds of weird stuff, including breaking the conservation of energy over short periods of times.

      Interesting question about iron and magnetism. Would this mean that a long steel wire would experience magnetic tidal forces?

    5. Andrew October 7, 2008 at 10:02 am #

      One nagging little question that i keep on thinking of is…. you cannot go faster than the speed of light, ok… so if you are in a spaceship, going close to the speed of light, and you throw a ball toward the front of the ship. The ball would be travelling at current speed + thrown speed. What if the ball exceeded the speed of light?! Would it blink out of existance?! Or would your arm blink out of existance since your arm had to exceed the speed of light to throw the ball!? I keep thinking of the old thought that the speed of sound was the limit, then we broke that…. will we some day find out that there is such a thing as a light boom? like a sonic boom but with light?

      • blake.g.d. May 20, 2012 at 12:28 am #

        A sonic boom is a shock wave that propagates from an aircraft or other object which is going faster than sound through the air (or other medium). In subsonic flight air is deflected smoothly around the wings. In supersonic flight this cannot happen, because the effect of the aircraft wings pushing the air ahead cannot travel faster than sound. The result is a sudden pressure change or shock wave which propagates away from the aircraft in a cone at the speed of sound. Objects cannot travel faster than c, the speed of light in vacuum. But for light there is no ether to act as a medium being pushed aside like the air that is pushed by an aircraft. The result is that there is no equivalent of a sonic boom for light moving in a vacuum.

    6. Jasper October 9, 2008 at 6:48 am #

      Andrew, the flaw in your reasoning is that you simply add velocities as if you were in a moving car on Earth. Since you are so close to the speed of light you have to take the relativistic effects into consideration.

      Remember that as you speed up – time slows down. This is where you and a stationary observer are different. Imagine your spaceship being capable of traveling at 99% of the speed of light and that you are on your way from Earth to Alpha Centauri, 4.36 lightyears away. Now, for someone on Earth, it would seem like your travel time takes slightly longer than 4.36 years, but for you it would only take a few minutes!

      So now you are on your way to Alpha Centauri, but you still have to entertain yourself for several minutes until you arrive, so you decide to have some fun with the ball you brought. You get your ball and you throw it to the front of the space ship (incredibly fast) at 6 million metres per second. (2% the speed of light). (You’re throwing it so unrealisticly fast because you are trying to exceed the speed of light.) At the same time an astronomer on Earth, with an incredible telescope, that can see your every move, is looking at you. As you throw the ball you see it moving away from you at 6 million metres per second – really fast, but no where near the speed of light. It doesn’t disappear or create a singularity. You are disappointed. The astronomer on Earth sees you throwing a ball too, but he sees you in slow motion. In the time it takes you to pick up and throw your ball the astronomer has lived a whole year. For him, the ball doesn’t break the speed of light either. Though the cumulative speed of the ball and the space ship is very high, it is still below the speed of light.

      You can calculate the speed of the ball like this:

      w = u + v / ( 1 + uv / c² )
      Where w is the speed of the ball as seen by the astronomer on Earth, u the speed of the space ship, v the speed of the ball as seen by you *on* the space ship and c the speed of light.

      Notice that for whatever speeds u and v (provided they are below the speed of light, as they should be, because at or above the speed of light is not possible) the cumulative speed as seen by a stationary observer is always less than the speed of light.

      Just remember – special relativity says nothing can go faster than the speed of light, ever. If you think something can go faster than the speed of light, time will be distorted to make it impossible.

    7. Mike Corfield October 14, 2008 at 7:18 am #

      Andrew, light booms exist – it is called Cerenkov radiation caused by particles travelling faster than the local speed of light (Nb light slows down when it travels through a medium). it is often seen in cooling ponds around nuclear reactors and is also produced by cosmic rays

      Mike

    8. themondo October 15, 2008 at 10:23 pm #

      I have a question for all of you smarts out there. Does a black hole represent all 4 fundamental forces of nature, in the universe, unified into one ‘super unified’ force because of it’s density and its capability of stopping light. This capability must be faster than the speed of light, however small. So does this not say that faster than light speed is capable, only if a black hole can cause it? What say you all?

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