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.
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.
With infinite time will order spontaneously emerge from heat death?
Was Epicurus right?
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.
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.
https://physics.stackexchange.com/questions/200722/poincaré-...
(Obviously IANAPhysicist.)
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?
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).
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
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.
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.
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.
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!
https://en.wikipedia.org/wiki/Timeline_of_the_far_future
[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).
EDIT: Changed Fat to Far
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.
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.
0: https://en.wikipedia.org/wiki/Timeline_of_the_far_future#cit...
https://www.amazon.com/dp/0593171721/ref=cm_sw_r_sms_awdb_bt...
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.
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.
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?
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.
(Edit: adding refs)
https://en.wikipedia.org/wiki/Germ_theory_of_disease
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 could define myself as an atheist anyway so this is really a non issue for me)
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.
> "A fire-breathing dragon lives in my garage"
> "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.
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.
[1]That is, all animals have qualia.
https://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe#...
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.
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.
> 10^10^10^56: Time for quantum effects to generate a new Big Bang, resulting in a new universe.
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.
Also it might not be a given that events unfold in the same order, in each iteration.
It's explained in this PBS Space Time episode much better:
I ask since I haven't studied past a college-level modern physics course and have no ability to judge this kind of conjecture.
What is the experimental evidence for and against Penrose's model vs that of the string theorists (or other competing models)?
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.