Do Black Holes Create New Universes?

Thanks to bright.org for supporting PBS. What would happen if every

black

hole that formed in our universe caused the big bang of a new universe? Cosmological natural selection proposes exactly this, but even better: it claims to be able to test the hypothesis. Physicists have been struggling for some time to discover why our universe is so comfortable. Why, for example, are fundamental constants, such as electron mass or force strength, appropriate for the emergence of life? If we modify them too much, life, stars, galaxies and the universe as we know it would not exist. In recent episodes we explored a possible explanation for this: the anthropic principle and the idea of ​​the multiverse.

If there are countless

universes

with different fundamental constants, then it's not surprising that a few exist with the right numbers for life, and it's certainly not surprising that we find ourselves in one of those good ones. But if you don't like the anthropic principle (and many scientists don't), rest assured, there is an alternative. We only have to accept two things: that our universe formed inside a

black

hole and that

universes

can evolve. Our universe seems, in a sense, designed. It has finely tuned parameters that seem deliberately set for a particular outcome: life. There is another example in nature where the illusion of design has a perfectly natural explanation: and that is life itself.

We now know that the fantastic complexity of living organisms is an inevitable consequence of evolution by natural selection. Inspired by biological evolution, theoretical physicist Lee Smolin devised Cosmological Natural Selection. He goes like this: the formation of a black hole triggers the formation of a new universe "on the other side" in a new big bang. These daughter universes continue to expand and

create

their own black

holes

and, therefore, their own daughter universes. But in their formation, the fundamental constants of the daughter universes shift slightly and randomly from their parents: mutations are introduced. Some of those changes improve the daughter universe's ability to form new black

holes

.

Those universes have an advantage in propagating their cosmic genetics, so gradually the aggregate of all universes gets better and better at creating black holes, just as biological organisms with useful mutations can get better at surviving and reproduction. Now, by happy chance, there is a correlation between the creation of many black holes and the creation of life; both require stars. The universe that is best at forming stars is best at creating planetary systems and is best at creating us. Seems fair enough. But is it more than just an interesting story? Brother? Let's analyze this to ask two questions: is it plausible and testable?

First of all, for all of this to make sense, black holes need to

create

universes. This is by far the most speculative part. In fact, we have no idea, and only very tentative reasons to think so. The idea came from one of Lee Smolin's mentors, Bryce deWitt, who postulated that when a black hole collapses, not all of its mass ends up trapped in the central, infinitely dense singularity. Rather, it bounces off, but unable to leave the black hole's event horizon, it forms a new region of space-time, effectively creating a new universe. The details of how this happens are presumably buried in the still unknown theory of quantum gravity.

There are several proposals for how this rebound could occur; These are all hugely speculative and we may discuss them another time. John Archibald Wheeler expanded on the idea of ​​black hole procreation by suggesting that the fundamental constants of these new universes could be different from those of his parents. This seems plausible: if the fundamental constants can change, then it will surely be in environments with the highest possible energy, which is exactly the end of a black hole collapse. Perhaps the configuration of the additional dimensions of geometric string theory will be changed; this would work. Inspired by this idea, Smolin added one thing: what if, when universes reproduce, the constants are not randomly reconfigured but change only slightly, analogous to a small number of genetic mutations?

If that were the case, a kind of evolution by natural selection would be as inevitable as biological evolution. We have no good reason to believe in this whole procreative universe thing, and Lee Smolin has readily admitted as much. Instead, the question is to ask: what if it is true? What are the consequences? And can we try them? The exponential nature of the proposed process means that the set of all universes should very quickly be dominated by those that are extremely good and produce black holes. Any given universe may not be fully optimal because its constants vary randomly from its parent, in the same way that any living organism is not the model of its type.

So there is a prediction: the fundamental constants that define black hole production should be close to optimal in a given universe, at least for a given mechanism for producing black holes. In our modern universe, black holes form when the most massive stars explode as supernovae. There are other ways to create black holes and we will return to them. Therefore, we should expect our universe to be optimized to produce as many more massive stars as possible. Well, is it? It's actually very hard to say, but it looks like there are some adjustments there. Stars form when giant clouds of gas collapse under their own gravity.

But for that to happen, the gas needs to be cooled to just a few degrees above absolute zero, rather than the typical 200 Kelvin temperature of the typical interstellar nebula. This cooling is extremely slow if the gas only contains the hydrogen and helium produced in the big bang. Heavier elements and molecules allow clouds to cool and stars to form much more quickly, and of these, carbon monoxide is by far the most important coolant. Additionally, the gas needs to be protected from the heating effect of other stars, and that appears to require the presence of small particles of ice and hydrocarbon dust.

Thus, without carbon, oxygen, water and chemistry in general, many fewer stars and fewer black holes would form and, of course, these factors also seem to be essential for life. But what about other sources of black holes? Theoretical physicist and cosmologist Alexander Vilenkin proposed that if a universe lasts forever, in the distant future, quantum fluctuations in that near vacuum will cause the spontaneous appearance of black holes, and given infinite time, these will eventually outnumber those produced. by stars or stellar black holes. If all of this is true, then most black holes would be produced by larger universes: more space means more chances for these quantum fluctuations to occur.

This encourages a lot of dark energy to generate rapid expansion. And that is definitely not our universe. Lee Smolin has several arguments against this: for example, we don't know if our physics can really be extrapolated to the incredibly long time scales needed for these quantum fluctuations to occur. He would also add that even if Vilenkin's argument were valid, there is no doubt that there are different regions in the landscape of possible fundamental constants where different types of black holes are optimized. This would lead to multiple branches of the cosmic gene tree, some of which correspond to the production of many stellar black holes.

And naturally we would find ourselves in one of those branches because it turns out that those are also the ones that favor life. But wow, I just invoked the anthropic principle, which is exactly what we're trying to avoid with this whole idea. As speculative as all this is, Smolin says there is concrete proof for the idea. If cosmological natural selection is true, then the fundamental parameters that favor the production of black holes should be optimized completely independently of those that also favor the emergence of life. And he suggests that there is one such parameter. But first some background.

When massive stars die, they actually produce mostly neutron stars: planet-sized balls of neutrons so dense that they are on the verge of collapsing into a black hole. Black holes only form when neutron stars exceed a certain mass limit. Now, it may be that in the cores of the most massive neutron stars, some particles can become strange quarks. The resulting material is even denser than the original neutron star, so the star is closer to collapse. And the lower the mass of the strange quark, the easier it is to convert lighter particles into strange quarks. This, in turn, means that less massive neutron stars could collapse into black holes.

So, surely, if universes evolve to maximize the number of black holes, then the strange mass of quarks should be optimized to make the boundary between neutron stars and black holes as low as possible. Lee Smolin calculates that optimized limit to be about 2 times the mass of the Sun. So if this universe is optimized for black hole production, then there should be no neutron stars with more mass than 2 solar masses. AND? Well, the most massive neutron star known is 2.17 solar masses and was discovered this year. Now perhaps the extra .17 can be included in the uncertainties of the theory...

Or perhaps this is the fake we were looking for. We await Smolin's comments on this matter. I would like to add my own objection: cosmological natural selection purports to explain the fine-tuning of fundamental constants, which appear to be determined by design or extreme luck. It attempts to avoid the anthropic principle by proposing natural selection that favors the production of black holes, and it is simply a happy coincidence that the same factors also favor life. But then do we really gain something? It just so happens that carbon and oxygen are good for both black hole production and organic molecules... but what if it was, I don't know, beryllium and boron that helped form stars, or other elements that were useless for life?

If we causally disconnect the selection process for cosmic reproduction from the emergence of life, it seems like we still have to invoke a lot of good luck? Overall, cosmological natural selection is an attractive idea because it seeks a natural explanation for fine-tuning, and an explanation that parallels a known process in nature: biological evolution by natural selection. It also seems to give us predictions that we can try to prove and disprove. And although this idea is probably not true, it is very important to remember that speculative ideas like this are exactly how we explore the limits of science.

None of them are likely true, but they help us explore the vast space of all possible realities, where somewhere the true nature of our reality is hidden. Or, you know, the mother of our universe could be a black hole, and we live in a constantly evolving and proliferating space-time. Thanks to bright.org for supporting PBS. If you want to understand astrophysics, you will need to have a solid knowledge of relativity. Brillaint.org has a special relativity course that includes interactive challenges and problems to solve. A hands-on approach can guide you through thinking strategies for challenging topics like relativity.

In this course you will begin by understanding Einstein's postulates and Lorentz transformations and, as your knowledge advances, you will learn how traveling faster than light can break causality and even solve the famous twin paradox. For more information about Brilliant, visit shiny.org/Spacetime. Hello everyone, thanks for watching. Your support each week is what makes this program possible. Now, it's totally optional, but one way to help even more is to become a Patreon supporter. Even with $2 a month you can access our Hopping Discord channel. Thank you so much if you've already joined us, and today a huge special thanks to Big Bang supporter Craig Stonaha.

Craig, as a small token of our gratitude, we've reached out to our friends at the Large Hadron Collider - they're going to turn you into a universe of black holes. Send us an email with your preferred fundamental constant settings and we will send it directly to you. Oddly enough, it's the same shipping company as our merchandise store, which you can check out at pbsspacetime.com. Last week we talked about the doomsday argument: the disturbing idea that, statistically speaking, there are not likely to be many more generations of more humans than in the past. There were a lot of counterarguments, maybe good ones, because apparently we're still here.Many people raise a similar objection.

I'll quote Mr. Fantastic, who put it well: a human born 2 million years ago would conclude that the end of the world is near, and so would a human born 2 million years from now. If we accept the reasoning of the apocalyptic argument, doesn't this simply mean that we would all, throughout history, come to the conclusion that we are all going to die sooner rather than later? This point is totally valid; in fact, a Cro-Magnon would have to come to the same conclusion and predict doom long before the 21st century, and they would obviously be wrong. But the apocalyptic argument does not say that all members of a species who use this reasoning to predict the fate of their species will be right.

He says that most will be right if they predict that there will be a similar number of future generations as there are past generations. And by similar I mean a factor of a few. So the ancient philosophers would have been wrong, and perhaps eventually we too will be wrong ancient philosophers to some very distant future generation. The thing is, if a given individual assumes that we are a random sample of all the generations that thought up the end-of-the-world argument, then he is probably nowhere near the beginning of his species. Now, the real problem with the end-of-the-world argument is not that its users in the distant past were wrong.

Rather, it is not at all clear that it is reasonable to consider ourselves "randomly selected" from all users of the doomsday argument. Zahaqiel highlights this complexity in defining the reference class with a great example: Step 1: He defines the reference class as "homo sapiens sapiens existing simultaneously with the Internet." Step 2: Note that the Internet has been around for about 30 years. Step 3: Suppose the self-sampling assumption makes sense and that Internet access has a curvature throughout its existence or is biased toward late-stage access... Then the Internet will cease to exist at some point in the next 30 years, boys. No one highlights another misuse of this idea.

To quote: "What are the chances that I will be born a prince of France?" asked the prince of France. Well, from the Prince of France's perspective, the answer to that question is a probability of 1. From everyone else's perspective, the answer is a probability of 0. And this really highlights the challenge of identifying our "reference class." " for this type of anthropic reasoning. Now, the Prince of France knows that he is the Prince of France, so from his perspective, the probability that he is the Prince of France is 1. But imagine that the Prince of France was raised in secret in a normal French family.

He doesn't know who he is; all he knows is that someone among the population is the Prince of France. If you ask him the probability of him being Prince of France, you should probably say 1 in 33 million, or whatever the male population of France is. The point is that you must take prior knowledge into account when defining your reference class. Nick Bostrom has another good example of the misuse of the apocalyptic argument. Adam and Eve really want to... you know, hook up. Except they are afraid of God's wrath if Eve gets pregnant. The serpent arrives and explains that, according to the end-of-the-world plot, Eve's chances of getting pregnant are almost zero.

After all, it is incredibly unlikely that Adam and Eve will be the first two among billions or trillions of future humans; Therefore, chances are they can have all the fun they want without the risk of spawning an entire species. But even better apocalyptic nonsense came from thatisjustgreat, who says: "It was 30 seconds in when I realized the video was probably almost over." By that logic, this video is only halfway done.