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Neuron

What determined the inital state of the universe?

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Hi everyone,

Reading other threads in this forum, like https://www.scienceforums.net/topic/120772-please-tell-me-we-have-free-will/, it seems to be well-accepted that our universe is almost completely (except for quantum uncertainty) deterministic.

My question is, what determined the inital state of the universe? I mean, where did all the initial information come from?

Thank you for reading.

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10 minutes ago, Neuron said:

My question is, what determined the inital state of the universe?

This is unknown, currently. All we know is that it was once in a uniformly hot, dense state and then it expanded and cooled. How it got to be in that state is unknown. One of the challenges is how it came to be so homogeneous. Inflation is one hypothesis. But if the universe is cyclic (the "big bounce" model) then that could explain it too. On the other hand, some attempt to add quantum theory to the equation suggest that the universe could be infinitely old, which would also allow it to become homogeneous.

More evidence, and probably better theories, are needed to give us any chance of knowing.

 

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And your question provides the answer...

30 minutes ago, Neuron said:

our universe is almost completely (except for quantum uncertainty) deterministic

That pesky quantum uncertainty at the scales of the Planck era, toss determinism out the window.
( until we can force Quantum theory and GR to 'play nice' )

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Posted (edited)
16 minutes ago, MigL said:

And your question provides the answer...

That pesky quantum uncertainty at the scales of the Planck era, toss determinism out the window.
( until we can force Quantum theory and GR to 'play nice' )

Can we not get them to "play nice" without determinism?

(If there's a free will...there's a way...;))

Edited by J.C.MacSwell

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42 minutes ago, J.C.MacSwell said:

Can we not get them to "play nice" without determinism?

(If there's a free will...there's a way...;))

Er... that invokes a god.  :)

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1 hour ago, StringJunky said:

Er... that invokes a god.  :)

Are you saying that free will requires a god? That determinism is the only other option?

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2 hours ago, J.C.MacSwell said:

Can we not get them to "play nice" without determinism?

Don't know if determinism will survive Quantum Gravity.
But currently Quantum theory and GR are kicking and screaming trying to avoid unification.

As Batman said...

"My parents taught me a different lesson, dying in the gutter for no reason at all... They taught me the world only makes sense if you force it to.”

What...  I'm not gonna believe Batman ?

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56 minutes ago, MigL said:

Go ahead; Make my day lasagna.

Clint Eastwood  Garfield

Odie was here

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6 hours ago, QuantumT said:

Are you saying that free will requires a god? That determinism is the only other option?

Freewill at the initial state of the universe? That implies a conscious mind.

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12 hours ago, Strange said:

This is unknown, currently. All we know is that it was once in a uniformly hot, dense state and then it expanded and cooled. How it got to be in that state is unknown. One of the challenges is how it came to be so homogeneous. Inflation is one hypothesis. But if the universe is cyclic (the "big bounce" model) then that could explain it too. On the other hand, some attempt to add quantum theory to the equation suggest that the universe could be infinitely old, which would also allow it to become homogeneous.

That's interesting, thank you

12 hours ago, MigL said:

That pesky quantum uncertainty at the scales of the Planck era, toss determinism out the window.
( until we can force Quantum theory and GR to 'play nice' )

Wow, I never thought about this. Is this mathematical demonstrated/demonstrable?

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Posted (edited)
39 minutes ago, Neuron said:

That's interesting, thank you

Wow, I never thought about this. Is this mathematical demonstrated/demonstrable?

General Relativity describes cosmological scales to high precision but as you get to denser states and smaller sizes it loses accuracy and by the time you get to the most dense state it falls apart. This is where Quantum physics comes in but, as yet, there is no quantum model of gravity, so, scientists are stuck with two models for different aspects of the universe; the very large and the very small. Nether of these models are applicable in both aspects, just the one.

Edited by StringJunky

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Posted (edited)
2 hours ago, Strange said:
Quote

With no particles or antiparticles, no matter or radiation, no identifiable quanta of any type in your Universe, all you'd have left is the void of empty space itself. To some, that's the true scientific definition of "nothingness."
But certain physical entities still remain, even under that highly restrictive and imaginative scenario. The laws of physics are still there, which means that quantum fields still permeate the Universe. That includes the electromagnetic field, the gravitational field, the Higgs field, and the fields arising from the nuclear forces. Spacetime is still there, governed by General Relativity. The fundamental constants are all still in place, all with the same values we observe them to have.

That begs the question:

14 hours ago, Neuron said:

 I mean, where did all the initial information come from?

 

Edited by Kartazion

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31 minutes ago, Kartazion said:

That begs the question:

14 hours ago, Neuron said:

 I mean, where did all the initial information come from?

 

I don't think that is a question science can answer. It belongs in the realm of philosophy (or religion, if you prefer).

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I was more interested in what happened after the big bang rather than before (if there was a "before")

On 4/30/2020 at 11:20 PM, Strange said:

All we know is that it was once in a uniformly hot, dense state and then it expanded and cooled

Why is not homogeneous anymore? How did the expansion perturbate that state?

MigL hypothesis looks plausible but I understand a better theory is needed before being sure.

22 hours ago, Strange said:

I don't think that is a question science can answer. It belongs in the realm of philosophy (or religion, if you prefer)

I think a unified theory will provide an answer.

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Posted (edited)
9 hours ago, Neuron said:

I was more interested in what happened after the big bang rather than before (if there was a "before")

Why is not homogeneous anymore? How did the expansion perturbate that state?

MigL hypothesis looks plausible but I understand a better theory is needed before being sure.

I think a unified theory will provide an answer.

As the density eases with inflation, irregularities in the density distribution become more likely and thus increasing  inhomogeneity results because the slight differences in gravity will cause material to clump irregularly towards the areas with higher mass-energy.

E2A

Edited by StringJunky

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If you 'reverse' time and approach t=0, at the Planck era t = 10^-43 sec, Some of our physical laws, such as GR, cease making meaningful predictions; Some others don't.
Quantum Mechanics, and all its effects, still work to some degree.
Even the isotropic, homogenous, hot, dense state, that was present when the Big Bang began, was subject to the Heisenberg Uncertainty Principle. And anything subject to the HUP, by necessity, experiences quantum fluctuations.
These quantum fluctuations would have experienced exponential inflation ( possibly ), and expansion,  since that era.
And they would have 'seeded' the large scale structures of the present day universe.
( which is still isotropic and homogenous on large enough scales )

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Does anyone think that the initial conditions of big were were a net zero energy event, \Delta U(gravitational potential) + Energy (big bang) = 0.

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6 hours ago, Wulphstein said:

Does anyone think that the initial conditions of big were were a net zero energy event, \Delta U(gravitational potential) + Energy (big bang) = 0.

Some people do: https://en.wikipedia.org/wiki/Zero-energy_universe 

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