Inflationary vs deflationary phase of Big Bang

In summary, the inflationary phase of the Big Bang refers to a rapid expansion of the universe that occurred within the first fractions of a second, leading to a uniform and isotropic cosmos. This phase explains the observed large-scale structure of the universe and the uniformity of the cosmic microwave background radiation. In contrast, the deflationary phase follows this rapid expansion, characterized by a slower, more gradual expansion of the universe. During this phase, the dynamics of cosmic expansion are influenced by various forms of energy and matter, leading to the diversity of structures seen in the universe today. Both phases are crucial in understanding the evolution of the universe from its initial singularity to its current state.
  • #1
BIGphysician
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TL;DR Summary
Shape of the big bang? And universe?
Hi I'm a medical doctor, this is just a hobby my uncle got me interested in as a kid. If the universe is acceleration and galaxies are moving further apart, we assume the universe as a whole is expanding as a result. It's also projected to my understanding that eventually the universe will contact and a cycle of matter and force creation will be recycled four the next big bang.

How do we know that we aren't accelerating towards a singular contraction point rather than away from one (deflating vs inflating). Every galaxy is moving away from every other at the same rate and distance?

What's the shape of the universe? If it's an expanding sphere with a centrally located origin of force, galaxies originating from different relative locations at the singularity would result in different relative distances?
 
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  • #2
Is that what your uncle told you?
 
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Welcome to PF, doctor. :smile:

Have a look at some of the PF Insights articles about the Big Bang and related issues, to see if they help with your understanding:

https://www.physicsforums.com/insights/?s=big+bang
 
  • #4
PeroK said:
Is that what your uncle told you?
Something like that, he wrote a several thousand page primer on quantum mechanics but it's over my head, what's your view of the meta physics
 
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BIGphysician said:
If the universe is acceleration and galaxies are moving further apart, we assume the universe as a whole is expanding as a result.
No, we don't assume - we can see distant galaxies moving away in all directions. It's also a fairly straightforward implication of feeding the cosmological principle into Einstein's Field Equations.
BIGphysician said:
It's also projected to my understanding that eventually the universe will contact
Assuming you mean "contract" here, maybe. Our best estimates don't rule out an eternally expanding universe.
BIGphysician said:
and a cycle of matter and force creation will be recycled four the next big bang.
That's highly speculative. Penrose thinks so, but it's not anywhere near a fully fleshed out theory, let alone generally accepted.
BIGphysician said:
How do we know that we aren't accelerating towards a singular contraction point rather than away from one (deflating vs inflating).
I don't even know how that would make sense.
BIGphysician said:
Every galaxy is moving away from every other at the same rate and distance?
No. For any pair of galacies a given distance apart they are moving further apart at the same rate (more or less, excluding gravitationally bound ones). That does not mean all galaxies are moving apart at the same rate.
BIGphysician said:
What's the shape of the universe?
Infinite in extent, would be our best guess. Even in the case of a closed universe, though, there is no center.
 
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BIGphysician said:
what's your view of the meta physics
This is a forum about physics, not metaphysics.
 
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BIGphysician said:
what's your view of the meta physics
Probably not too different than your view of "metamedicine".
 
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BIGphysician said:
If the universe is acceleration and galaxies are moving further apart, we assume the universe as a whole is expanding as a result.
Assuming you mean accelerating and not acceleration (which in your sentence would not make sense) then you have it backwards. The universe is expanding due to something we do not understand the cause of. We call it "dark energy" and BECAUSE of dark energy, the galaxies that are not locally bound are moving away from each other.

If two galaxies are a billion light years apart and are receding from each other at, say X miles per hour, then two galaxies that are two billion light years apart are receding from each other at 2X. Expansion is a rate based on distance, not a set speed.
 
  • #9
phinds said:
The universe is expanding due to something we do not understand the cause of. We call it "dark energy" and BECAUSE of dark energy, the galaxies that are not locally bound are moving away from each other.
Are you talking about expansion or accelerating expansion?
 
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Jaime Rudas said:
Are you talking about expansion or accelerating expansion?
Good catch. Thank you.

Obviously I was talking about, and should have SAID I was talking about, the acceleration of expansion.

@BIGphysician the current expansion of the universe is a result of the ORIGINAL expansion of the universe. Dark energy has cause that expansion to accelerate. It was believed until fairly recently that the expansion of the universe would either slow down and reach a steady state or even reverse and collapse backwards.

It was discovered in the first actual evidence either way that, much to scientists surprise, the universe's expansion was accelerating. This was so unexpected that the data was at first suspected, but found to be correct.

1713064478780.png
 
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FAQ: Inflationary vs deflationary phase of Big Bang

What is the inflationary phase of the Big Bang?

The inflationary phase of the Big Bang refers to a rapid exponential expansion of the universe that is believed to have occurred within the first few moments (approximately 10^-36 to 10^-32 seconds) after the Big Bang. This period of inflation is thought to have caused the universe to expand faster than the speed of light, smoothing out any irregularities and leading to the large-scale structure we observe today.

What is the deflationary phase of the Big Bang?

The deflationary phase is not a commonly used term in cosmology, but it can refer to the subsequent cooling and expansion of the universe after the inflationary phase. During this phase, the universe continues to expand, but at a decelerating rate as it cools down, leading to the formation of subatomic particles, atoms, and eventually stars and galaxies.

How does inflation solve the horizon problem?

The horizon problem arises from the observation that distant regions of the universe have nearly the same temperature and density, despite being too far apart to have ever been in causal contact. The inflationary phase provides a solution by proposing that these regions were once close together before being rapidly inflated, allowing them to equilibrate before being pushed far apart. This explains the uniformity of the cosmic microwave background radiation.

What evidence supports the inflationary model?

Several lines of evidence support the inflationary model, including the uniformity of the cosmic microwave background radiation, the large-scale structure of the universe, and the specific patterns of temperature fluctuations observed in the CMB. Additionally, inflation predicts the existence of gravitational waves, which could be detected by future experiments, providing further support for the theory.

What are the implications of inflation for the fate of the universe?

The implications of inflation for the fate of the universe are profound. If inflation occurred, it suggests that the universe is flat and will continue to expand indefinitely. This leads to the possibility of a "big freeze," where the universe gradually cools and darkens as stars burn out and galaxies drift apart, rather than collapsing back in on itself or reaching a steady state.

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