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Cosmological Musings

Entry 1887, on 2017-11-30 at 20:10:33 (Rating 2, Science)

Recently I have listened to a few podcasts featuring some of the most well known scientists of today. Specifically, I mean Lawrence Krauss, Sean Carroll, and Neil deGrasse Tyson. These aren't general scientists obviously, since they all specialise in physics and cosmology, but that's the area I want to concentrate on in this post.

I admire these three in particular for a number of reasons: first, they are clearly brilliant and highly intelligent people, or they wouldn't have got to the positions they have; second, they are good public communicators of the often difficult subjects they specialise in; and third, they aren't scared to call out BS where they see it, and Carroll and Krauss in particular are very critical of religion and other forms of irrationality.

But it isn't the politically or socially controversial topics I want to cover here, it is the scientifically contentious or speculative stuff instead. So let's get started talking about some of the more speculative ideas I have heard discussed recently. Note that these aren't necessarily directly attributable to the people I mentioned above, and they represent my interpretation of what I have heard, and I am not an expert in this subject. But that has never stopped me before, so let's go!

The origin, and underlying nature of the universe is not well understood. This has been a problem for a while, because the actual point where the Big Bang started is hidden in a singularity of infinite density. Physics breaks down there, just like it does in a black hole, so nothing much can be said about it with any certainty. It is possible to use existing theories to get really close to time zero - a tiny fraction of second - but beyond that is inaccessible to current theories.

And the best direct evidence we have comes from the light of early galaxies and the cosmic microwave background (CMB). But even the CMB only formed after 300,000 years, which is s small fraction of the age of the universe (13.7 billion years) but still not as early as we would like.

So clearly this is a difficult subject, but here are a few observations and speculations about the universe which might assist in understanding what is going on...

The first point is that the total energy of the universe might be zero. This seems totally absurd on the surface, because of all the obvious energy sources we see, like stars, and all the mass which we know is the equivalent of energy through the famous equation E=mc^2. But that's where a convention in physics makes the reality quite different from what most people intuitively believe.

Gravitational energy has always been thought of as negative. This is nothing to do with the Big Bang or cosmology, it is just a natural consequence of the maths. If we accept this it turns out that the gravitational energy of the universe cancels the other energy exactly. So the universe has zero energy which means that any process making a universe can do so easily, meaning there could quite conceivably be an infinite number of them.

While some people dismiss this as a "trick" it really isn't. If cosmologists had said something like "we need to get the total energy to zero so let's just say gravity is negative and voila!" then that would be a trick. But this was an established fact long before the total energy of the universe was being considered and this gives it far more credibility.

And while we thinking about the idea of more than one universe, what about the idea that there could be many universes - each with slightly different properties - which might explain why many of the properties of our universe seem to be quite well tuned for the existence of life?

What I am saying here is that various constants seem to have values which make chemistry possible and that, in turn, makes life possible. But there seems to be no reason why the constants could not have totally different values and this could lead to a universe where stars could not form, and no stars means no energy source for life.

And the old argument about life which is entirely different from the type we see now doesn't really save us because any form of life needs both energy and heavy atoms, and stars are the only likely source for these.

But if there are an infinite, or very large, number of universes, with different constants, then it is inevitable that some will have the values which make life possible. In fact, it's possible to imagine a universe which is even better than ours for life, so there could be many which have life. In fact, if there are an infinite number of universes, there will be an infinite number with life as well!

A concept I have sometimes heard in both pop science and science fiction is the idea that at very large scales and very small scales there might be other universes hidden. For example, an atom could be a universe made of its own tiny atoms which in turn could be universes, etc. And going the other way, our universe could be an atom in a bigger universe above ours, ad infinitum. This idea might arise from the popular notion that an atom is like a miniature solar system (which it isn't).

It's a cute idea, but unfortunately it can be ruled out by applying the laws of physics. Sub-atomic particles have no details and no uniqueness. For example, every electron is a single point (or "cloud" of probability) with no structure and which is completely indistinguishable from every other electron. This doesn't seem like a good candidate for a whole universe!

What about the "oscillating universe" or "big crunch" theory? This is the idea that the universe expands but the expansion slows down until it stops at a certain point, then it starts contracting again, reaches a singularity, and is "reborn" in a new Big Bang. At this point any vestige of the old universe is erased and all the energy is replenished. This would be a process which recurs infinitely in both the future and past.

This is quite an appealing notion, because it tells us what was before the current Big Bang, and previously it was thought that gravity might have been slowing the rate of expansion. Unfortunately for this theory new evidence shows us that the rate of expansion is actually increasing, because of dark energy, so the contraction and "Big Crunch" can never happen.

There's nothing fundamental in physics which seems to stop processes running backwards in time. I have heard an idea that maybe the universe was created as a result of a signal sent backward from a future form of the universe itself. This removes the need for an initial cause which in turn might need a cause, leading to an infinite regress of causes.

Signals going back in time should be considered somewhat controversial, of course, because of the principles of causality, so I would be hesitant to take this too seriously unless some clarification on the exact mechanism arose.

Here's another one: new universes appear inside black holes created in existing universes. These universes all have slightly different attributes than the universe they came from, but inherit the starting parameters from them.

This is nice because it sets up an "evolution" model where "the survival of the fittest" applies to whole universes! Only universes which can make black holes will create new universes. To create a black hole the universe needs to have a fairly long life, a way to concentrate matter, a way to allow matter to "condense" out of energy, etc. These attributes also lead to laws and constants suitable for the development of life.

Clearly this is difficult to evaluate because we don't know what happens inside black holes, because as I said above, the infinite density of matter causes current theories to break down. There is no compelling reason to think universes are formed from black holes so it's probably best to disregard this idea unless some new, relevant information becomes available.

Finally, how about the idea that the purpose of a universe is to allow intelligent life to form which, in turn advances to the point where it figures out how to make universes?

This also sets up a potential evolutionary scenario, but we have no idea whether any intelligent life form, no matter how advanced, could create a universe, so again this seems to be somewhat unworthy of spending too much time speculating about at this stage.

Well, wasn't that fun! Obviously we don't know the truth about the origin or fundamental nature of the universe, not because we have no ideas, but because we have too many! I'm fairly sure that when real theories are created to explain these phenomena that none of what I have said here will be the real explanation, but it's still fun to speculate!

Comment 1 (4852) by Anonymous on 2017-12-04 at 12:13:50:

Sounds like a lot of primitive myths just like what you say to creationists. I think our stories have a lot more evidence than yours. When will you be joining our church? You're welcome...

Comment 2 (4855) by OJB on 2017-12-06 at 23:00:03:

Well, I totally agree that some of what I said should not be taken seriously. That in itself is a major difference between my speculation and religious myths, which many people insist we should take seriously. Also, some of the ideas in this post are based on real science, and might eventually even be supported or disproved by observations or experiments.

Comment 3 (4857) by REA on 2017-12-10 at 12:22:36:

Wait! What?? Gravitational energy is negative energy? Ok, if I accept that how do you justify taking the next leap that this negative gravitational energy must exactly equal all the positive energy in the universe?

Regardless, I don't think I'll be joining any church (or religion) soon because science doesn't have all the answers or based on an alternate fantasy to which there is no credible evidence counters your admittedly fanciful speculations. Well, maybe the Pastifarians.

Comment 4 (4858) by OJB on 2017-12-10 at 17:46:03:

Gravitational energy doesnt *have* to equal the other energy but it does (or seems to accordomg to current observations). This must be significant in some way and might point to the origin or cause of the universe, which might be nothing since the energy is zero!

Yeah, I have been a follower of the IPU in the past, but the pirate aspects of Pastafarianism are very tempting (you get to say arrrrr! A lot). Maybe I will abandon the IPU and follow the FSM instead (please don't smite me with your holy hooves oh great IPU).

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