There is no real information in this article. Roger Penrose has, as he himself puts it, a crazy theory that a universe existed before the big bang, and that the heat death of the universe starts a new big bang. That's the kind of chat you have over a few pints on the weekend, because there is nothing worth "media"ing about.
It's really not a crazy idea at all, though. It's certainly less crazy than how much of established scientific canon would've appeared to the world when it was originally proposed. I would argue most of quantum field theory is much "crazier" than Penrose's CCC idea.
That said, as far as I know it falls into the body of theories that struggle to make falsifiable predictions, and of the limited such predictions it has made nobody has found data that validates them in a statistically significant way yet.
Ok so a beer talk question to the physicists: By any measure of order, there are more disordered states than ordered states, and therefore any random change is likely to be a change to a more disordered state, leading to the inevitable heat death of the universe. But if this decent into chaos is only about probability, then given infinite time even the infinitesimal chance of spontaneous order will have it's moment.
With infinite time will order spontaneously emerge from heat death?
There's a theorem "Poincaré recurrence theorem" which says if a system is finite, given infinite time, it will return to a state arbitrarily close to its initial state.
While the theorem itself is well proven, I can't find a physicist who can say one way or another whether this applies to our universe.
My apologies, but I believe that this theorem applies to a subset of possible systems with certain properties which are called "conservative systems," not any arbitrary system.
The objection hasn't been made in your SE question, so I assume I am missing something, but why does 'if a system is finite' apply to the universe? The 'given infinite time' would need to be a 'faster' infinite than universal expansion?
The food on your plate is finite, but if you're served more faster (no slower) than you eat it, then you won't empty the plate even given infinite time.
The observable universe would have to be a conservative system for Poincaré recurrence to apply to it. I don't think that's possible; isn't it leaking matter that looks like it won't come back?
I don't understand all the properties a system must have so the Poincaré recurrence theorem applies, but as long as we don't know whether the (entire) universe is finite, that's sufficient to show that Poincaré recurrence may be impossible. In that situation, we can either find information that makes it impossible for sure, or otherwise we know that we don't know.
‘Nothing else can affect us‘ doesn't contradict that, because ‘us‘ would cease to exist at the Poincaré recurrence time (if not earlier).
N.B. I'm just pointing out some basic things, while having no clue how much merit the idea has in the first place, even if the universe has finite state space and infinite time. (I mean just the idea of trying to apply the Poincaré recurrence theorem to the whole universe, not Penrose's work.) AFAICT the proof only says that almost every state recurs infinitely often. So if you picked some state at random as your starting state, it's essentially guaranteed that it will recur, but when it comes to applying this to the universe, isn't it presumptuous to regard the big bang as such a state?
Assume that the volume of the visible universe grows, and then consider a ball that just circles on larger and larger circles. Clearly, the ball does not need to get back arbitrarily close to where it started.
I like your reasoning. Feynman pointed out why this doesn’t work: you have to “borrow odd”, so to speak, in order to get any effect. Which means that your slight perturbation, although miraculous, ends up having little more than an infinitesimal effect over an even smaller amount of time.
Feynman put it way better than me though. It was in the Messenger Lectures series if you’re curious. 6 wonderful and accessible videos; his audience was primarily laypeople, not scientists. Quite enjoyable.
Feynman's argument was about why you can't have systems that decrease entropy continuously. It doesn't disprove that there can (and will) be downward fluctuations in entropy, which is what I believe the OP was asking about. As someone else mentioned this is the idea behind a Boltzmann Brain (which is a pretty fascinating concept).
Heat death leads to absolute uniformity throughout the universe and when that happens, when no two points of the universe differ in any way, the universe becomes a single point and then a big bang occurs, according to Penrose.
Basically when all particles are moving at speed of light, time becomes meaningless and you can consider space to be infinitely small. I.e. identical conditions to Big Bang
> With infinite time will order spontaneously emerge from heat death?
The theory is more that with "infinite" expansion, the universe becomes so spread out as to in spot become emptier than the vacuum energy, and a new universe spontaneously erupts in that low energy locale. In a very small nutshell.
This relates to one of my favorite wikipedia pages: The Timeline of the Far Future.
The relevant part is at the end. Essentially, given enough time, quantum effects will result in an entire new universe spontaneously popping into existence. That time is ~10^(10^(10^56)).[0]
But, the number of ways that all particles in the universe can be arranged is only ~10^(10^115). That number is much smaller than the time to just go 'pop, new universe'. So, the much larger number also becomes about the time it takes to just have a new universe identical to our current one just go 'pop, new universe'.
The other entries in that article are just as joyously mind-bending. I really really love that page!
[0] Side note: The time for a 'Boltzmann Brain' (a consciousness that just floats in the infinite void thinking away, somehow) to spontaneously appear is only ~10^(10^50).
Also, I forgot to mention that all these timelines are in years.
But then I thought about it and about any human unit of time really doesn't change the numbers much at all. Heck, even measured as units of 'age-of-the-current-universe', the extra 0s just fade into the rounding errors very quickly.
To be clear here, that is stating that however you measure time pretty much has no meaning at these scales.
> But then I thought about it and about any human unit of time really doesn't change the numbers much at all.
As the Wikipedia page[0] puts it:
> Although listed in years for convenience, the numbers beyond this point are so vast that their digits would remain unchanged regardless of which conventional units they were listed in, be they nanoseconds or star lifespans.
>With infinite time will order spontaneously emerge from heat death?
The answer may be yes or no in any particular axiomatization (model) of the physical laws, but depends strongly on the choice of model. Unlike a normal situation, when we talk about very-low-probability effects we are subject to any influence of "quantum gravity" and other "new/unknown physics" that may have a finger, however light, on the scale.
In the Standard Model I think the answer is yes, but we are already aware of some deficiencies (neutrino transitions).
> then given infinite time even the infinitesimal chance of spontaneous order will have it's moment.
Does this hold true for a 1/infinity chance event?
Or (not sure if this is analogous) if you choose infinitely many real numbers ~ unif(0, 1), is it guaranteed you will hit every number in that interval at least once? I'm not even sure the question is well-defined to be honest (at least not without making assumptions about infinities that we have no way to show hold true for this universe), but if it is, is the answer yes? It's not obvious to me.
The first is not well defined, the second is and as long as we are talking countable infinity, it is not. (In the uncountable case you are running into problems with definitions again.) As a matter of fact, you will not hit almost all numbers. However, you will almost surely have picked a point in any fixed interval, and that is meant with order reapers over long enough timescales.
For illustration, you are almost guaranteed to not win the lottery, but when you play again and again, then after something like 14 million times playing (for the German Lotto) you will win, and again after something like 28 million times playing, and so on, so you expect to often over long enough timescales, and you can start to impose additional constrains, for example winning with consecutive numbers, or the first few primes. And after a long enough timescale you start to win again with these additional constrains.
For example a complete brain capable of imagining it’s in a universe could spontaneously occur... (Boltzmann brain) but the catch is that there needs to be enough usable energy for it to function. So even if order suddenly occurs, heat death means an eventual limit to complexity.
Ultimately something needs to happen to cause a sudden reverse into very low entropy, ie another Big Bang or something of the like.
We’re talking like 10^50 years here before heat death ends thought so... the universe has some time still.
This is the Boltzmann Brain paradox -- given this probability system, it's much (not going to say infinitely... but practically so) more likely that your perception of this moment is a fluctuation in chaos than that the entire universe as you perceive it currently exists. The parallels to the simulation argument/doomsday hypothesis are, I hope, apparent.
> It's really not a crazy idea at all, though. It's certainly less crazy than…
When someone comments on the craziness of theories about before the big bang (and therefore the cause to which it was an effect), it is always worth remembering that the big bang itself was considered crazy by many initially.
The name even came from a dismissive description (with massive vocal air-quotes around "big bang") that just stuck as it is actually a good description (at least by dint of being catchy).
Crazy does not necessarily mean something is incorrect.
It really is. Every physicist has a dozen ideas like that they realize are stupid, have no evidence for and can't really be proven or disproven with current data.
We call them crazy to keep our selves from going off the deep end and talking about ufos, the foundations of mathematics or the genetic differences between races.
I'm kind of shocked there's nothing on the front page about Penrose winning the Nobel prize for physics. The guy is really a polymath, even accounting for his outlandish and sometimes discredited theories.
Even so, his black hole theory also had a long time coming to acceptance. What he says might be hard to prove, but it doesn’t sound totally absurd, and probably also isn’t an uneducated guess by someone who knows the math.
> a crazy theory that a universe existed before the big bang, and that the heat death of the universe starts a new big bang.
I realize this isn't what Penrose is saying, but is it really that crazy that random fluctuations will create the conditions for a new big bang in a universe at thermal equilibrium?
It's not useful to speculate about things that are unfalsifiable. That's why Penrose wants these things to be observable traces from before the big bang.
> It's not useful to speculate about things that are unfalsifiable.
I disagree. While such speculation obviously won't produce immediately useful data, where would we be today if noone had ever speculated about something which at the time could not be falsified? Case in point: the initial speculation on the existence of germs, which at the time was unfalsifiable.
From the arcticle: "By the early nineteenth century, smallpox vaccination was commonplace in Europe, though doctors were unaware of how it worked or how to extend the principle to other diseases."
So doctors were saving lives even though they had no idea exactly how or why it worked. They could neither prove nor disprove why it seemed to work, it simply did. The fact that it was unfalsifiable had nothing to do with the truth of the matter - it still saved lives.
I think there's a difference between untestable in practice, right now, and unfalsifiable even in theory. The latter case can never hold any practical value.
I think the point dumpsterdiver is making is that determining what is falsifiable or not is context/time dependent. As our understanding of reality changes over time so does our definition of what can be falsifiable.
> "Show me," you say. I lead you to my garage. You look inside and see a ladder, empty paint cans, an old tricycle--but no dragon.
> "Where's the dragon?" you ask.
> "Oh, she's right here," I reply, waving vaguely. "I neglected to mention that she's an invisible dragon."
> You propose spreading flour on the floor of the garage to capture the dragon's footprints.
> "Good idea," I say, "but this dragon floats in the air."
> Then you'll use an infrared sensor to detect the invisible fire.
> "Good idea, but the invisible fire is also heatless."
> You'll spray-paint the dragon and make her visible.
> "Good idea, but she's an incorporeal dragon and the paint won't stick."
> And so on. I counter every physical test you propose with a special explanation of why it won't work.
> Now, what's the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all?
> If there's no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists?
> Your inability to invalidate my hypothesis is not at all the same thing as proving it true.
> Claims that cannot be tested, assertions immune to disproof are veridically worthless, whatever value they may have in inspiring us or in exciting our sense of wonder.
Well, if the dragon exists it must have the characteristics of a dragon. Let's say it must be an animal with four legs and a tail. Currently it's unknown whether all animals are q-conscious[1]. Let's say it is discovered that all animals are q-conscious. Therefore the invisible dragon is q-conscious.
Currently we don't really understand qualia, but one mainstream theory is that qualia are a different kind of thing to anything else we know about (i.e. are non-physical).
Let's say this theory is true, and, further, that a method for detecting this different kind of thing is detected. That the dragon is invisible, floats, is heatless, is incorporeal, doesn't matter.
The theory that there is a dragon in the garage is falsifiable by the observation that a scan for qualia results negative.
You could say "ah, but this dragon is the dragon of any-test-you-can-come-up-with-doesn't-work, therefore you can't come up with any test which would work". But that would be begging the question.
If you've not yet experienced H2G2 I suggest tracking down the original radio version before the books, TV, or more modern film - it is widely available to buy in various formats. It is justly recognized as a classic.
It seems not only has he made multiple predictions based on this theory, but he also is actively publishing research showing it may be true. Where do you get unfalsifiable from? There’s literally falsifiable claims being made.
There are a lot more books sold on speculative fiction than real astronomical insights. Clearly, such speculation serves a purpose and must therefore be considered useful.
A couple of theories regarding the ultimate fate of our universe are the Big Crunch (everything comes together) or the Big Freeze (everything drifts apart, forever). I agree that it's not hard to imagine that if a Big Crunch happened it could potentially create another Big Bang. That said, there's still no way to necessarily prove that.
I feel like this is a good time and place to bring up an idea that I sometimes like to entertain. It goes like this:
There is some number of dimensions that exist in total, which is a number higher than just the four dimensions that we are readily able to observe. Our universe exists within this higher dimension, alongside other universes.
Also, what we perceive as linear time within our universe might not be just a single dimension either. But even if it's not we can still treat it as though it was.
The laws that apply within each of these four dimensional universes as we might see them might or might not all be the same laws. I.e. all other universes might have the same laws as does ours, or some might be different, or all might be different. We can't know.
But the idea that I like to entertain is that these universes could serve some function within the higher dimensions.
For example, a set of many many parallel universes might each function analogously within the higher dimensions as to how cells function in our universe, and that analogously these parallel universes form a greater whole together as some sort of being that is made up of all of these.
Or another possibility might be that a universe could be able to develop within itself life that is able to sense the higher dimensions, and to break free of the universe within which it was created and to then continue existing in the higher dimensions beyond the end of the universe that created it. I imagine this not as human with more senses, but something very different. For example, the way it might come into existence in our universe could be through machinery that we create, with mechanical sensors that are able to pick up the other dimension(s), and with increased computational power the machines we create could in turn process all of the information available to it in order to construct something that somehow (yes, very vague sorry) is not limited by the reality of our universe itself.
But yeah, there is no scientific basis for said ideas. It's just something that I like to imagine.
It’s quite fun to speculate. If you’re into this sort of thing, you’d like lemmino on YouTube. Pick any one of his deep dives and you’ll end up listening to something pretty close to what you did here: speculation, in a tight straight jacket.
Part of the problem with dark energy is that so much of it is unfalsifiable in ways similar to these theories. Of course, the key difference is that we can measure the effect dark matter has on the universe, whereas thus far no more than 4 dimensions have ever been observed.
Sure makes drinking fun though. Take a sip and say a hypothesis. Like apples to apples but for physicists.
If I were having a pint with Penrose, I'd take it a step crazier: what if the earlier universe is actually this one? And our universe ends up in a Big Bang, which begets a new universe, which is the one we are now in.
According to CCC and to my understanding, it is sort of the case. The universe has undergone a "scale change" which marks the beginning of a new Epoch.
It's explained in this PBS Space Time episode much better:
If that's the case, then wouldn't we have some kind of special background radiation? Penrose stated that some things must be visible through background radiation right? (something with black holes of the preveious aeon)
If that's the case, then we might be able to observe that state and try to workout, whether we get to that same state.
There's BBC Horizon episode called "What happened before the Big Bang?" where Penrose stated that he used t to kinda roll his eyes when people asked what happened before because the question didn't make sense.
The whole episode is a wild ride including people from the Perimeter Institute proving soon to me how bizarre theoretical physics is at its frontier. Highly recommended watch.
Yeah Penrose idea is logical but then very vague on the proof side.
It obvious we re misrepresenting reality by saying it started with a big bang, and there must be a simple way out of infinite looping or creation from the void in higher dimensions.
But I stopped dreaming with Penrose because it always just stop at "but this is all just me saying it" kind of.
