<p>I have been reading about <a href="https://en.wikipedia.org/wiki/Inflation_(cosmology)" rel="nofollow noreferrer">cosmic inflation</a>: the initial step in the formation of our universe when space/time inflated to fill whatever preceded it.  I understand that this inflation happened faster than the speed of light, but did not violate any laws because it is space/time itself inflating not some object in motion.</p>
<p>I have read that this primordial cosmic inflation can be explained by false vacuum decay.   The preceding false vacuum decays into a lower energy state of true vacuum.
<a href="https://arxiv.org/abs/1404.1207" rel="nofollow noreferrer">Spontaneous creation of the universe from nothing</a>.</p>
<blockquote>
<p>In summary, we have presented a mathematical proof that the universe
can be created spontaneously from nothing. When a small true vacuum
bubble is created by quantum fluctuations of the metastable false
vacuum, it can expand exponentially if the ordering factor takes the
value p = −2 (or 4). In this way, the early universe appears
irreversibly.</p>
</blockquote>
<p>There is a premise that the current state of the universe is still not at the lowest vacuum energy and our universe could undergo <a href="https://en.wikipedia.org/wiki/False_vacuum_decay" rel="nofollow noreferrer">false vacuum decay</a>, with our vacuum decaying down to some yet lower energy state of true vacuum.  The resulting new vacuum state would bring with it new regimens of physical laws and everything else.  But in discussions of false vacuum decay, the expanding bubble of true vacuum is said to expand at the speed of light.</p>
<p>The question: <strong>why would a second episode of false vacuum decay occur at the speed of light if the first one (the cosmic inflation) did not?</strong></p>

CC BY-SA 4.0
2021-12-05T17:11:30.377Z
Perhaps this is better suited for Physics SE?
Daddy Kropotkin
CC BY-SA 4.0
2021-12-05T18:12:00.060Z
@DaddyKropotkin - I considered that.  But then I saw there was a cosmological inflation tag on this stack and I considered that an invitation!
Willk
CC BY-SA 4.0
2021-12-05T19:55:07.650Z
I suppose vacuum bubbles propagate through space, which is only possible at or below the speed of light. In contrast, inflation (and ordinary universe expansion, for that matter) is not something that moves through space; rather it is space itself expanding, which it can do as fast as it wants to.
pela
<cosmological-inflation><vacuum>
Cosmic inflation was faster than light. Why would a false vacuum decay bubble only expand at the speed of light?
Willk
# Cosmic inflation was faster than light. Why would a false vacuum decay bubble only expand at the speed of light?

(Asked by: username_0 on 2021-12-05)

I have been reading about [cosmic inflation](https://en.wikipedia.org/wiki/Inflation_(cosmology)): the initial step in the formation of our universe when space/time inflated to fill whatever preceded it. I understand that this inflation happened faster than the speed of light, but did not violate any laws because it is space/time itself inflating not some object in motion.

I have read that this primordial cosmic inflation can be explained by false vacuum decay. The preceding false vacuum decays into a lower energy state of true vacuum.
[Spontaneous creation of the universe from nothing](https://arxiv.org/abs/1404.1207).

> In summary, we have presented a mathematical proof that the universe
> can be created spontaneously from nothing. When a small true vacuum
> bubble is created by quantum fluctuations of the metastable false
> vacuum, it can expand exponentially if the ordering factor takes the
> value p = −2 (or 4). In this way, the early universe appears
> irreversibly.

There is a premise that the current state of the universe is still not at the lowest vacuum energy and our universe could undergo [false vacuum decay](https://en.wikipedia.org/wiki/False_vacuum_decay), with our vacuum decaying down to some yet lower energy state of true vacuum. The resulting new vacuum state would bring with it new regimens of physical laws and everything else. But in discussions of false vacuum decay, the expanding bubble of true vacuum is said to expand at the speed of light.

The question: **why would a second episode of false vacuum decay occur at the speed of light if the first one (the cosmic inflation) did not?**

**Tags:** cosmological-inflation, vacuum

> **Comments:**
> **username_1**: Perhaps this is better suited for Physics SE?  
> **username_0**: @DaddyKropotkin - I considered that.  But then I saw there was a cosmological inflation tag on this stack and I considered that an invitation!  
> **username_2**: I suppose vacuum bubbles propagate through space, which is only possible at or below the speed of light. In contrast, inflation (and ordinary universe expansion, for that matter) is not something that moves through space; rather it is space itself expanding, which it can do as fast as it wants to.  

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## 0 answers

