Questions Show: NorthEast Astronomy Forum (NEAF)

Pamela was lucky enough to attend the NorthEast Astronomy Forum, and while she was there she held a live questions show. And now you get to join in an hear the interesting questions, and Pamela's interesting answers.

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. Please include your location and a way to pronounce your name.

NorthEast Astronomy Forum (NEAF)

What are magnetars?

• Magnetars
• New Insights on Magnetars – Universe Today
• "Death From the Skies: These are the Ways the World Will End" by Phil Plait

Are there neutrino detectors that could predict a supernova?

• Neutrinos – UCI
• Neutrino detectors-  Windows to the Universe
• Large Synoptic Survey Telescope
• Pan-STARRS

If a rocket blew up in Earth orbit, would it destroy part of the atmosphere?

• Teleportation
• Will Rocket Traffic Damage the Atmosphere? – LA Times

How much does the sun affect global warming?

• The sun and global warming FAQ — Stanford U
• There is no Sun Link With Global Warming– Universe Today
• The Current Deep Solar Minimum — Science@NASA
• Global warming on other planets in the solar system — Skeptical Science

What is the present state of gravitational wave detection?

• Gravitational Wave
• LIGO – Laser Interferometer Gravitation Wave Observer
• LISA — Laser Interferometer Space Antenna

How real is dark energy?

• Dark energy — NASA
• Expansion of the Universe – WMAP

Can you explain distances to objects as the Universe is expanding, and will objects at the outskirts of the Universe redshift enough that we can't see it anymore?

• FAQ's in Cosmology — UCLA
• Seeing the Edge of the Universe — Astrobiology Magazine
• Questions about the edge of the Universe — Physics Forums

What is there to understand about convection?

• The Topsy-Turveying of Planets, Stars and Lava Lamps — Universe in the Classroom
• Globular Clusters
• Globular Clusters Older than the Universe — International Reporter

What are the latest advancements in String Theory?

• String Theory
• Standard Model of Particle Physics
• Is String Theory Testable?

What would happen if two stars collided?

• Colliding Stars May Create Black Holes - CNN
• White Dwarfs – Window to the Universe
• Planetary nebula
• R Coronae Borealis — AAVSO
• Cataclysmic Variables — NASA
• M 13

Is there a difference between weightless in deep space and in a plane flying parabolas?

• Weightlessness
• Life In Freefall – National Reseach Council Canada
• Shoot a Cannonball into Orbit – NASA's Space Place

Can you explain Tidal Forces?

• Tidal Forces – Windows to the Universe
• Centripetal Force
• Centrifugal Force

Can you give an update on humans returning to the Moon and going to Mars?

• NASA's Constellation Program
• What a Little Moon Dust Can Do — Wired
• The problems of landing large payloads on Mars; right now we can't do it – Universe Today
• Can People Go to Mars?  Science@NASA
• Space Adventures Offers Private Voyages to the Moon

Download the transcript

Transcript: NorthEast Astronomy Forum (NEAF)

Dr. Pamela Gay: Live from NEAF! Welcome to AstronomyCast. With me this week is a room full of amateur astronomers who are going to stump me live with their questions. So, here’s where I ask: what are your questions?

Audience: How real is dark energy and how much of it is just a construct to fit the math? Is there any chance that future observational crews will change current opinion on that?

Pamela: The question is how real is dark energy? There are lots of things that come out of the math and you have to worry is this a real force. Is this us working in some sort of weird topography where it is just a matter of the geometry of space leads to these things?

With dark energy and this is something we’re still trying to figure out, the idea behind dark energy is when we look far enough back in space, we’re actually looking back in time as well because light takes time to reach us.

As we look further and further back we find that the supernova we can measure the distance to them because we know how much light they give off and so we’re able to figure out the distance to them by measuring how much light we received. It’s sort of like you can tell how far away a motorcycle is by how bright the motorcycle headlight appears.

We can do the same thing with supernova. Then we measure how fast they’re moving which gives us a sense of what is the expansion rate of the universe at different points in time. We look at supernova now and figure out well now how fast is the universe expanding. We look at them further back we get how fast was the universe expanding then. As we look back what we find is the universe actually is speeding up over time.

For reasons that mystify the entire astronomical community starting in 1998 things are expanding faster and faster and faster. As the universe gets bigger the amount of energy it contains also gets bigger at a constant rate. We don’t know why but we can name the phenomena and we named it dark energy.

Depending on how you look at the math you can view this either as a force or as a pressure that for every cubic meter of space pushes that cubic meter outwards. We don’t know what it is. We think that it is some sort of real phenomena. It’s not just a figment of the mathematics. It actually comes out. It is scaling with the universe as the universe gets bigger more dark energy appears.

Beyond its pushing the universe apart, accelerating it apart and beyond it seems to be constant with all of time and constant with volume. That’s pretty much all we can say. So, give us a few years.

We only discovered it in 1998 which means given that some things like convection we’ve been trying to understand for hundreds of years. No one understands convection yet. We’ll get there eventually we’re just not there yet. It is real we just don’t know what it is but it is named.

Audience: Thank you. One question I had listening to a lot of the podcasts, astronomycast even Slacker Astronomy, you talked about how far away stuff is. Something is 10 billion light years away.

Is that an actual 10 billion light years away or it was maybe 7 billion light years away and inflation has pushed it up to 10 billion light years? I guess the question is if you could just explain that a little better.

Also, if something is at the outskirts of what we can see, something is at the farthest limit of how far we can see, is that object really expanding away from us to the point where at some point it is going to red shift so far we won’t see it anymore?

Pamela: Trying to figure out where things are and discuss it in a logical way in astronomy hurts. The problem is we see the light from objects that are moving. They’re imbedded in a universe that is expanding. The light then takes time to reach us.

Essentially we have objects that in some cases 10 billion years ago released light while they were located in one place. The place where they were 10 billion years ago has since moved and they have since moved. When we say we’re looking at a galaxy 10 billion light years away what we’re saying is we’re looking at an object that released its light when it was 10 billion light years away. Where that point of space is now, that’s somewhere different and where that object is now is also different.

When we say this object is the furthest away galaxy we’ve ever seen, it is roughly 13 billion light years away that’s where it was when it released its light. Who knows where it is now. It is much further away because of this wonderful thing called the expansion of the universe. The problem with the expansion of the universe is it is slowly changing how much of the universe we can see.

On one hand every second, because light takes time to reach us, we’re able to see a little bit more of the universe because light has had more time to reach us. The universe is also expanding so that edge is getting carried away from us.

The expansion of the universe is such that it is kind of like raisin bread dough rising where we’re the microbes on a raisin. So the space between Caroline and I is expanding. The space between Caroline and the bleachers is expanding a lot more because there is more space. Both of us see everything as moving away from us because everything is expanding. The space between the two of us might be expanding at a meter an hour while the space between her and the bleachers which is maybe 10 times further is expanding at 10 meters.

All of this gets added together so between me and the bleachers I see that moving away at 11 meters. There are objects far enough away that the expansion of the universe is causing them to move away from me faster than the speed of light. It’s not that they’re moving faster than the speed of light, it’s that this space is expanding and that space is expanding and all the other space is expanding. All of these small expansions add up to faster than the speed of light.

There are objects out there that because of the expansion of the universe we will never ever see. Their light is trying as hard as it can to fly toward us but the space in-between is expanding. It’s like the light is trapped on a mad treadmill where the light is going as fast as it can but the treadmill is carrying it further and further away. We’re kind of stuck.

The amount of the universe we can see right now is pretty much all we’re ever going to be able to see because we’re starting to reach that turning point where the edge is starting to get carried away fast enough that we don’t add to how much of the volume we can see.

In fact eventually, far, far in the future, we’re pretty much only going to be able to see the stuff we’re gravitationally bound to in what’s going to become our local super-cluster of galaxies. That’s a very boring future. We happen to be lucky enough to live in a time where we can see a large enough volume of the universe that we can actually start to understand the way our universe works.

Audience: What is there to understand about convection?

Pamela: [Laughter]. So the question is what is there to understand about convection and the answer is all the details. When we try and understand the insides of stars there are really neat little tiny stars where the entire inside of the star is basically acting like a lava lamp.

You can mix the entire atmosphere of the star from the outside all the way in down to the core just like a lava lamp. Blobs rising, blobs sinking, the hot stuff goes to the surface radiates away its heat, cools off, sinks down to the center. All of this wonderful mixing allows the star to use up all of the material that the star is made of in the process of nuclear fusion.

The problem is we don’t understand the details of how things rise and sink because we’re dealing with basically a lava lamp that is bigger than we know how to handle. All the details of its radiating away energy as it rises you get this amount of mixing. You have blobs that behave in these different detailed ways. We can make estimates and sort of model it in 3-dimensions but we have to make a lot of assumptions.

One of the greatest things that we’ve struggled with is trying to come up with detailed models of what’s going on in the insides of stars. Without these detailed models it makes it very hard to figure out how long the stars live. Most of you are old enough to remember that back in the 90s globular clusters were older than the universe.

All of our observational evidence mixed with our understanding of stellar evolution led us to the rather disturbing conclusion the globular clusters were order of 15 to 18 billion years old. We thought that the universe is 10 to 14 billion years old which is, you can’t have stars older than the universe they live in. It turned out the problem was we just didn’t fully understand stellar evolution.

We’re getting better. We now have globular clusters younger than the universe. Much, much happier they’re order of 11 billion years old now. Without understanding the details of stellar evolution, we can’t accurately understand the objects nearest to us, the stars that make up our galaxy.

Understanding convection is one of the processes that we struggle with the most because you have so much movement, so much radiation, so much mixing of thermal layers, mixing of materials, stuff getting carried up and down. Sometimes one blob overshoots, it is chaos and it is wonderful and computers still die trying to do it correctly. So, we build on assumptions. Someday we’ll get there.

Audience: String theory is the latest craze to try to come to a conclusion about the grand unified theory. What have been the latest advancements in string theory and does it look like we’re headed in the right direction with it? Or have there been some major pitfalls that are looking like maybe this might not be the answer?

Pamela: We actually did an astronomycast episode on things we will never talk about. String theory is one of them because we talk about it is a facts-based journey through what we know and how we know it. Part of that is having testable theories.

String theory according to mathematicians I’ve talked to who aren’t string theorists is very scary ugly, ugly mathematics. String theorists refer to it as very scary elegant mathematics. It is scary mathematics nonetheless.

There are probably about 10 people in the world that fully understand string theory and I’m not one of them. That said one thing I do know about string theory that is a bit problematic is there are lots of different versions of the theory. None of them make testable predictions.

One of the things you need to call something a scientific theory vs. math. You can do lots of cool stuff with math. One of the things that you need to have a scientific theory is for it to make testable predictions. Relativity when it was devised we couldn’t run the experiments. We couldn’t test relativity. We didn’t have GPS satellites. There wasn’t a solar eclipse that particular year.

However, Einstein was able to say if my theory is right you should see these observational characteristics. We’ve seen them one by one by one. Relativity has proven true. We’ve been able to see the bending of light as it goes through gravitational fields. We’ve been able to see the affects that it has on time in the GPS satellites.

Your car GPS machine would not work without relativity. String theory can’t do any of that. String theory can say I have tweaked my equations to match what we see. String theory can say here are some things that are completely unobservable that might be true. That’s outside our realm of being able to say is the field making progress? How do you judge progress when you can’t judge if it is right or not? It is difficult.

There are string theorists who are working very hard to come up with testable predictions. So far the things that they’ve predicted are also predicted by the standard model of particle physics. So, you now have two theories that predict the exact same things which mean you can’t differentiate. They need a testable theory. Once they’re there, then I can answer your question. They’re not there yet. It is a young field.

Audience: What would happen if two stars collided?

Pamela: That’s actually a really good question because sometimes stars do eat one another. There are cases where you can end up with 2 stars slowly spiraling in together. In some cases with what are called white dwarf stars you can end up with 2 stars that used to be a lot like the sun. As they got old their atmosphere mostly blew away and you ended up with planetary nebula.

The very core of the star was left behind, something about the size of the moon but so dense that electrons form a crystal. So take something roughly the mass of the sun make it the size of the moon and then give it a friend with the same density and the same size. As these objects orbit and spiral closer and closer together, the one radiating light on the other can heat them up just like if you get too close to a light bulb it heats you up. This will cause the stars to puff back out.

Eventually it is possible that they can merge together and form a new type of star. There are a few papers not well believed but there are a few papers that say stars like our current aborealis might be a case of this happening. That’s not the mainline theory but that’s one of the things that you can find in the literature. So we do have cases of stars eating one another.

Anytime you have a cataclysmic variable that’s one star EATING the atmosphere off of the other star gravitationally. In theory you can end up with 2 stars just randomly coming through space and smashing into each other but that’s very, very hard to do.

It is sort of like if you can imagine if you have a handful of BBs and your friend has a handful of BBs and you roll them from a distance of 100 feet across a gymnasium floor. What is the probability that any of your handful of BBs and your friend’s handful of BBs across an entire gymnasium is going to collide exactly center to center? The likelihood is pretty close to zero.

When galaxies collide, the separations between the stars are even greater than the separation of those BBs getting rolled across the gymnasium. So the likelihood of stars actually colliding into each other is extremely low. What can happen in really dense environments like globular clusters? M13 is one of the prettiest ones to look at. What can happen in globular clusters is you end up with stars that get really close.

They don’t quite collide but sometimes when you get 3 stars really close together, they gravitationally interact and will actually fling one of the stars almost entirely out of the globular cluster. That’s kind of cool. It’s sort of like a mad game of do-sa-do where three people try and swing around each other’s arms and one of them ends up breaking free and flying off across the floor. That happens with stars and gravity.

Audience: Could you give us a few minutes on the difference between the weightlessness that you experience in deep space or you would experience in deep space and the weightlessness you experience in a jet airplane diving or in orbit around the Earth?

Pamela: One of the problems that we deal with is language is not necessarily clear. When I say that I am a weightless, all that really means is that I step onto a spring scale. The spring scale doesn’t care or react in any way. There is no force pulling me down onto this spring scale. I can achieve this spring scale doesn’t care about my mass state in a bunch of different ways.

I can be in an elevator that is dropping down an elevator shaft. Since me and the spring scale are dropping at the exact same rate, the spring scale doesn’t care. We’re both going to destroy ourselves in a few moments and in the interim it’s not going to tell me how much I weigh. It’s not going to tell me what the pull of the Earth’s gravity on my body onto that scale happens to be.

There isn’t really a difference between me in that elevator shaft plummeting towards certain death – not something I plan to experience – and me being on the space shuttle orbiting around the planet Earth or me on the International Space Station orbiting the Earth. What is happening with orbiting objects is they’re falling and missing the Earth.

It’s sort of like Douglas Adams. Take an object, throw it, it will hit the Earth a few feet away. Throw it harder it will fall and hit a few more feet away. Throw something hard enough and it will fall into the ocean. Throw it even harder and it will fall into Europe. That would be bad. Throw something even further and it will make it all the way around the planet and hit you in the back of the head.

Gravity is pulling it down but its attempt to fly forward is causing it to move forward and fall at the same rate. If you keep throwing faster and faster and faster, you’re eventually going to hit Mars or something like that. That’s really interesting. But you have to throw something hard enough to escape the Earth’s gravity.

So when you’re on the International Space Station or on the space shuttle or something like that you’re just falling around the Earth. You and your scale are falling at the same rate and your mass isn’t registering on the scale. There’s no force pulling you onto the scale because you’re both falling at the same rate. If you go out into deep, deep space or even not that deep space if you’re kind of hanging out between Mars and the asteroid belt, this will work too.

As you orbit around the sun in this case now you’re falling around the sun. The scale still doesn’t care. If you go out between the solar systems now you have our sun, you have other stars you have the Milky Way all pulling on you but now you’re falling around the Milky Way. The scale still doesn’t care. All that matters to appear weightless is you and the scale are both falling at the same rate.

What happens on the planet Earth is my fall is getting stopped. Right now the planet Earth is trying really hard to pull me to my knees. But I have muscles and skeleton and things like that so when I step onto the scale there is a force pulling me and that pull is getting stopped. What it is measuring is the normal force; the force that is needed to prevent me from falling through the scale.

Without that normal force without the ground pushing back, the scale pushing back you can’t measure how much I weigh. Anytime you’re falling and the thing that you’re trying to weigh yourself on is falling there’s no balancing of the forces so you appear weightless. It’s just a matter of what are the forces and how are they balanced.

Audience: Since you’re talking about centripetal and centrifugal force the phenomenon of tides on one side of the world vs. the tides on the other, there are several explanations. Let’s hear your thinking on it. [Laughter]

Pamela: Tidal forces are one of those things that I think causes every teacher of physics the first time they teach them to cry. It’s not intuitive. What’s happening is we have big happy planet Earth that we exist on.

If you got rid of everything else that was exerting a force on the Earth, the oceans would just settle down into a nice sphere where their surface would be exactly the same everywhere on the surface of the Earth assuming the density of the Earth was the same everywhere.

It’s not, the ocean is not actually flat because there are differences in density beneath it and all sorts of craziness that goes beyond the scope of anything that anyone but like geologists worry about. The thing is we have this moon and we have the sun and they’re both exerting their own gravitational pull on the Earth and on the oceans.

Right now even though you don’t realize it you’re going up and down as the moon passes overhead. Even the rocks of the Earth, even the crust of the planet flexes in response to the pull of the moon. On the side of the Earth closest to the moon we experience this as getting pulled up toward the moon, high tide. That one is easy to understand. The only problem is how many high tides a day are there? A bunch of people are raising their fingers and saying two. That’s entirely right we get two high tides a day.

One high tide is when the moon is almost straight overhead. It’s not when it’s actually straight overhead because the whole planet is rotating so we get pulled up and carried away. There is offset. Ignoring rotation in the planet Earth the high tide would be directly underneath the moon. In the other high tide is on the exact opposite side of the planet, 180 degrees around away from the moon. That other tide is occurring because the gravity is less.

When you’re at the midpoint, gravity is halfway pulling on you from the moon halfway from the Earth. You have neither high nor low tide. No, you do have low tide, sorry. I started to say that stupidly. You do have low tide at this point.

Then as you keep going around the planet the gravity gets less and less and less. The planet is like ha-ha I don’t need to be compressed. So from the lessening of gravity on the other side when you vectorally add together all the forces doing the sum with little arrows you end up with high tide on the other side of the planet as well.

Near the object, away from the object; high tide in the mid-point, low tide there’s really pretty – I hate doing this but I’m going to send you to Wikipedia where there is a really good vectorial drawing of this.

Audience: Another quick question, what is a magnetar?

Pamela: Magnetars are another one of those things that have only recently been discovered. Recently is being defined as things that have occurred within my memory. Where you have a neutron star which is take a star several times the mass of the sun make it the size of Manhattan Island. These are little tiny, tiny objects. They’re the same thing that pulsars are made out of and they can be rotating very, very fast.

Anytime you have charge rotating you have the ability to build up a magnetic field. The sun’s magnetic field comes from having charged particles. Earth’s magnetic field comes from having charged particles all rotating in a consistent direction.

With magnetars you end up with really high rotation rates, lots of charged particles. I don’t understand the details of the physics. This is another one of those anytime you want to completely foil an astronomer you can ask them either how do magnetic fields affect that or how does dust affect that. They’ll turn white.

Magnetars are a case where you end up with neutron stars with extremely powerful magnetic fields. With the sun we get coronal mass ejections when the sun’s much, much smaller magnetic field rearranges itself, when a field line breaks and reconnects in a different place.

This can cause badness on the planet Earth. For instance we had the Canadian power grid taken down a few years ago during a solar maximum by a coronal mass ejection disturbing the Earth’s magnetic field.

A few years ago a magnetar on the other side of the galaxy, on the other side of the center of the galaxy, had a rearrangement of its magnetic field that released gamma rays powerful enough that they went through the sides of spacecraft. It was like looking at the sun with a CCD.

This is gamma rays going through the side, not through the front where the light is supposed to go in. There were a few things that got slightly damaged in the process. These have powerful enough magnetic fields that if we had one on this side that went off like that it could like destroy our whole atmosphere.

I recommend going and looking at Phil Plait’s book “Death from the Skies”. Bob has it at Astronomy To Go. Magnetars can totally destroy the Earth if they’re close enough. The nice thing is there aren’t any. Basically they’re little tiny stars rotating fast with really powerful magnetic fields that are very hard to calculate.

Audience: We know that all astronomers would love to predict a supernova. [Laughter] One way is that before supernova occurs you have the radiation of neutrinos. Are they doing anything now to actually sense this throughout the world so someone can say hey here comes a supernova?

Pamela: We do have neutrino detectors scattered randomly all across the planet usually in very deep old mines that have then gotten filled with heavy water. Detecting neutrinos is hard and the problem with neutrinos is they really don’t like to interact with normal matter.

One of the candidates for part, not all but part of dark matter is actually the neutrino. You can shoot a neutrino through I think it is a light year of lead and it will happily go out the other side. When we do randomly or at least with low probability but on a regular basis detect neutrinos it takes a lot of work. We can with fair amount of accuracy and regularity say aha, I see a supernova and then go back and find the evidence of the supernova in the neutrino results.

In real time it is hard to do because it takes too much time to analyze the data, follow what’s going on and to directly figure out so we had one set of detections in Japan, another set in Canada, let’s work out the delay times.

Now you have to have all the observatories working in real time together to figure out where in the sky even if you could figure out the ability to tell with the very few neutrino-detecting places on the planet where in the giant sky the supernova went off.

We’re much better off just looking at all of them on a regular basis. Projects like the Large Synoptic Survey Telescope, Pan-Starrs, all of these survey telescopes looking is faster. But we can see the neutrinos, just usually afterwards.

Audience: If a rocket blew up right above me in the atmosphere right before it left Earth’s orbit would there be like a gap in the atmosphere?

Pamela: So how many people here watch Battlestar Galactica or Star Trek? A lot of the hands went up! One of the things they got really wrong with the old version of Star Trek is every time someone teleports out there should be a giant pop because where that human being used to be suddenly is going to get filled with air. You’re going to have this rushing inwards of air.

On the new Battlestar Galactica where they went to light speed from within an atmosphere, that causes the entire atmosphere to suddenly rush into that space. If I just have like happy spacecraft that has an unfortunate moment and opts to blow up in the atmosphere, it is still all there. It won’t leave a gap in the atmosphere because the pieces just sort of fly all over the place.

If we ever had transporter technology every time we teleported someone to a different place you’d end up with a sudden rush of air. So, if I’m standing next to my computer – which I cherish greatly – and Scottie beamed me up, this would fall over.

The pedestal my computer is on would fall over from the vacuum that is created where my molecules used to be and they just got somewhere and all the air whooshes in. It’s with can’t do this in reality transporter technology that you end up with weird things happening in the atmosphere. It’s kind of cool.

Audience: In global warming how much is our sun playing a part?

Pamela: That’s a highly controversial question. It depends on which solar physicist you believe. The data that I’ve looked at and the solar physicists that I’ve talked to up at Rutherford-Appleton Research Station in the UK who work with the STEREO Mission have all said our sun is currently at a stage where it is not increasing in luminosity and it itself is not increasing the temperature of the planet Earth.

Any of you who like to look at solar spots also know that our sun is resolutely refusing to come out of solar minimum. All of this leads to less solar radiation so that it should be a minimal impact on global warming. The caveat is that when you look at global warming on other planets we do see evidence here and there of global warming on other planets.

When you see that evidence you have to take into consideration is it because they’re at part of their orbit that carries them closer to the sun? Their orbits are just long enough that you compare their warming trends and our warming trends and they haven’t completed an orbit.

I’ve had several people come up to me and say but there’s global warming data for other planets. I haven’t had a chance to compare any of that data to the data for the planet Earth.

I don’t know how legitimate that data is and I can’t really address the question other than to say the solar physicists I’ve talked to who are experts say no, it’s not playing a role.

Audience: What is the present state of gravity wave detection and its relation to early supernova detection prior to the supernova event itself?

Pamela: One of the really cool things about gravity is you can actually set up ripples in space and time when big enough events occur. When a star explodes, when two black holes merge and these ripples as they pass through the planet Earth will cause the planet to contract and expand along the direction of the gravity wave.

This is sort of like what would happen to a soap bubble that got compacted by the water it was in having a compression wave move through it or sound waves moving through the air with normal soap bubbles probably make more sense as an analogy. We’re trying to detect gravity waves. We’re trying really hard.

There are a set of facilities around the planet called LIGO. There are several of them where the idea is they have laser light that goes back and forth along extremely long channels. Then it interferes at the end and any change in length will cause the pattern that you see from the light interfering to change.

This has been going on since the early 90s and we still haven’t detected anything but we have a lot of if a supernova happens nearby we won’t detect at levels of how nearby. So far any of the supernova that have occurred haven’t detected them which is sad.

The problem is that these ground-based systems have to deal with trucks driving by which do exert gravity. They have to deal with large amounts of water changing the gravitational pull of nearby mountains. They have to deal with plate tectonics shifting everything. They have to deal with just the general rumble of it’s an active planet that still has volcanoes and things like that.

What we really need is to complete a mission called LISA which is to put a series of gravitational wave detectors up in outer space where you don’t have to worry about the UPS driver. Unfortunately this is one of those NASA missions that just keeps getting delayed and delayed and delayed. No one quite knows when it is going to finally get built. We hope to do this.

The nice thing is that while we haven’t directly measured any gravity waves, we’re pretty sure they exist because we see the radiation. We see the energy the waves would contain getting carried away in binary systems that contain black holes. We see the dead stars, black holes, the neutron stars, black holes and black holes getting carried closer and closer together.

The only way to explain that is if we have gravitational waves radiating away the energy. We’re pretty sure they’re there. We’ve given out the Nobel Prize for the gravitational radiation. We just haven’t directly detected gravity waves yet. But we’re trying. Technology takes time. I think I have time for one more question.

Audience: Can you distill politics from reality and give us an update on what the status is of returning to the moon and for Gods sake, they’re even talking Mars. [Laughter] And it’s probably all just talk now, but what do you know about it?

Pamela: It’s not just the United States that’s planning to go back. It’s the United States, China, India, Japan and Russia. All of them at various levels are planning to go back to the moon either with humans or with spacecraft or with both. There are international treaties in place to do things like build communications networks, set up outposts. We’re starting to worry about the legal repercussions of having multiple nations colonizing the moon essentially.

Contracts have gone out to build a new set of rovers, to build the new sets of spacecraft, to build even the new sets of spacesuits. One of the craziest things of research they’re doing is they’re taking pig skins and potential space shirts and trying to figure out what material to make shirts out of that when they get imbedded with lunar dust cause people to get their skin abraded the least.

Lunar dust makes like beach sand seem friendly. If you’ve ever had beach sand in your clothing, imagine something a thousand times worse and you’re starting to understand what it would be like for astronauts to have the moon dust in their clothing.

Current prognostications are saying we’ll probably start landing people late 20teens early 2020s. I think it is probably going to take a little longer than that for the United States to get there because we have to rebuild all of our launch pads. We have to build and test the Constellation spacecraft. We’re starting everything with the manned space program over from scratch.

We have international treaties that promise that we’re going to continue working on the International Space Station. We’re spread across many different things. With so many nations working together to try and make this a reality I think that for at least the younger people in the room it’s safe to say we will have human beings walking on the moon again within our lifetime.

The plan is once we get to the moon, we’ll go to Mars. That is a bit trickier because we don’t know how to deal with cosmic rays. We don’t know how to deal with radiation. Once we’re there we’re not quite sure how to get them back necessarily because of the energy loads. There are ways to do it, they’re just exceedingly expensive and we don’t know how to pay for it more than we don’t know to do it.

Until we figure out how to very effectively and cheaply and with low weight protect astronauts from radiation I’m not sure getting to Mars is tractable. It is something that is on the books. I think I can say with certainty, moon we’re going to get there. Mars is much more questionable.

The thing is the commercial space race is also starting to be enthused. Once you start getting the Pan-Ams of outer space going, I think your commercial wallets are going to drive space exploration the same way that building larger and higher flying aircraft was motivated by wanting to get Americans flying up above the weather where it was safer.

If any of you have seen the movie ‘The Aviator” advances in many of the aircraft were motivated by how we get human beings comfortably flying into space. We’re starting to get there too. We have Virgin Galactic. We have Bigelow. We have all these different commercial programs that want to take you into space.

That’s eventually what’s going to pay to make all of these dreams a reality. I’m afraid to be nice to the people that are coming on after me I need to wrap this up. Thank you all for being such a great audience.

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