Black Holes, Gravity Theories & the Quest for Planet Nine

theory Hubble tension. Not surprisingly, questions about planet nine with the most recent announcement of something being out there that's not planet nine. And, um, getting gravity assistance to Max Delta V. Those are all the questions coming up on this episode of space nuts.

Unless it's a super interesting person like yourself. Right. Professor Fred Watson: No, I'm, I'm capable of boring the pants off people as, uh, people have assured me before. So that's all right. So we've got a lot to get through and uh, it's, it's even trickier this week because we do have a technical, uh, issue, which means you are going to have to lip ring. Professor Fred Watson: Okay. Uh, so. Right. I'll do my best. We'll see how that.

Professor Fred Watson: I'm wondering where the lips are going to be. That's the only thing. Yes, yes. Well, the first set of lips come from Paul. Uh, so let's hear his question.

And another fellow chipped in, Nikodem Poplowski from New Haven, suggested that maybe that was because our universe was born inside a black hole. If that is true, how the heck did we get out? And if we didn't get out and we're still inside, then how is that possible given that, you know, anything that goes inside a black hole, uh, is spaghettified according to our current thinking and therefore incoherent. I mean I know

I'm incoherent, but you know what I'm talking about. Talking about when it comes to ordinary baryonic matter. Uh, love to get your thoughts on this. Anyway, uh, keep up the good work and catch us later. Cheers.

I've got a bit of an idea of what Paul was suggesting. The fact that um, we have uh, new observations which uh, have been made with the James Webb Space Telescope, uh, that um, are intriguing in the sense that uh, these scientists, uh, and they are basically uh, mostly located at Kansas State University. Uh, the, the rotation of galaxies in the deep universe isn't random. Uh, you'd expect, you know, galaxies to be rotating in.

They can only go one way or the other. But you would expect an equal balance of rotations. Uh, and uh, what find, uh, or what these scientists find at Kansas State University using the James Webb Space Telescope Advanced Deep Extra galactic survey or jades, um, what they find is out of 263 galaxies, um, which you know, which give away their rotation because we know that spiral arms nearly always trail. There's at least one galaxy where the spiral arms are leading

but most of them trail. And what they find is that out of these 263 galaxies, about two thirds of them are going clockwise and the rest are going anticlockwise. And that is an imbalance. That's a statistically significant imbalance, uh, that suggests that something's going on that we don't understand and that leads to the possibility that perhaps the universe itself

is rotating. Um, and I've seen other um, papers um, on this topic that suggest that maybe the universe rotates once in every 500 billion years. That's one figure that I've seen now, um, a consequence of the rotating universe. And I think this is where Paul's question went. I'm trying to remember having heard it yesterday, uh, is that it lend some weight to the idea that the universe is

inside a black hole. Uh, in other Words that there is an event horizon at some huge distance from where we are, uh, and we are all within this black hole. Um, what does that mean for observational cosmology? I suspect it's going to be very difficult for us to confirm that ever. Uh, and I think, um, you know, this is speculative research. It's important research because you, you, you want to know

um, how some of these things interact. And I might just mention, and I think we've discussed this before, Andrew, on space nuts, that the idea of a rotating universe actually relieves some of the issues, uh, that we find uh, in observing the universe. One of them is the Hubble tension. And I know there's a question coming

up about that. Um, so a rotating universe has certainly attractive possibilities, but we absolutely don't know whether it is a rotating universe and indeed whether that means that we're inside a black hole. Uh, so what I was going to say was the idea of a universe within a black hole is akin to the idea of multiverses. The idea that um, um, multiple universes exist and we are just one of them. I'm not really, I don't think giving a sensible answer to Paul's question,

partly because I couldn't hear it. But I think he was basically asking, you know, what happens? How does it happen? Uh, how are we not being spaghettified? That's because, uh, I can tell you the answer to that. Uh, we're not in a region, um, of the black hole where the um, gravitational pull is changing very, very rapidly with space. And that's what makes a black hole spaghettify. You, you go from one point to another and your gravitational pull is very different.

So your head feels a different gravity from your feet and you get spaghettified. We're not in a place where that would be happening if we were inside a black hole. But uh, you know, all bets are off because inside a black hole, uh, there might. We're in a different dimensional space. A black hole is a singularity. Are, ah, we in a singularity? A singularity is a point with no dimensions. Work that one out. So we'd have to be almost in a different

dimensional space. So it's an interesting question, um, to which I don't think anybody knows the answer, but there are a few people who are probably thinking through it a lot more clearly than I am. Well, Paul mentioned uh, a physicist by the name of Nicodem, um, Poplaus, uh, he's one that's put this theory forward that um, our observable universe is not just a part of a larger universe, but is in fact the interior of a black hole within a larger context.

Professor Fred Watson: Yes. So you've got extra dimensions somewhere out there within, uh, which we exist. Uh, that's right. It's, um, uh, you know, I, I, Yes, I remember, um, checking out the, the researchers that, uh, that Paul mentioned yesterday when I looked at it. Uh, it's interesting stuff. Yeah. What do you think, personally? I mean, is there any possibility that this could be real? Professor Fred Watson: Um, to me it's on the same level

as does heaven exist? Uh, you know, it's questions to which we really can't find answers. We can theorise, we can conjecture, we can speculate, we can write equations down. And probably some of the equations do support the idea that we're within an event horizon. It goes back a very long way. It's not a new idea at all. Um, but, um, I mean, people have put new numbers on it, I think, and, um, new observations. I think

we, we watch this space. Next time this question comes up, I might be able to hear it properly and might be able to give a more cogent answer. Yes, indeed. I'll be working on that technicality. Professor Fred Watson: I don't, I'm sure it's not your fault, Andrew. I know what these gremlins are like. We get them all the time. Yeah, I'll blame the equipment. Never ever, though. Professor Fred Watson: Never the place. New Z. No, that's true.

Thank you, Paul. Hope we covered that adequately, as we strive to do here on Space Nuts. Professor Fred Watson: Space Nuts. Uh, our next question, Fred Watson, comes from Casey in Colorado. In fact, he has two. Could you please explain the new theory of gravity in simple terms? Does it, uh, have any merit? And could you, uh, please explain hubble tension and what it means for our understanding of the universe? Professor Fred Watson: Yes. Uh, so that's the answer. The answer is yes. Yes, I can.

The new theory of gravity, which I like very much. Um, this comes from scientists in Finland, which is a place that I like very much as well. Um, and it's what they've done, you know, they've taken, um, a step forward. And I'm assuming this is the, uh, this is indeed the, um, the, uh, the, the new theory that case is speaking about, because we get nearly one every week, a new theory of

gravity. But this is the latest one. Um, it's, uh, as I said, it's from, uh, it's from, uh, Finnish scientists, uh, at Aalto, uh, University. Um, so it's what they've done is what Einstein tried to do for the last, for 30 years of his life. Uh, which is to unify quantum field theory and relativity. And uh, that's an issue because uh, they are incompatible at ah, the levels that we try and look at them now. Um, and so uh, to bring a quantum theory of gravity into being

is a big step. So um, what do I mean by, by bringing a theory into being? Well we know that there are four fundamental forces in nature. Uh, the strong and weak nuclear forces, electromagnetism and gravity. And the first three of those have very, very well established and well uh, understood quantum theories. Um, for example, we know that electromagnetism is propagated by photons. We're talking about it all the time. So the suspicion is that gravity uh, is propagated by

gravitons. But so far there's been no theory of what gravitons might be like. So what these scientists have done have developed a new theory, uh, a new quantum theory of gravity. Uh, and I'm actually going to once again ah, quote from phys.org, very uh, nice account of this, um, uh, which is actually, I think it is part of the press release from Aalto University in Finland. So I'm quoting

the university. Um, researchers at Aalto University have developed a new theory, quantum theory of gravity, which describes gravity in a way that is compatible with the standard model of particle physics, opening the door to an improved understanding of how the universe began. While the world of uh, quant theoretical physics may seem remote from applicable tech, the findings are remarkable. Modern

technology is built on such fundamental advances. For example the GPS in your smartphone works thanks to Einstein's theory of gravity. Uh, and then uh, the article goes on to describe the theory is published in uh, Research Reports on Progress in Physics. Um, and this is the quote that I wanted to make. This comes from the lead uh, author of the paper. Uh, and um, um, basically they um, they've got lovely Finnish names. That's why I'm stumbling. It's Mikko Partanen, uh, who's the um,

lead author. Uh, and the quote is as follows. And this kind of puts it into perspective, if that's the big word. If this turns out to lead to a complete quantum field theory of gravity, then eventually it will give answers to the very difficult problems of understanding singularities in black hole and black holes and the Big Bang. A theory uh, that coherently describes all fundamental forces of nature is often called the Theory of Everything. Uh, some fundamental questions of physics still

remain unanswered. For example, the present theories do not yet explain why there is more matter than antimatter in the observable universe. Uh, and what they've done is, um, they've developed something called a gauge theory. And gauge theories are a particular kind of theory about the way particles interact with each other through a field. Ah, like the Higgs field and the Higgs boson. Um, so, uh, it's basically a

very nice a, ah, very nice account. I won't read any more because, you know, gauge theories got symmetries and things of that sort. Um, it's, um, a nice account. I recommend people have a look@the phys.org uh, paper. Uh, uh, sorry, the

fizz.org article. Casey, I'd send you to that as well to have a look. It's a very nice account of, of what's happening. You may end up like me thinking I really need to know a bit more about gauge theory before I can understand this. Uh, but, uh, nevertheless, you'll get, um, a good idea of what's going on, I think. M. Okay. Now, Casey also wanted you to explain, if you could, Hubble tension. Professor Fred Watson: Yeah, that's an easier one. And, uh, as we've spoken about.

That's good. Professor Fred Watson: As we've spoken about today, uh, that's one of the things we might get rid of. Yes, Hubble tension is a lot easier than gauge theory. Um, and what it amounts to is we've got two ways of calculating the current expansion of the universe. Uh, one is by looking at galaxies in our vicinity, uh, and looking at the rate at which they are speeding away from us. They're moving away from us faster as their distance

increases. This is exactly the discovery that hubble made in 1929. And, uh, gives us something we call the Hubble constant, which is just the rate of expansion of the universe. Today we call it, ah, h. Naught, um, Hubble zero, which is the expansion rate today. Now, you can also get an idea of that or a measurement of it from the cosmic microwave background radiation. And that, to recap, is the flash of the Big Bang. We're looking back so far

in time. We're seeing back to a time 380,000 years after the Big Bang, when the universe was still opaque and glowing brightly. So we see this wall of radiation which is now in the microwave region of the spectrum, uh, and it's peppered with a pattern of warmer and cooler places, uh, and those, uh, zones of higher and lower temperature, and it's only by a tiny fraction, uh, they correspond to the

structure in that fireball. Um, in fact, it's caused by sound waves moving through it, they're called baryonic acoustic oscillations. And we can, by measuring the properties of that peppering of warmer and cooler regions, we can actually work out what the expansion of the universe is today. And it turns out that the two figures are different, um, by something like 4 or 5%. And that in modern terms is big enough to worry about. It's

not just an error of measurement. Uh, these have got fairly tight limits on the uncertainties, but they're different. And that is the Hubble tension. Hm. But didn't they recently, recently release a paper that suggested that the variations are actually within a normal range? That this, this, these two figures that don't match are, ah, close enough? Professor Fred Watson: Well, yes. Didn't we talk?

Professor Fred Watson: We did that. Um, some people have suggested that, that it is, that it is actually within the experimental uncertainty, but it's still seen as attention. They could, they should be nearer than what they are. Yeah, okay. Very, very interesting, Casey. Thanks for both your questions. And no, you haven't spammed us. Two questions doesn't equal spam. There's probably a definition somewhere online that says how many, how many emails become spam.

You're well, well outside that tolerance. So no problem there. Uh, this is Space Nuts Q A edition with Andrew Dunkley and Professor Fred Watson Watson. Space Nuts. Okay, Fred Watson, let's uh, move on to our next question. It's an audio question so you won't be able to hear it, but it comes from Simon.

Simon asked. And what he's saying is that we know that when we look for exoplanets, planets around, uh, other stars. What we look for is the change in position of the star itself as it's pulled one way and another by the planet orbiting around it. And yes, indeed, the solar system, uh, has such an effect. So Jupiter principally is the main planet that's pulling the sun's centre one way or the other. Uh, but the other planets all

intervene as well. And so what we have is something that's called the solar system's barycenter, the centre of mass of the solar system and that moves as the planets wander around. And, um, we've exactly as, um, Simon says, we've managed to work out the position of the barycenter very, very accurately, uh, partly because we know where the planets are and things of that sort of. Now, Simon's question is actually exactly the same as a question that I found on Stack Exchange Online.

The question was, wow, can the paper narrowing the solar system's barycenter to within 100 metres help find Planet Nine? Uh, so that's basically what Simon asked. And the bottom line, there's a long, long set of calculations here which I won't go through, but the answer is probably not. Um, uh, it's because the Planet nine's influence on the solar system's barycenter, it's helped by the fact that Planet nine's a long way away. Um, um, so it's got sort of leverage, uh, as it goes around.

Um, um, the short answer is maybe we could do it, but we wouldn't be able to do it without hundreds, if not thousands of years of precise data. And that's because Planet nine is probably orbiting the sun on that kind of timescale. And so you don't see any, you know, what you'd be looking for is, um, changes in the position of the barycenter, which are not caused by the

known planets. But it'll take you hundreds or thousands of years to see that because of the great distance that Planet nine is at. So the answer is probably not, but it's a great question and really nice thinking. I like Simon's thinking there. Yeah, yeah, it's quite astute. Uh, the other factor that comes into play here is the new theory that Planet nine doesn't exist because there's another planet even further out that, uh, has only just been sort of put into, um, a

pager and open for discussion. So we only talked about that last week. So the search for Planet nine might be a forlorn hope anyway, uh, um, because it probably, according to the new theory that's correct. Professor Fred Watson: Yeah. Now, the new theory is based more on observations than theory because it's two observations separated by something like 30 years that seem to show something moving very slowly in the outer solar system. You can bet your life will do more observing of that over, uh,

uh, coming decades. Uh, and maybe that will turn out to be what I think is being called Planet eight and a half at the moment, because nobody really knows whether it's there or not. But as you said, if that is real, it rules out Planet nine. The two can't exist together. Exactly right. All right, there you go, Simon. Um, we'll see where that, uh, ends up, but it might take a while. Uh, final question comes from Joe in Olala in Washington. I hope I pronounced that

correctly. Is there an upper limit to how much Delta V, uh, that can be practically generated by gravitational assists? Is it possible to develop sufficient Delta V for timely interstellar travel by winding up a probe in our solar system before launching it, uh, to a nearby star? Uh, thanks for all that you do. Cheers, Joe. Now, Delta V, that is the impulse per unit of spacecraft mass, yes? Professor Fred Watson: Well, it's basically the change in velocity.

Um, yes. And impulse is the, uh, that's the way people talk about these Delta V's in this, in the rocket industry. It's all rocket science. What is it anyway, Delta V, uh, I think in Joe's context here is how much velocity increase you can get from a gravity assist, from a, ah, slingshot.

Uh, and the answer is probably no, um, in terms of trying to wind up, you know, the speed of things so that you, you know, you tell something out of the solar system at 10th, uh, the speed of light or something like that. Um, the reading that I've done on this, and I did check it out seems, uh, to suggest, excuse me, that um, we are probably limited to, um, the sorts of velocities that we see among the planets of the solar

system. Now remember, the Earth is orbiting the sun at 30 kilometres per second. Um, and, um, those velocities get less as you get farther away from the sun. And that's part of the equation with a slingsot, because what you're trying to do is steal some momentum from the planet and,

and give it to the spacecraft. And so there are upper limits, uh, on, um, what sort of velocity change you can get. It depends on how close you go to the planet, depends whether the planet's got an atmosphere or not. It, uh, depends on the angle that you come in. Um, the figure that I've seen quoted As a maximum for Jupiter, which is the most effective planet for this sort of thing, being by far the most massive planet in the solar system, is a change of 40 kilometres per second.

Um, now that's very good if you're you know, trying to get something out to the outer solar system, but it's not going to help you getting things to other planets. Especially when you think, you know, if you give uh, a planet, sorry a spacecraft, an impulse Delta V of 40 kilometres per second by interacting with Jupiter, you've got to then find another planet that's, that's going to give it even more. But the other planets are all moving slower than that so uh, the change in

momentum is a lot harder to get. Uh, so I think the answer is it's a very nice idea. As Joe suggests, winding up by all these gravitational interactions, you can only do it within limits. You're not going to be able to get like 100,000 kilometres per second or something like that from doing that. Yeah, I suppose you could equate it to using a slingshot or a shanghai. There's only so much tension you can push, put in, into the, the rubber band,

let's say to fire the rock. And you're not going to be able to fire the rock any faster than the maximum amount of storage the rubber band can hold. And I'm guessing it's the same. Professor Fred Watson: Yes, there's a, there's a limited amount of energy that you can get from, from a slingshot. That's right, yeah. Nice idea there. Although it's, it's been very effective as you said, for sending things to the outer solar system.

The, the Voyager probes particularly uh, used um, the slingshot effect, um, several times to get to the outer solar system because they didn't have the fuel to do it. So they figured out through um, an alignment of the planets that they could get out there just by using the rotation of the planets or um, the process uh, that uh, uh, Joe's been talking about. So um, yeah it does work quite effectively for slower, slower speeds that uh, yeah, interstellar, probably beyond us in that regard.

Professor Fred Watson: Yeah, probably the lasers and um, you know in a solar cell or a light sail might be a better bet. But even that beyond our technology at the moment. Um, probably won't be for long though. I think they'll develop that and get some spacecraft heading out towards the Alpha Centauri sector and um, anyway that remains to be seen. Uh, but that would still be a pretty slow mission in the scheme of things. But um, yeah, great question Joe,

thanks for sending it in. And if you'd like to send us a question, uh, you can do that, uh, through our website, spacenutspodcast.com spacenuts IO. Click on the AMA link at the top and you can send us text and audio questions. And don't forget to tell us who you are and where you're from. We love to know that sort of stuff so that we

can send the boys around. Or, uh, we could send Huw around because he can't be with us today, so he must be visiting one of you guys, um, with his, with his, um, you know, balaclava on, maybe. Yeah. Professor Fred Watson: Thank, um, you, Fred Watson, as always, a pleasure. Andrew, as always. Good to talk and uh, good to hear our listeners questions. It's. It is, it is. All right, well catch you again real soon. Professor Fred Watson Watson, astronomer at large, and from me,

Andrew Dunkley. Thanks for your company. See you on the next episode of Space Nuts. Bye for now. Professor Fred Watson: You've been listening to the Space Nuts. Podcast, available at Apple Podcasts, Spotify, iHeartRadio or your favourite podcast player. You can also stream on [email protected]. um, this has been another quality podcast production from Bytes. Professor Fred Watson: Com.