Can the Universe Cause Itself to Exist from a Physics Perspective?

[celebrei]

I was wondering from a physics point of view if it is plausible for the universe to have caused itself to be...

 

[Phyisab****]

In my opinion, this is purely the realm of philosophy. I would love to hear opinions otherwise...

 

[Chronos]

Sean Carroll once wrote a paper to that effect. Apparently he since withdrew it. I believe Max Tegmark has also speculated on it as well. The theory goes that the universe arose from a quantum fluctuation in whatever state existed a prior to that. It is as good as any a priori theory of how the universe arose. It appears likely the universe did not always exist, so it is fair game for speculation.

 

[DevilsAvocado]

Catch-22
I can’t tell about the physics, but logical it must be – No.

If something is able to 'create' something, it must be present first, right? Either the universe 'existed' before it 'existed' (Catch-22)...!? Or, it did not create its own 'existence'.

Nevertheless, the evidence is overwhelming for a 'massive event' 13.8 billion years ago, that expanded into what we see today.

So what happened? Well, before we get GR = QM it seems hard to explain mathematically. Other possibilities might be; a Big Crunch, or colliding Branes, or a Multiverse where the 'bubbles' sometimes collide (or grow into each other’s 'territory'), or something completely new that no one haven’t thought of yet.

I have absolutely no idea...

But the real exciting question is: Will we live until the 'mystery' is solved?

My guess is – Yes!

Note1: I know – 'existence' is awkward word for the universe.
Note2: I don’t believe in god or any other 'intelligent designer'.

 

[BlackHole213]

The universe is either opened or closed. An open universe means that there has only been one Big Bang and the universe will keep expanding until it eventually dies hundreds of trillions of years from now.

A closed universe is when the universe keeps expanding but will eventually get back to its starting position. For example, assume that a person leaves Boston traveling to the east in a straight line. The person will travel around the world and eventually will get back to his starting position, Boston. For the universe to do this, assume that the universe keeps expanding just like the person kept on travelling. Eventually, the universe could reach its starting position, thus causing the death of the current universe but the creation of the next one instantly through another Big Bang.

You must keep in mind, though, that these are only theories. There is no way to prove either of them true or false with today's technology. As Phyisab**** said, "this is purely the realm of philosophy." And this concept will continue to be "a relm of philosophy" until someone proves that the universe is either opened or closed.

Therefore, the answer to your question, in one word would be "yes"

 

[Dmitry67]

A closed universe is when the universe keeps expanding but will eventually get back to its starting position.

No.
If there is enough Dark Energy, Universe can be closed, but expanding forever.
What you are explaining was correct before the discovery of DE

So DE adds 2 more options:
1. Closed but expanding forever
2. Big Rip option

 

[BlackHole213]

I've heard of dark energy but I don't really understand it. Could you explain dark energy and how it contributes to the universe?

 

[marcus]

...A closed universe is when the universe keeps expanding but will eventually get back to its starting position. ...

No. Dmitry explained why you are wrong. The possibility of a universe that is spatially closed but which expands forever has always been a part of the theory ever since Einstein wrote down the basic equation (around 1917?) with a cosmological constant Lambda.

Simplified popular accounts (and beginning textbooks!) tended to ignore this possibility and assume that Lambda was zero---many continued doing this until around 1998 when evidence of accelerated expansion was discovered.

Accelerated expansion means that the simplified equations with zero Lambda must be wrong. We have to allow for a spatially closed universe (e.g. a hypersphere, analogous to the surface of a balloon but 3D instead of 2D) which expands indefinitely.

Dark energy has been discussed a lot at this forum. You might search for it and find some earlier threads. If Dmitry wants to give you an introduction, however, that would be great.
His explanation is apt to be both more concise and clearer than what I could provide at the moment.

 

[marcus]

I was wondering from a physics point of view if it is plausible for the universe to have caused itself to be...

An additional question: if you imagine that it did cause itself, is when did it do so?

Plausibility tends to be in the eye of the beholder. There are on the order of 10 schools of thought about what preceded the big bang (the start of expansion). On the order of 100 scientists currently researching and writing papers exploring the various models of how expansion could have started---studying various "before-the-big-bang" pictures.

There is a book supposed to be coming out, collecting and comparing all these various ideas.
Different leading experts contributing chapters. I have seen the table of contents and read some of the chapters, but I haven't seen the whole book. It is not out yet (in fact there have been several delays.) Based on what I have seen, I don't like the book. (But could change my mind, I suppose, when I see the whole thing in final version.)

It does seem to have at least one chapter that considers what you might think of as "self-creation", but I can't say how seriously that is taken nowadays.
There are so many other ideas which are more concrete, more physical. And some may be testable in the sense that the way expansion started could have left an observable imprint on the distribution of matter and radiation.

As long as these concrete ideas are on the table, for understanding how expansion started, it seems unnecessary to spend time with anything as speculative and philosophically bizarre as self-creation. My attitude anyway, you may feel differently.

In case anyone is curious, here's a link to the publisher's page about that book:
http://www.springer.com/astronomy/general+relativity/book/978-3-540-71422-4
It gives a link to the table of contents, and another link to some reviews, and it gives a list of keywords---which indicates some of the topics covered in the various 20-odd chapters:

==quote from publisher's page, warning: contains blurb==
"The stellar line-up of contributors to this volume are working at the cutting edge of cosmological research, and are poised to take our understanding of the universe beyond the big bang into an even stranger realm." -- Paul Davies
"This book provides a wonderful overview of current ideas on these ultimate cosmic questions, written by scientists working at the forefront of cosmological research."-- Alex Vilenkin

Written for:
Popular/general

Keywords:
Anthropic Principle
Before the Big bang
Big Bounce
Cosmic Inflation
Cosmic Initial Conditions
Cosmic Natural Selection
Cyclic Universe
Eternal Inflation
Holographic Universe
Island Cosmology
Loop Quantum Gravity
Quantum Cosmology
String Cosmology
String Landscape and Multiverse
...
==endquote==

 

[DevilsAvocado]

The most important (< 1998) parameter in fate of the universe is the Density parameter, Omega (Ω), defined as the average matter density of the universe divided by a critical value of that density.

Omega (Ω) related to the curvature of space (global geometry, all forms of dark energy are ignored):

Ω > 1 positive curvature, spherical universe, Closed
Ω < 1 negative curvature, hyperbolic universe, Open
Ω = 1 zero curvature, flat universe, Flat

A closed universe (Ω > 1), lacking the repulsive effect of dark energy, gravity eventually stops the expansion of the universe, after which it starts to contract until all matter in the universe collapses to a final singularity, "Big Crunch". However, if the universe has a large amount of dark energy (as suggested by recent findings), then the expansion of the universe can continue forever.

An open universe (Ω < 1), even without dark energy, expands forever, with gravity barely slowing the rate of expansion. With dark energy, the expansion not only continues but accelerates. The ultimate fate of an open universe is either "Heat Death", "Big Freeze", or the "Big Rip".

In a flat universe (Ω = 1), average density of the universe exactly equals the critical density. Without dark energy, it expands forever but at a continually decelerating rate, approaching a fixed rate. With dark energy, the expansion rate of the universe initially slows down, due to the effect of gravity, but eventually increases. The ultimate fate of the universe is the same as an open universe.

The options then are:

• Big Freeze
• Heat death
• Big Rip
• Big Crunch
• Big Bounce
• Multiverse (no end)
• False vacuum (destroyed instantaneously)

As an 'answer' to OP, the only options (as I see it) not demanding a 'caused start', is the Big Bounce, and maybe Multiverse...

 

[DevilsAvocado]

... The theory goes that the universe arose from a quantum fluctuation in whatever state existed a prior to that. It is as good as any a priori theory of how the universe arose. ...

And if BB is proved a onetime event, then the obvious question is – So what created "whatever state existed a prior to that"...??

And we’re back to Catch-22 again... a philosophical loop without a logical end...

In my opinion, the best thing to do is to wait for science to (hopefully) discover a theory that takes us all the way back to t0. And then hope that this 'TOE' is 'self-explainable', in case of t0 as the absolute first 'moment' in all spacetime... if we are lucky...

 

[Chronos]

In a temporally finite universe, the issue of a beginning is inescapable. Whether that beginning is literal is open to interpretation. This universe could be a temporally finite patch on the surface of a much larger [perhaps infinitely large] region that is unobservable to us. Deriving the value of omega is an important goal of modern cosmology. If it turns out the universe is closed, it is almost certainly finite in time and space. If not, it is probably infinite in both regards.

 

[Dmitry67]

In a temporally finite universe, the issue of a beginning is inescapable.

No, I can provide an example.
"Big bounce" scenarios, for example. Universe contacts from infinity, bounces, and exands again. I really don't like the interpretation that Universe "contracted", because it requires some magic event when entropy suddenly decreased.

I think it is much more easier to interpret the contraction as expansion, so entropy decreased all the way down to the BB. It means, that for all observers in such Universe time time flowed FROM the BB, like in ours. So it is a symmetrical double-sided BB.

In MWI, as all possibilities exist, it means that wavefunction of the universe, "omnium", O(t) is an even function, O(-t)=O(t), so both sides are identical -> they are the same.

 

[Chalnoth]

Catch-22
I can’t tell about the physics, but logical it must be – No.

Nope. Self-causality is certainly strange, but it is not illogical. That is to say, there doesn't appear to be any logical contradiction posed by the possibility of self-causation. It is definitely strange, however. In quantum mechanics, one could see loop contributions to Feynman diagrams as being self-caused.

 

[DevilsAvocado]

Nope. Self-causality is certainly strange, but it is not illogical. ...

Okay (warning I just finished a full course at the http://www.youtube.com/watch?v=kQFKtI6gn9Y" ), so how does one explain this 'little' dilemma:

If BB is a single event, and time and space were 'created' at t0 – How is it possible for QM/Feynman diagrams to 'choose' a moment, 13.8 billion years ago, to cause its own 'creation'? If there is No time – there are obviously No moments to 'choose' for a start... right??

 

[Dmitry67]

What created (caused) number 7?

 

[DevilsAvocado]

Number 3 & 4 ...?

 

[DevilsAvocado]

No, I can provide an example. "Big bounce" scenarios, for example.

I absolutely agree.

I really don't like the interpretation that Universe "contracted", because it requires some magic event when entropy suddenly decreased.

Agree. Or as http://bloggingheads.tv/diavlogs/21709?in=27:40&out=30:00": "If you took our universe today and you let it collapse, instead of winding the clock backwards, you just reversed its expansion and let it collapse – it would not undergo the time-reversal of the ordinary evolution of the universe from early to late – it will be very very different!"

I think it is much more easier to interpret the contraction as expansion, so entropy decreased all the way down to the BB. It means, that for all observers in such Universe time time flowed FROM the BB, like in ours. So it is a symmetrical double-sided BB.

I don’t get this at all... how can contraction be 'interpreted' as expansion... to me this is running time backwards, even in MWI...

But couldn’t one explanation to the very special initial conditions at BB be 'some new' physics at Planck time, that we yet don’t understand... i.e. in a "Big Bounce" the universe starts to collapse, and when GR breaks down at Planck time, some 'new processes' comes in and reorder the entropy into a level that a new BB can occur, and this is then repeated infinitely...? Or is this just 'layman science fiction'...?

Another possibility (maybe) can be that for every "Bounce" there’s completely new/different initial conditions, thus every BB creates a completely unique (laws, particles, etc) universe...

 

[Chalnoth]

Okay (warning I just finished a full course at the http://www.youtube.com/watch?v=kQFKtI6gn9Y" ), so how does one explain this 'little' dilemma:

If BB is a single event, and time and space were 'created' at t0 – How is it possible for QM/Feynman diagrams to 'choose' a moment, 13.8 billion years ago, to cause its own 'creation'? If there is No time – there are obviously No moments to 'choose' for a start... right??

Why not ask that question for a nuclear decay? How does, for instance, a Uranium 238 nucleus 'choose' one moment to decay as opposed to another?

 

[DevilsAvocado]

Why not ask that question for a nuclear decay? How does, for instance, a Uranium 238 nucleus 'choose' one moment to decay as opposed to another?

I think you misunderstood me, and/or vice versa.

Uranium 238 decay is cool. The random nature of QM (and absence of cause) is cool. HUP is cool, because: There already is a framework where these phenomena can operate/progress – Space+Time.

This problem is quite simple, and has nothing to do with cause or QM or anything like that. It doesn’t matter if it’s Feynman, Einstein, Shaman, Bhagavan, or any other distinguished gentleman – they all have the same 'single' problem:

Feynman – "I want to run 100 meters."
Einstein – "Sorry Dick, I’m not going to let you do that..."
"Why?"
"Because we don’t have any meters in this place..."
"What!?"
"Nope..."
"Ehh screw it… I’m going to let my QM foam out NOW... so the QFT and my diagram can start The Universe randomly without a cause... so I can get a drink and my Nobel Prize later... 13.8 billion years later..."
"Not going to let you do that either..."
"What!? Why!?"
"Because you don’t have any time, and thus no NOW, to do it..."
"Say What!? Time is all we got in this darned place!"
"Sorry Dick, no time and no space... it’s just you & me, and the virtual eternity..."​

Get it?

 

[Chalnoth]

I think you misunderstood me, and/or vice versa.

I merely pointed out that in quantum mechanics, there are a large number of events that are "uncaused" in a sense: they have a certain probability per unit time of occurring, but they don't occur at a certain time because of a certain event.

It's not difficult to imagine that this process might well extend to space-times in quantum gravity.

 

[DevilsAvocado]

I merely pointed out ...

It’s cool, I misunderstood you. So, any thoughts on the "Feynman-Einstein dialog", right or wrong?

 

[celebrei]

I merely pointed out that in quantum mechanics, there are a large number of events that are "uncaused" in a sense: they have a certain probability per unit time of occurring, but they don't occur at a certain time because of a certain event.

It's not difficult to imagine that this process might well extend to space-times in quantum gravity.

Correct me if I'm wrong but quantum mechanics doesn't allow for an event without a cause and even virtual particles occur because the potential for their occurrence is contained in the relevant lagrangian, what QM does allow is a cause w/o necessarily an effect eg: throwing a particle at a barrier may or may not cause it to reflect back

 

[Chalnoth]

It’s cool, I misunderstood you. So, any thoughts on the "Feynman-Einstein dialog", right or wrong?

I don't understand at all what you were getting at.

 

[Chalnoth]

Correct me if I'm wrong but quantum mechanics doesn't allow for an event without a cause and even virtual particles occur because the potential for their occurrence is contained in the relevant lagrangian, what QM does allow is a cause w/o necessarily an effect eg: throwing a particle at a barrier may or may not cause it to reflect back

Well, there is a cause in the sense that there are laws of physics which provide the potential for certain interactions to occur, and so they do with some frequency. It isn't difficult to imagine that the same sort of thing might occur for space-times. This isn't the same cause-and-effect relationship, though, as it's not a matter of some event occurring which causes some other event. Instead it's just that X happens because the laws of physics are a certain way. So self-caused is perhaps a somewhat better description than uncaused (e.g. in the instance of a virtual particle, virtual particles appear because they have certain interactions with other bits of matter).

 

[DevilsAvocado]

I don't understand at all what you were getting at.

Hehe, I don’t blame you. This is my very personal 'view' of this problem...

Theoretical physicist use math to understand the universe, and some say mathematics is the core foundation of the universe (and everything). If we look at the start of BB, from the view of a mathematician, I guess I will look something like this, with t0 at 0:

In this field of view, it’s not hard to imagine random QM fluctuations to start the BB. There’s a statistical QM possibility at A, but nothing happens. There’s a statistical QM possibility at B, but nothing happens. There’s a statistical QM possibility at C, and now something happens (without a cause) - Big Bang starts!

Now let’s take a step back and reconcile what we are discussing, in case BB was a onetime single event:

• Before BB/t0 there was absolutely nothing.
• Before BB/t0 there were no space and no time.
• Before BB/t0 there were no laws of physics.
• Before BB/t0 there were no QM fluctuations.
• Before BB/t0 there were no mathematics (including number 7, I know Dmitry67 doesn’t agree ).
• Before BB/t0 there were no metrics.

With these statements in mind, the infinite/eternal 'epoch' preceding BB would look something like this (to me):

Or maybe better, like this:

So, the big mystery to me is – How can QM fluctuations 'chose' a random 'moment' in an 'epoch' where there was no time, no moments, no metrics, no laws, no QM...!? To start something like this 4-dimensional space:

I think this elegant quote of Albert Einstein, expresses the core of this problem:

"The only reason for time is so that everything doesn't happen at once."​

Thus rationally, if there is no time – everything must happen at once, or it doesn’t happen at all...

Hopefully I’d explained this 'mad idea' well enough this time, or...?

 

[Chalnoth]

This is a fundamental problem with quantum gravity, however: in quantum gravity, we expect space-time to be quantized. Fundamentally this means that we have to find a way of describing space and time as emerging from the quantum behavior of the system. This means that we have to find a way of describing the quantum behavior of the system without using either space or time.

If we can discover a way to overcome that particular conceptual hurdle, then maybe it will make perfect sense how a universe could randomly appear out of nothing.

 

[Dmitry67]

This is why I like MUH - it answers all such questions (by making all them meaningless :) )

 

[DevilsAvocado]

... This means that we have to find a way of describing the quantum behavior of the system without using either space or time.

If we can discover a way to overcome that particular conceptual hurdle, then maybe it will make perfect sense how a universe could randomly appear out of nothing.

Thanks a lot Chalnoth! This kind of extremely interesting information makes me serious wonder if I did chose the wrong occupation...!?

You must keep this forum up to date, in case 'something' happens!

BIG THANKS!

Edit: And it for sure feels reassuring that this was not only a personal 'mad idea'...

 

[DevilsAvocado]

This is why I like MUH - it answers all such questions (by making all them meaningless :) )

LOL

 

[Chalnoth]

Thanks a lot Chalnoth! This kind of extremely interesting information makes me serious wonder if I did chose the wrong occupation...!?

You must keep this forum up to date, in case 'something' happens!

BIG THANKS!

Edit: And it for sure feels reassuring that this was not only a personal 'mad idea'...

Hehe.

Unfortunately, though, I strongly suspect that it will be quite a while before we have a solid quantum gravity theory.

 

[DevilsAvocado]

... Unfortunately, though, I strongly suspect that it will be quite a while before we have a solid quantum gravity theory.

Good things come to those who wait, and time is relative, Albert says...

 

[DevilsAvocado]

... then maybe it will make perfect sense how a universe could randomly appear out of nothing.

Ops! It seems like we have a hard-nosed opponent to our beautiful quantum fluctuations in https://www.physicsforums.com/showthread.php?p=2545870#post2545870"... I see sparkles and I smell blood...

 

[xantox]

I was wondering from a physics point of view if it is plausible for the universe to have caused itself to be...

It is a speculation at least consistent with general relativity. A well known model of "self-creating" inflationary universe has been proposed by J. R. Gott and L-X. Li, "Can the Universe Create Itself?", Phys. Rev. D 58, (1998).

 

[Dmitry67]

There is a difference between multiverse creating sub-universes (via BH, or brane collisions etc) and "universe caused itself"

 

[DevilsAvocado]

It is a speculation at least consistent with general relativity. ...

Objection 1: GR will not take you all the way down to t0, it will break down at Planck time. So how can GR explain what caused the universe?

Can the Universe Create Itself?
Authors: J. Richard Gott, III, Li-Xin Li
(Submitted on 30 Dec 1997)

The question of first-cause has troubled philosophers and cosmologists alike. Now that it is apparent that our universe began in a Big Bang explosion, the question of what happened before the Big Bang arises. Inflation seems like a very promising answer, but as Borde and Vilenkin have shown, the inflationary state preceding the Big Bang must have had a beginning also. Ultimately, the difficult question seems to be how to make something out of nothing. This paper explores the idea that this is the wrong question --- that that is not how the Universe got here. Instead, we explore the idea of whether there is anything in the laws of physics that would prevent the Universe from creating itself. Because spacetimes can be curved and multiply connected, general relativity allows for the possibility of closed timelike curves (CTCs). Thus, tracing backwards in time through the original inflationary state we may eventually encounter a region of CTCs giving no first-cause.​

Objection 2: I’m a layman and may be wrong, but everything I've read so far says: First the extreme singularity at t0, then the 'Big Bang', and then Inflation...??

Objection 3: To me this seems like a very easy way out (almost silly) – not to explain how something came out of nothing, and instead try to prove that inside this universe there aren’t any laws preventing this phenomena!? Que? The physical laws of this universe apparently didn’t exist before the universe... AND the universe is here, isn’t it!? I mean – what will happen if they can prove that there is a law that makes the universe 'illegal'??

 

[Chalnoth]

Objection 2: I’m a layman and may be wrong, but everything I've read so far says: First the extreme singularity at t0, then the 'Big Bang', and then Inflation...??

The singularity in the big bang theory is known to be wrong. By "before the big bang" they mean before the big bang theory was valid. The big bang theory is not valid at the earliest of times.

While inflation must have had a beginning, an actual singularity is a physical impossibility.

Objection 3: To me this seems like a very easy way out (almost silly) – not to explain how something came out of nothing, and instead try to prove that inside this universe there aren’t any laws preventing this phenomena!? Que? The physical laws of this universe apparently didn’t exist before the universe... AND the universe is here, isn’t it!?

Basically, it appears to be the case that in the context of quantum mechanics, everything that is not expressly forbidden necessarily occurs. To supply a small analogy, consider quantum electrodynamics. In QED, we find that photons have the potential to exist everywhere in space-time. And merely because they have the potential to do so, they necessarily pop in and out of the vacuum all the time. Space-times might well follow a similar principle.

I mean – what will happen if they can prove that there is a law that makes the universe 'illegal'??

Then that law is a contradiction and must be false.

 

[DevilsAvocado]

... And merely because they have the potential to do so, they necessarily pop in and out of the vacuum all the time. Space-times might well follow a similar principle.

Thanks for the explanation Chalnoth, I’m glad you’re out there.

I have been thinking a little bit more about (almost the same thing) what you said last time:

"then maybe it will make perfect sense how a universe could randomly appear out of nothing"​

We see virtual particles popping out (and in) of vacuum in the universe. This is a 'sign' of "how something can come out of nothing", right? And if this happens here, its not impossible it happened for the whole universe 13.8 billion years ago, right?

But, has anyone seen the 'laws of nature' popping out of nothing? Or any constants, like the 'weird' fine-structure constant (α = 0.08542455), or is this a completely unintelligent question...? That is... the laws and constants are 'embedded' in the particles, i.e. they 'know' what rules are present...

OMG... I don’t know what I’m talking about... 'laws' in vacuum...

 

[Chalnoth]

Laws don't appear or disappear, however. They simply are. Where this is concerned, I think that Tegmark's mathematical universe hypothesis is perhaps the most reasonable.

 

[DevilsAvocado]

Laws don't appear or disappear, however. They simply are. Where this is concerned, I think that Tegmark's mathematical universe hypothesis is perhaps the most reasonable.

Okay, that means Dmitry67 (MUH) is right after all?

 

[Chalnoth]

Okay, that means Dmitry67 (MUH) is right after all?

He hasn't said enough as to what he means with regards to the Mathematical Universe Hypothesis for me to offer a judgment either way.

 

[DevilsAvocado]

Chalnoth, about the Mathematical Universe Hypothesis, I must admit that I have very hard time to digest this way of looking at the physically reality... but it’s maybe a result of my 'status'...

To me, it’s pretty clear that humans don’t know everything, and (probably) never will. The 'thing' we call science is, and always will be, an approximation of what really goes on in nature. And mathematics is just a tool in this process, created by humans to make it graspable, not a 'divine thing' that created everything...

A classical example is QM. The mathematics works extremely well, and we build everyday functional machines on this knowledge. But is mathematics in QM really the hard blueprint of what really goes on at this level...?? It’s maybe stupid of me to speak in this matter - but my 'gut feeling' says no...

Tegmark's postulate is: All structures that exist mathematically also exist physically.
If we turn this around: All structures that exist physically exact also exist mathematically exact.

Is this true? I say no. Just look at ∏ ...

And what happens if String theory is proven wrong? What are all these new mathematical structures then, existing or non-existing physically?

What’s your opinion?

 

[Chalnoth]

Well, the thing is that we don't yet have any sort of theory of everything. In fact, we know that our current physical theories are necessarily just approximations to the true behavior (because they have various places where the mathematics become nonsensical).

The mathematical universe hypothesis isn't a hypothesis that we already know the mathematical structure that is our universe, but rather that there is one out there. Tegmark goes into a good argument for why this is reasonable, but in the end it boils down to simply this:

1. A mathematical structure is just a fully-consistent set of rules.
2. If our universe is fully consistent, then it is isomorphic to some mathematical structure (which we don't yet know). This would indicate that at least some mathematical structures have real existence.
3. It is generally easier for all things of a class to exist than for only some of them to, so it is simpler to propose that all mathematical structures exist.

 

[Dmitry67]

He hasn't said enough as to what he means with regards to the Mathematical Universe Hypothesis for me to offer a judgment either way.

I just agree with Max Tegmark, so you can take his article

P.S.
Just read...
Your 1-2-3 is the shortest summary of Max article I've ever seen, very nice, cool!

 

[DevilsAvocado]

Chalnoth, I agree with Dmitry67, your 1-2-3 is very nice, and short enough to make sense even to me.

So, if a bright and young new 'Einstein' one day exclaims Eureka TOE! The guessing is over, and the speculation if mathematics is the real isomorphic mirror of reality, or just an approximation-tool of humans, has come to an end:

Mathematics is the physical reality, and the physical reality is mathematics.

Cool!


It’s also very exciting (for Tegmark) if the real nature of the physical reality turns out to be the QM-wayward-statistical-not-open-the-box-all-the-way structure...

 

[Dmitry67]

Even if many scientists do now believe in the alternative universes, I think it is very important to study them for the better understanding of ours and for the A.P. below I put a list of the questions about the alternative universes. They are very deep and difficult, but at the same time it is NOT pure phylosophy, they are quite rigorous:

Take all parameters of the Standard Model, add density of DM, DE, gravitation. In this about 30-dimension space there is an 'island of observer-friendly universe'

1. How big is that island?
2. How close are we to the border of that island? are we at the center of not?
(more difficult)
3. Are there any other islands?

(now even more difficult, assuming, at least for some time, that MUH is true and all sorts of universes with different laws exist)
4. What are the requirements, in general, for an observer-friendly universe? (what mathematical systems are observer-friendly - note: that question can be studied by pure mathematics, but I think it require a theory of consciousness)
5. Is our universe the simplest observer-friendly universe or not?
6. Are there any better universes?
7. Can we somehow transfer our consciousness into such universes?

 

[Chalnoth]

For point number four, I think we'd just go for the most basic requirements today: you have to have stars that make heavier elements. This implicitly requires significant structure formation as well. I don't think we could do better than this simple requirement any time soon.

 

[Dmitry67]

Yes, but what's about universes without stars at all, so different from ours but still observer-friendly? Or universes with more then 1 time dimension?

 

[Chalnoth]

Yes, but what's about universes without stars at all, so different from ours but still observer-friendly? Or universes with more then 1 time dimension?

The reason why stars are important is that they are needed to produce the heavier elements that are required for complex chemistry.

And a universe with more than one time dimension has some nasty features that make such a thing highly unlikely, such as closed timelike loops.

 

[Dmitry67]

1. Yes, in OUR universe stars are important, I know. But imagine Universe where energy is not conserved. Observers there can develop on isolated blobs of matter, they won't need a central star. Now say heavier elements in their chemistry are developed during thir BB (like some part of our helium) - et voila, they don't need stars

2. unlikely? or difficult to imagine? :)