Cosmological constant estimation in QFT

In summary, the conversation discusses the interpretation of a large estimated value in quantum mechanics and whether it should be approached as a measurement result or an ontological property. It is mentioned that the predicted value is off by 120 orders of magnitude, indicating that some assumptions may be incorrect. Additionally, the concept of vacuum energy in QFT is defined as arbitrary except in general relativity, where it can be measured. However, attempts to reconcile this value in QFT have been unsuccessful.
  • #1
ueit
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My question is about the interpretation of the large estimated value. In QM we are supposed to think in terms of measurement results and not of ontological properties. So, if QFT predicts a large vacuum energy what is the correct approach?

1. The predicted value is the result you get if you measure the vacuum energy.
2. The predicted value is an intrinsic property of the vacuum and should therefore gravitate.

Thanks,

Andrei
 
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  • #2
Well, the predictions are off by 120 orders of magnitude, which means some assumptions are incorrect. The QFT vacuum energy isn't something that is measured, but just defined. The zero point of energy is completely arbitrary in every field of physics except for general relativity. So you could use GR to define the "measured" vacuum energy, and try to look for ways to get that value in QFT. So far, unsuccessful.
 

1. What is the cosmological constant in QFT?

The cosmological constant, also known as Lambda, is a term in Einstein's field equations of general relativity that represents the energy density of the vacuum of space. In Quantum Field Theory (QFT), it is a constant parameter that appears in the equations of motion for fields and affects the curvature of space-time.

2. How is the cosmological constant estimated in QFT?

The cosmological constant is estimated in QFT by calculating the vacuum energy density of the universe, which is related to the cosmological constant through the Einstein field equations. This calculation involves summing up the contributions of all the fields in the universe and taking into account the effects of quantum fluctuations.

3. Why is the cosmological constant important in QFT?

The cosmological constant is important in QFT because it is believed to be responsible for the accelerated expansion of the universe. It also plays a crucial role in models of particle physics and can affect the formation of structures in the early universe.

4. How does the cosmological constant affect the universe?

The cosmological constant affects the universe by influencing the expansion rate of space-time. A positive cosmological constant leads to an accelerated expansion, while a negative cosmological constant would result in a decelerated expansion. The value of the cosmological constant also affects the overall geometry of the universe.

5. Can the cosmological constant be measured in QFT?

Currently, there is no direct measurement of the cosmological constant in QFT. However, its effects can be indirectly observed through the accelerated expansion of the universe and the structure formation in the early universe. The exact value of the cosmological constant is still a subject of ongoing research and debate in the scientific community.

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