Last week we talked about knowledge, what we do and don’t know. This week we talk about questions which are impossible to ask, where the answers don’t actually exist.
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Announcer: This episode of Astronomy Cast is brought to you by Swinburne Astronomy Online, the world’s longest running online astronomy degree program. Visit Astronomy.SWIN.edu.au for information.
Fraser Cain: Astronomy Cast episode 405, Method Not Found. Welcome to Astronomy Cast, our weekly fact-based journey through the cosmos where we help you understand not only what we know but how we know what we know. My name is Fraser Cain. I’m the publisher of Universe Today and with me is Dr. Pamela Gay, a professor at Southern Illinois University, Edwardsville and the director of Cosmo Quest. Hey Pamela, how you doing?
Pamela Gay: I’m doing well. How are you doing?
Fraser Cain: Good. When I say the director of Cosmo Quest, that really means a lot these days. How are things going with Cosmo Quest?
Pamela Gay: I’ve become far more of a paper pusher than I ever meant to become. I always wanted to be that person out there doing things but now I’m the person out there enabling other people to do things, which is satisfying because there’s people with jobs and stuff. But, wow, paperwork, wow. All of you out there who are career managers and bureaucrats, you’re doing, like, God’s work.
Fraser Cain: Yeah, I have a whole army that surrounds me to handle the paperwork because if I didn’t it would just pile up like snowdrifts in my house.
Pamela Gay: Yeah, yeah. So, yeah, it’s going well. We still have a data management position open. And the reason that it’s still open is mostly because we’ve been so busy getting subcontracts out to all of our collaborating institutions that we haven’t had a chance to look at job applicants yet. So if you are a baby PhD looking for your first post doc, we may have one for you.
Fraser Cain: Right on.
Pamela Gay: Yeah, CosmoQuest.org/X/open-jobs
Fraser Cain: That sounds great.
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Fraser Cain: All right. So last week we talked about knowledge, what we do and don’t know. And this week we talk about questions which are impossible to ask, where the answers don’t exist, where the data can’t be found. And really, we wanted something that would line up with an obscure error code in Apache. So we forgot to do the 404 but we got the 405 in there so I think that’s what really matters.
Okay, Pamela. So let’s move on then to our seeking knowledge to places that just – you shouldn’t even ask a question.
Pamela Gay: Well, it’s not that you shouldn’t ask the question. It’s that when you ask the question, the universe responds with method not found. There’s just some questions that we don’t have the ability – not because of lack of technology, that was last week – but we don’t have the ability because of the nature of the universe to find the answer.
Fraser Cain: Okay. So let’s go with one that I think people are familiar with. They’ve heard it before and this is this idea of the uncertainty principle. Because this is a great example of one where your attempt to find the answer will mess up the answer. You’re just – you’re wrecking it. So let’s talk a bit about how that works.
Pamela Gay: So the uncertainty principle says that you can either know where something is or how fast it’s going but you can’t know both at once. And this isn’t, again, one of those limitations on how well we can measure things. This is a fundamental issue in the universe where the relationship between where something is and its momentum, there’s a constant in there and you just can’t have – you can’t have zero uncertainty.
Fraser Cain: So what happens? Like as you’re trying to measure one, what’s happening to the other one? So if you were in the lab – I’m sure this has been backed up in the lab in credible detail – the better you measure the momentum, what happens to the position?
Pamela Gay: It’s not that something happens to the position so much as the techniques that allow you to know one with the fundamental way the universe works don’t allow you to get at the other one simultaneously. You basically can’t get there from here.
Fraser Cain: And so if you measure one with incredible certainty like its position or its momentum, that other question –
Pamela Gay: — becomes [inaudible] [00:05:34] –
Fraser Cain: — becomes a field of probability that you can’t address.
Pamela Gay: Yeah.
Fraser Cain: If you switch over to the other one, the other one becomes this field of uncertainty that you can’t address.
Pamela Gay: Right.
Fraser Cain: So what if you measure one and then you quickly move over to the other one and you measure the other one?
Pamela Gay: Well, the sucker’s in motion so since it’s in motion you can go from quickly knowing one to quickly knowing the other and the uncertainty still is there. So mathematically what we’re looking at is the uncertainty and how well we know the position multiplied by the uncertainty in how well we know the momentum is always going to be greater than some constant that happens to be H bar over two. It’s just a number.
Another way of looking at it is velocity is how a lot of people look at it but because relativistic stuff can be involved, you need to use the momentum equation because the mass is tied up in there as well. So even though you may always hear position and velocity, it’s really position and momentum, just to get tricky with you.
Fraser Cain: That’s good. Now it saved you probably a hundred letters so that’s perfect. Centripetal, centrifugal, centripetal, centrifugal. So, right, but I think what’s really important, right, is you mentioned this thing, it’s not your tool. Your techniques aren’t great and your tools aren’t great and you really, really work at it and you make the most perfect laboratory with the most perfect measurements with the most perfect equipment. There is a place you can never get past.
Pamela Gay: Right. And this has to do in part with the wave particle reality of our universe where you have to factor in the fact that even stuff is really a wavelength. And where exactly is the center of a wavelength? Even you and I have our own intrinsic wavelengths. It’s just for us, as we talked about a million episodes back, the size of our wavelength is smaller than our body
But when you start looking at these little tiny particles, their wavelength is not all that different from their particle size, or at least what we imply is their particle size. And so you’re kind of stuck trying to figure out how to untangle the center of that and the velocity at which everything is traveling. And quantum mechanics says, no. It just says no.
Fraser Cain: And that’s gotta feel just, I don’t know, [inaudible] [00:08:12] –
Pamela Gay: Why? Why does this bother people?
Fraser Cain: — for some people. It bothers people. Okay. So, I mean, this was sort of the – and we’re gonna come back around to this, right. We’re gonna get to the place where you go, where you as our counselor tell us there will be things that we can never know and we need to be all right with that. But we’ll get to that as we sort of approach the end of this episode. Let’s move to another place that we – in that sort of same category as the what’s outside the universe question.
Pamela Gay: Okay.
Fraser Cain: What’s outside the universe? What’s the universe expanding – and we did a whole episode about this but I think, you know, I’ve had to explain it a hundred times. I’m sure you’ve – so let’s sort of like come back around as we explain why, again, that is a kind of question that you cannot find the answer to.
Pamela Gay: And here the issue is, there’s no method to see outside of our space time continuum. And there’s no physics to say that there would be a method to see outside of our space time continuum. As far as we know, our space time continuum is complete unto itself and it’s kinda like we live on the surface of a balloon with no hope of burrowing through the surface or jumping off of the surface. We’re just stuck here.
Fraser Cain: My favorite explainer on this is called No Edge. And it’s – oh my god, I forgot his name. It’s from – it’s an alien from Beetlejuice on YouTube. And the video’s called No Edge. And he explains sort of that it’s kind of like a video game like Asteroids where you go from one side of the screen to the other side of the screen.
And so if you increase the size of the screen in Asteroids, you just keep scrolling around, whether you go off the top of the screen or whether you go off the left-hand side of the screen, right. Like, what’s outside the screen in Asteroids? There’s nothing. So just do one more dimension, right?
Pamela Gay: Yeah.
Fraser Cain: So just go – imagine if you’re in Asteroids and you go towards you in the game and you pop out on the back of the screen and you keep moving back forward or go the other way, right. And so if you expand that, you can make it bigger and you can travel further but it’s still a finite volume of space that has no outside. You can never get there.
Pamela Gay: Yeah, it’s okay.
Fraser Cain: Yeah, and that –
Pamela Gay: I’m just gonna keep saying that a lot this episode.
Fraser Cain: It’s okay. It’s all right. We can know the solve. And that if it is outside the universe, it’s Zod from Beetlejuice. That’s it, Zod. Zog, Zog, yeah. A bunch of people to check on that. Yeah, Zog from Beetlejuice. It’s a great series and I highly recommend you search this up on YouTube.
And then this idea, right, that if it’s outside the universe but you could measure with the laws of physics of our universe then it’s, by definition, part of the universe.
Pamela Gay: And so there’s just no method to see what’s outside of our universe.
Fraser Cain: What about before the universe?
Pamela Gay: We don’t even really have a way to see before 300,000 years ago so, yeah – no, there’s no method. There are methods to see –
Fraser Cain: You mean 300,000 years after the big bang.
Pamela Gay: That’s what I meant, yes. Wrong direction.
Fraser Cain: Yeah, right. But again, right, if the laws of physics time and space were instantiated at the beginning of the universe, then to ask what came before the universe doesn’t make sense. Okay. This is starting to not feel okay, Pamela, so –
Pamela Gay: Why?
Fraser Cain: Because we understand this concept of before, that we as human beings intuitively understand that for every time there is a before, how can you have a time when there was no before?
Pamela Gay: Why does there need to be a time that was before?
Fraser Cain: Because for all the times that are there’s always been a before.
Pamela Gay: So you’re assuming that time is continuous and doesn’t just stop. But if you were a photon you’d never experience time at all.
Fraser Cain: But how could a something come from nothing, right? Like how – what – why did it decide to begin then, right?
Pamela Gay: It’s – and these are things that we don’t have a method to determine. It’s just there is no method to determine that.
Fraser Cain: So what do you mean when you say there’s no method?
Pamela Gay: So there is a way for me to get the coffee cup off of the surface of my desk. I pick it up with my hand. I could also pick up the whole desk. There’s ways for us to do this. There are ways for me to measure why I appear slightly blue if you’re watching this on YouTube and that’s called a photo multiplier of some sort that’s detecting the light flux. I don’t have one of those or my lighting might not suck quite so badly.
There are methods for us to do things, to measure things, to determine things. There’s technology that is defined through the physics that governs our universe. Occasionally physics comes along and says, no, you’re not allowed to understand that. You just can’t get data on that thing. There is no information. And when it comes to anything before moment zero of our universe, the arrow of time that we’re dealing with according to most general ideas of how our universe functions, the time originates right then and there.
Now there are a few theories out there that say that’s not when time actually originates and they can work to explain this in different ways. [Inaudible] [00:14:06] work on this problem. But even if we solve the arrow of time issue and time originating at zero of the universe, we still don’t have a mechanism according to modern physics to make any measurements of that time.
Fraser Cain: And so then all you’re doing is philosophizing and having an opinion, right. Like when you have this argument with people, all they’re doing is having an opinion, right.
Pamela Gay: Yeah.
Fraser Cain: Like I like chocolate ice cream best, right.
Pamela Gay: Yeah.
Fraser Cain: My feeling is that I’m gonna live forever and I can eat as much chocolate ice cream as I want. But just because you feel a certain way doesn’t mean the truth is different. So – and even if you do figure out a way to go before time and they go, oh, it turns out time did exist before the universe and the universe is just a bubble in a multi verse, what came before that? At a certain point –
Pamela Gay: Can’t get there from here.
Fraser Cain: Can’t get there from here, right, and so at a certain point you have to come to grips that there are questions that there will never be answers to.
Pamela Gay: What’s inside of an [inaudible] the ones that bothers people significantly. And it’s not even answering any fundamental questions about life. Like what came before the universe is kind of a fundamental, philosophical and religious question but what’s inside of a black hole is just annoying to not know. But there are people who are deeply, deeply annoyed not to understand what’s inside of an event horizon.
Fraser Cain: Some of them might be in this room itself.
Pamela Gay: Yes. But it’s simply a matter that because nothing can go faster than the speed of light, another thing method not found. There is no method to go faster than the speed of light. We can’t send a probe in and have it bring data back out. In fact, we can’t even look for stuff to come out of the black hole in a meaningful way that we can observe information from. So, again, method not found. We can’t look inside of an event horizon.
Fraser Cain: Maybe, right, because, I mean – well, no, I mean, I know you’re Miss Grumbly Pants but in theory with gravitational waves, we should – you know, with super accurate gravitational wave detectors we should be able to see the signal of two emerging black holes for example and try and get a sense, did they merge together really quickly, did they merge together really slowly? Did they bounce around somehow inside? Was there some kind of wobble inside the event horizon? Like there might maybe be an answer to the question as opposed to some of the other stuff that we’ve talked about, right.
Pamela Gay: So gravitational waves have the potential to give us some information about the time scales of mergers and other high density collisional events that are warping space and time. But that still doesn’t tell us what’s inside of a black hole.
Fraser Cain: No, but it gives us another method to maybe probe. That helps just a little bit. And same thing with the – you talked about this a bit already which is this idea of sort of the moment where you can’t see back to the big bang. But there’s a portion that will always be outside of our reach.
Pamela Gay: And, you know, one of the things I need to corner some cosmologists on is I’ve seen some news stories where people are talking about gravitational waves allow us to see prior to the cosmic microwave background radiation. But what gravitational waves let us see are when high mass objects interact with one another. But there weren’t high mass objects in any theory we’ve got. So there’s, as near as I can tell, no reason to believe there would be gravitational waves emanating from the cosmic microwave background.
Fraser Cain: But like with the primordial gravitational waves that they thought they had seen, this was sort of one of those possible signatures, and maybe there’s another way to get at those primordial gravitational waves.
Pamela Gay: And I – we’ll have to see.
Fraser Cain: Yeah.
Pamela Gay: Yeah, I’m a grumbly pants on this.
Fraser Cain: Yeah, you totally are, but that’s okay. So I think one thing that’s kind of interesting as well is that there, sort of hilariously – well, okay, so hold on. There are questions that we can know the answer to today that are – that people in the far, far future won’t know, right –
Pamela Gay: Yes.
Fraser Cain: — which is sort of like, you know, we ask is the universe finite or infinite.
Pamela Gay: Yes.
Fraser Cain: We can never know – we might never know because if all you can do is receive signals at the speed of light, how can you know what’s outside of the radius of the universe?
Pamela Gay: And if all the understanding in the universe that our civilization has and any other civilizations that are out there have, is lost then some day in the far distance future when all of the [inaudible] [00:19:37] are just islands that have nothing else within their Hubble horizon, then those peoples will have no ability to get at the idea of inflation or large scale structure any of these other things that we can observe today that will go beyond the observable horizon of those peoples of the future.
Fraser Cain: Yeah, so someone a trillion years from now won’t know that there was ever other galaxies.
Pamela Gay: Right. Well, they’ll know there were other galaxies. They won’t understand that there was other galaxy clusters.
Fraser Cain: Or that there was a big bang.
Pamela Gay: Exactly.
Fraser Cain: Which is crazy, right, that we happen to live at a time where this is a question that we could have answered but yet in the future. And, I mean, I guess if we happen to live 200,000 years after the big bang happened, we could answer that question too except we couldn’t see anywhere because everything would be opaque and we would also be on fire. But –
Pamela Gay: — and made of just hydrogen helium and trace amounts of other stuff but, yeah.
Fraser Cain: Yeah, then we wouldn’t be able to know. What are some other places where we can’t know?
Pamela Gay: So those are the big ones. The other things that we struggle with is how do you detect theorized particles like the graviton? We have no way of detecting it simply because it just defies all of our abilities to detect, which is highly annoying. So it’s this massless thing that travels at the speed of light and doesn’t interact in any ways that we have a method to discover.
So is there a graviton? Don’t know, and may never know. That’s another one of those things that’s just kind of annoying. There’s also the question that you’d think would have an answer but it leaves physicists getting shouty with one another of, does gravity philosophically bend space time in a way that manifests itself in all of the ways that we think of as bending space time. Or is that just a construct that we’ve come up with in our heads but the actual universe is just plain old [inaudible] [00:22:01] space with none of these deformations. It’s just how the particles fly.
And so there’s that philosophical, is space actually bent or is space not actually bent but this is a good mathematical construct? I don’t know if we can answer that one either.
Fraser Cain: Does time go in the direction that we think it does, right, or does the whole thing run backwards? Because mathematically if you do the time and the parody and the charge, you can run the whole universe backwards.
Pamela Gay: Well, so there I think it starts to get into simply word choice, forwards backwards, that’s a word choice. But there are other things that start to get into the same idea as the uncertainty principles. So for instance, it’s generally thought – and there’s a few experiments that people are arguing over the interpretation of, but it’s generally thought that you can’t see a piece of light a particle or photon of light as both a wave and a particle simultaneously.
So it may be that we have to treat things consistently as waves or as particles but only by doing things that may actually just be essentially physical magic that’s explainable. You can’t actually simultaneously see the wave and particle behavior.
Fraser Cain: And tides go in, tides go out. You can’t explain that.
Pamela Gay: I can explain it badly just like everybody else.
Fraser Cain: Yeah, that was a joke. So then one I think that really intrigues people, and we did a whole show on this, I mean, we’re intrigued too, which is this idea of the multiverse, right, that every moment we make a choice, every time a particle, a probability event happens, it could be generating entirely new multiple universes which the math works but we could never access those other universes.
Pamela Gay: There’s nothing stopping there from being an infinity of other universes out there. And we just can’t get there from here. So I just wanna bring up, there’s the movies Dr. Strange Love that has the fabulous title of How I Learned to Stop Worrying And Love the Bomb And I’m not gonna love the bomb but it might be that it’s okay to say how I learned to stop worrying and love what I can’t know. And it’s all right for there to be things that we just can’t know.
It’s, I think, more pleasing in some ways to have a universe that isn’t just so but instead has certain things that are just sort of, this is the thing that you can’t know yet or ever. And take that, humans, now you get to be perplexed forever. That’s kinda cool to me.
Fraser Cain: Yeah well, this is where, I think, you become our counselor, right, which is that I think for a lot of people, and I’m gonna definitely put myself in that camp, I’m comfortable to say I don’t know but I’m super not comfortable with saying, I can’t ever know. That my hope and faith is that these questions are just a matter of not having enough computational energy, not having enough time spent on the problem, not enough Einsteins being born and figuring this stuff out.
But I know in my heart that that’s wrong, that there are gonna be stuff that you have to just say, huh, that’s a mystery, and we’ll never know the answer to it.
Pamela Gay: And I think this comes with the difference of being able to accept wonder or not. Today’s apparently the day of quotes. I brought this up last week and then I went off and actually found it. There’s a quote by Thornton Wilder in the play Our Town and it has Emily, the lead character saying, “Oh earth, you’re too wonderful for anybody to realize you. Do any human beings ever realize life while they live it every, every minute?” And the stage manager responds, “No. Well, the saints and poets, maybe they do some.”
And this idea that we can’t fully understand how wonderful our universe is just with math and science and physics and thinking, that there’s some things that you just have to wonder at. And that’s where the poetry sometimes has to capture the things that the math can’t.
Fraser Cain: Right. But by your definition, that stuff doesn’t capture it either. It just makes the not knowing feel a little more palatable, you know. You’re still swallowing the same bitter pill but now you’re experiencing a little tingly, wonder and joy as you consider the bleak possibility is gonna be stuff that we can never know the answer to.
Pamela Gay: And I think it’s okay to sometimes have universe light as watered down and poets trying to express things that math science can’t because our meager little human brains just can’t fully comprehend that it’s okay to not know.
Fraser Cain: Yeah, and I love to have this conversation with people and where I’ll say like, well, where do you think the whatever, right, where do you think the universe came from? Like, I don’t know and I’m cool with that. And if you think you do know, you’re wrong. So you don’t know just like I don’t know and I’m okay with it and you’re not.
So that’s my – but I do like to have that argument with people, right, which is just like, you know, they don’t know. And I don’t know and nobody knows and that’s okay. You don’t have to know. So here we are at the end of Astronomy Cast knowing so little.
Pamela Gay: And that’s okay.
Fraser Cain: Yep. All right. Thanks, Pamela.
Pamela Gay: Thank you, Fraser.
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