# Has a calculation of the vacuum energy density been done with strings?

• A
• JandeWandelaar
In summary, the conversation discussed the discrepancy between the calculated vacuum energy density and reality, with an estimated mass equivalent of $10^{96}$ kilograms. The possibility that the point-like structure of particles could be the cause of this discrepancy was also mentioned. It was noted that string theory, which does not assume a point-like structure, may provide a more accurate estimate. However, there is currently no calculation of the vacuum energy density in string theory. The conversation also touched on the usage of LaTeX on the forum and the difficulty in finding an estimate in string theory. It was acknowledged that the discrepancy calculation is a heuristic and that there are published papers on calculating vacuum energy in various QFTs. Personal speculation and incorrect statements as facts were discouraged.
JandeWandelaar
TL;DR Summary
The vacuum energy density of the vacuum, as calculated in standard QFT, shows a discrepancy of about $10^{120}$ with what we see. Has the value been calculated in string theory, which doesn't assume point-like particles?
The calculation of the vacuum energy density gives us a discrepancy with reality. There should be a mass equivalent of about $10^{96}$ kilograms. I'm wondering if the assumed point-like "structure" of particles could be the cause of this wrong value.

Since string theory doesn't assume a point-like structure, I asked myself if a calculation of the energy density with strings has been done.

Delta2
JandeWandelaar said:
The calculation of the vacuum energy density gives us a discrepancy with reality.

Nonsense. There is no such calculation. At best, there is an estimate, and not a very good one at that.

Starting threads by presenting incorrect statements as facts is, in general, not a good plan.

Why does the estimate differ so much with what we see? Is there an estimate in string theory? I could not find it. Only estimates in standard QFT.

Delta2
Nonsense. There is no such calculation. At best, there is an estimate, and not a very good one at that.

Starting threads by presenting incorrect statements as facts is, in general, not a good plan.
BTW, do you know why the LaTex doesn't function? Is $10^{120}$ not right?

JandeWandelaar said:
BTW, do you know why the LaTex doesn't function? Is $10^{120}$ not right?
you got to put double $at start and end. And then refresh the page. JandeWandelaar JandeWandelaar said: BTW, do you know why the LaTex doesn't function? Is$10^{120}\$ not right?

for LaTeX on the forum: https://www.physicsforums.com/help/latexhelp/

This is a summary of how the ##10^{120}## discrepancy calculation is done, it is a bit heuristic
Calculating vacuum energy in various QFTs is a thing, there are several papers published on that matter. Here is one such article https://arxiv.org/abs/1302.5934

JandeWandelaar and Delta2
Thanks dude (am I allowed...?).

Delta2
Is this about the so called, ground state energy of the fields?

JandeWandelaar said:
Why does the estimate differ so much with what we see?
Nobody knows. This is an open area of research.

JandeWandelaar said:
Is there an estimate in string theory? I could not find it.
I'm not aware of one either.

PeterDonis said:
Nobody knows. This is an open area of research.I'm not aware of one either.
Somehow I think $$10^{120}$$ and the cube of the Planck length, $$10^{-115}$$, are related.

malawi_glenn, PeroK and Motore
JandeWandelaar said:
Somehow I think $$10^{120}$$ and the cube of the Planck length, $$10^{-115}$$, are related.
Personal speculation of this kind is off limits here.

JandeWandelaar

## 1. What is vacuum energy density?

Vacuum energy density refers to the energy that exists in a vacuum, or empty space. Even though a vacuum may appear to be completely empty, according to quantum field theory, it is actually filled with particles that constantly pop in and out of existence, creating a fluctuating energy field.

## 2. How is vacuum energy density calculated?

The calculation of vacuum energy density involves using mathematical equations from quantum field theory to determine the expected energy of the vacuum. This calculation can be done using different theoretical frameworks, such as string theory.

## 3. What is string theory?

String theory is a theoretical framework that attempts to explain the fundamental nature of matter and energy in the universe. It proposes that the smallest building blocks of the universe are not particles, but tiny strings that vibrate at different frequencies, giving rise to the different particles and forces we observe.

## 4. Has a calculation of the vacuum energy density been done with strings?

Yes, there have been attempts to calculate the vacuum energy density using string theory. However, due to the complexity of the theory and the lack of experimental evidence, the results are still highly debated and not universally accepted.

## 5. What are the implications of a calculation of the vacuum energy density with strings?

If a calculation of the vacuum energy density using string theory is successful and widely accepted, it could provide a deeper understanding of the fundamental nature of the universe and potentially lead to new discoveries in physics. It could also have implications for other areas of science, such as cosmology and astrophysics.

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