virtual particles and dark energy

[jillery]

The following is a link to a 9-minute Veritasium video which does two
things:

1. Explains how virtual particles are the source of dark energy.
2. Explains how virtual particles can't be the source of dark energy.

<https://www.youtube.com/watch?v=g20JZ2HNZaw>

Short version: If the acceleration of the universe is caused by dark
energy, then the *measured* value of dark energy would be 10^-8 ergs
per cubic centimeter (that's a fraction, of eight zeroes to the right
of the decimal point). But if virtual particles are the cause of dark
energy, then the *calculated* value would be 10^112 ergs per cubic
centimeter (that's 112 zeros to the left of the decimal point). This
difference of 10^120 is called ""the worst theoretical prediction in
the history of physics" aka the Cosmological Constant problem.
Parenthetically and AIUI this is the source of the number that
Creationists use for a fine-tuning PRATT.

Also, Brian Schmidt makes without explanation a statement I had not
heard before:
***************************
@00:41
We always think that gravity always pulls. But according to Einstein,
the way gravity works really depends on the material itself. And
energy tied to space, gravity pushes, it doesn't pull.
***************************

I understand how a region of space devoid of matter would act as if
the void were pushing matter away, when in fact the matter would
really be being pulled toward the relatively greater density of matter
surrounding the void. But that's an entirely different thing from
what Schmidt mentions.

Also, if in fact the vacuum energy of spacetime is the cause of cosmic
Expansion, then ISTM vacuum energy can not be the cause of cosmic
Inflation, which is hypothesized to have happened in the first 10^-35
seconds, as there would have been no vacuum within the universe to
provide such energy.

--
You're entitled to your own opinions.
You're not entitled to your own facts.

[erik simpson]

As I am ill-equipped to understand in any quantitative way the current ideas
about the "cause" of inflation or the current acceleration, my opinion isn't worth
much, but I have a gut feeling we're not looking in the right places or with the right
tools. String theory keeps rearing it head, and at least so far it has been a pretty
sterile theory. If the answer is to be found in vacuum fluctuations, something must
be averaging out or masking these effect.

[jillery]

>As I am ill-equipped to understand in any quantitative way the current ideas
>about the "cause" of inflation or the current acceleration, my opinion isn't worth
>much, but I have a gut feeling we're not looking in the right places or with the right
>tools. String theory keeps rearing it head, and at least so far it has been a pretty
>sterile theory. If the answer is to be found in vacuum fluctuations, something must
>be averaging out or masking these effect.

Don't give up just because you can't do string theory. That's way
above most people's paygrade. AFAIC I do well enough to understand
these ideas qualitatively.

For instance, a fundamental principle of QM is Heisenberg's
Uncertainty Principle, which says certain properties can't be known
with certainty at the same time, ex. position and momentum. If that
is true, then there can't be any point in spacetime where there is
literally nothing, else that point's position and momentum would be
precisely zero, a violation. That's also why absolute zero can't be
reached.

The effects of virtual particles have been measured, even though they
can't be observed. But just because they exist, and they are a
phenomenon of vacuum, and they manifest as a force, does not mean they
are the cause of cosmic Expansion. So what is the cause? I don't
know. But then, neither does anybody else.

[erik simpson]

Heisenberg's principle is somewhat analogous to the 2nd law of thermodynamics:
they're both simply stated and arise naturally in the mathematical formulations,
and they're both regularly misapplied and misunderstood. I had a lot of thermo and
statistical mechanics in my past, and a fair but lesser aquaintance with QM. I've forgotten
lots, but even when I knew more (or at least thought I did) I'd never pontificate on QM.
Correlations and entanglement can lead to very unintuitive and surprising results. At this
point I'm strictly an interested spectator.

[jillery]

On Sun, 14 Mar 2021 17:03:32 -0700 (PDT), erik simpson

I agree. It's enough for me to repeat those who are qualified to
pontificate.