Universe: Finite or Infinite?

DevilsAvocado

Okay, now I'm really confused...?

Wikipedia - Copenhagen interpretation - Nature of collapse
"So if an electron passes through a double slit apparatus there are various probabilities for where on the detection screen that individual electron will hit. But once it has hit, there is no longer any probability whatsoever that it will hit somewhere else. Many-worlds interpretations say that an electron hits wherever there is a possibility that it might hit, and that each of these hits occurs in a separate universe."

Is it my brain that has split into impossible many QM-states?? Or... isn't the Copenhagen interpretation <> Many-worlds interpretation...??

I follow your reasoning about Barbour. But didn't he miss one very important factor? Doesn't Barbour also have to double the speed of light, for example, if the distance between Earth and Moon has doubled, and you want the same result as yesterday?? Or, Barbour has to decrease the speed of our atomic clocks to half?? But that's maybe comes automatically? From the increased (doubled? quadrupled?) gravitation of a doubled-sized Earth... (even if it seems like a too big 'effect' for a layman...)

And further more. Doesn't Barbour have to redesign ALL of the four fundamental interactions of nature, In the Standard Model of particle physics, the strong and weak nuclear force etc? If the all distances in the atom also get doubled??

A practical example: If our Sun would double in size overnight, and Barbour doesn't adjust the laws of physics accordingly, we would know something strange had happened last night! The Sun 2.0 would burn its fuel much faster, and hence would die much quicker. And the end of the Sun 2.0 would be a whole different enchilada, than the end of Sun 1.0!!

Please, tell me I'm right on this one? I suddenly feel a clear mind!

Dmitry67

Copenhagen interpretation <> Many-worlds interpretation
Copenhagen interpretation (together with the 'collapse') is almost abandoned in 21th century. So forget about the 'collapse'

DevilsAvocado

Okay Dmitry67, thanks! I'm working on your other replays. I'll be back.

Gan_HOPE326

No, that's the point. Doubling distances means doubling everything: light speed is 3e8 meters per second, but in such a 2.0 universe, the very concept of "meter" would be doubled. It's not about enlarging objects: it's about stretching the fabric of space itself. That's why he says that nothing changes: or better, you could say it's even meaningless to think such a concept, because, how can you tell Universe 2.0 is twice the size of Universe 1.0 if you don't have anything external to the universe to measure it?

P.S. if we're talking about doubling linear distances, anyway, volumes, and then, roughly, masses, would be multiplied per 8. Yet still, since gravity goes as mass/square of radius, a "double radius" Earth, provided it had the same density than ours, would have a doubled gravitational force. And here's the trick: in Barbour's hypotesis, Planck constant, dielectric constant, Newton's gravitational constant etc. would change as well; as a result, we'd have an Earth made of bigger (less dense) atoms, with different laws, etc., so that its gravity wouldn't change from the original value.

DevilsAvocado

Okay Houston, I Read You Loud and Clear!

But as "Cranky Layman" I still argue that Barbour maybe should express his hypothesis in this way:

"If all distances, scales and (physical) constants in the universe were doubled over night - nothing would tell us this had happened."

This I will have for breakfast tomorrow!
(i.e. if the QM-guys do high-five as wel)

With all the respect for Barbour (and your interest in his theory), it does make me 'nervous' when he tries to visualize Eternity with this "thing" (that looks like a drying rack to me)...

http://www.youtube.com/watch?v=WKsNraFxPwk


(Says the man who 'believes' Extra-Universal Space!! )

DevilsAvocado

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1) I love Max Tegmark , he is a brave man and the Grand Master of Mind-Blowing Theories!

• TOE - Theory of Everything
• ERH - External Reality Hypothesis
• MUH - Mathematical Universe Hypothesis
• CUH - Computable Universe Hypothesis

Tegmark probably has more intelligence in his left pinky TOE than I have in my whole brain, and obviously I cannot comprehend all of his Mathematic Universe Hypotesis.

But then again, I am the DevilsAvocado and I did complete my course at the Argument Clinic , and therefore I naturally gonna have objections about this.

"If a future physics textbook contains the TOE, then its equations are the complete description of the mathematical structure that is the external physical reality. We write is rather than corresponds to here, because if two structures are isomorphic, then there is no meaningful sense in which they are not one and the same."

Huum, isn't this 'maneuver' a little bit too easy to 'replace' the physical reality with math? Isomorphic is mainly a mathematical 'tool' (right?) for mapping between objects... isn't that 'cheating'?

Example: If you have a complete technical drawing of a house, and make a complementation with all scientific knowledge about the material, down to quarks - then Tegmark could call the technical drawing and the physical building isomorphic, right? But can Tegmark take his family and move in to that Technical Drawing?? I say no.

"Wigner argued that 'the enormous usefulness of mathematics in the natural sciences is something bordering on the mysterious', and that 'there is no rational explanation for it'."

I DO admire all people who use extremely advanced mathematics to investigate and explore the world. They are my heroes!

At the same time, I think there is a little risk of losing perspective and getting 'lost in translation', and fall in love with the 'pure magic' of the tools you are working intensely with. For me, as layman, it feels extremely awkward that the physical world doesn't really exist - it's just equations...

In Erwin Schrödinger's book - What Is Life - from 1944 (old stuff I know! ) he wrote as a section header in Chapter 1:

PHYSICAL LAWS REST ON ATOMIC STATISTICS AND ARE THEREFORE ONLY APPROXIMATE

And if I'm not wrong; there is NOT today ANY mathematical equation that can describe what really goes on in the QM-world. All we calculate are probabilities, right? And Heisenberg's uncertainty principle doesn't give us much hope of ever getting rid of this 'trauma', right? So, how can (mathematic) approximations ever be the real physical world we live in??

Another side of this coin could be the EPR paradox, and the fact that Alain Aspect 1982 (almost?) performed a validation of Bell's theorem (Bell inequality). The world is random by nature. As far as I know, mathematics is NOT random by nature?

Tegmark's solution to banish randomness:
" ... so that the final state is a superposition of observers obtaining all outcomes, then in the limit of infinitely many bits, almost all observers will find their bit strings to appear perfectly random and conclude that the conventional quantum probability rules hold."

Huum, "a superposition of observers obtaining all outcomes" = Many-worlds interpretation ...??

If so, I not like...

The final objection is completely homemade, and feel free to laugh out loud!
What's the most natural geometric shape in the universe? Yes, circles/spheres. Not quadrates/triangles. What is the natural mathematic tool for handling circles and spheres?

3.14159265358979323846264338327950288 ... ... ... ... ... ... ... ...

Just a layman 'feeling' - but shouldn't ∏ be more 'exact/natural', if the Mathematical Universe Hypothesis is correct...??


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2) Is the reason for NOT running into infinities even for the infinite Universe, the fact that we can never get out of our local light-cone (event-horizon)? Or is this 'embedded' more 'fundamentally' in GR?


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3) "b) is compatible with the observations"... Hehe, this is the Holy Grail of avoiding difficult questions! Business as usual, everything (observable) works, without any help of the turtles!

DevilsAvocado

Turtles all the way down
I think I've found the solution... The last turtle is not that big, and he has all the information at the fingertip!

DevilsAvocado

Okay, thanks for info.

And how do we relate Qunatum Decoherence to Tegmark's:
"a superposition of observers obtaining all outcomes"

To me it sounds like every observer is gonna have their own bit...??

Dmitry67

DevilsAdvocado, regarding your objections, how do you know if you are living in the virtual reality or real reality? "complete technical drawing of a house" is not a good example for "virtual reality". So you cant live there.

The second part of your objections are rather constatation of fact that we don't know the 'Ultimate', TOE equations. Yes, this is true. But we hope we'll learn them soon.

And precise and deterministic laws of physics can lead to the appearence of randomness (MWI, BM)

Dmitry67

It depends on how you define the "observer"
After the schoedinger cat experiment:

You + closed box with 1/2 dead cat + 1/2 alive cat

So you can never see the superposition of cats
you get decoherenced with the box literally after you exchange few photons, and the system evolves into

1/2 Happy you observing alive cat + 1/2 Sad you observing dead cat

DevilsAvocado

Thanks. Virtual reality is cool, and could be one explanation for the "turtle problem". Can we be absolutely sure about the vastness of our universe in that case? I mean, is there any way to tell for sure (CMB, etc)?

TOE is very thrilling. I can't wait.

A deterministic law of physics sounds a little 'disturbing'. I like my free will...

DevilsAvocado

Yes, but then again Tegmark's MUH has a problem to banish the randomness in the Geiger counter?
Or, Curiosity Killed The Cat??

Dmitry67

In MWI free will is compatible with determinism.

Virtual reality is cool, but this is not what Max meant. The idea of Matrix is too popular, but what he is saying is much deeper.

Let me ask you - how you can tell the mathematical system from a physical one?

Dmitry67

MUH is unrelated to Schroedinger cat problem
MWI is.
Randomness is an illusion.
Both branches (deterministically) exist
Observer is each branch thinks that the outcome was random.

DevilsAvocado

Well, I guess if we accept the possibility that we and the universe are a running simulation, then the mathematical system setting the rules, must be more real than the actual simulation!?

And I guess there is NO way to find out if we are real real, or simulated real, i.e. if the 'programmer' did his job.

If this is true; how can we ever find TOE?? The 'programmer' must be an idiot if he programmed his own 'weakness'?

If we are not simulated, then I say my Technical Drawing is a pretty good indicator.

Another (old) question that pops up in my head; Nick Bostrom is almost sure we are in a simulated reality, and that it's impossible to tell the difference between real reality and simulated reality.

Hence the (mathematical) simulation system/rules/programming must be 'govern' from outside the simulation, right? How can the 'simulation governors' (and here goes my turtles again! ) be absolutely sure they are not simulated as well?? And so on, and so forth, in all eternity... (And, does this make any 'real' difference...??)


Finally a new nut for you to crack:
If we are in a simulated reality - how you can tell a 'real' mathematical system that works, from a simulated mathematical system that is simulated to work?

DevilsAvocado

So "observer in each branch" is not the same as splitting observer worlds?

(I must be stupid )

Dmitry67

You're right, there is NO way to find out if we are PEFFECTLY simpulated. Then it is IRRELEVANT if we are simulated or not.And MAx suggests not to talk about the simulation.

For the same reason there is no difference between physical and mathematical - beings in the mathematical structure feel it perfectly physical and real.