Most people have a very negative view of the existence of negative mass. When negative numbers first appeared in this world, there were many people who could not accept it. It seems that negative mass is such a state for some people.
However, times change, and sometimes objects that seemed impossible to exist come into existence. The universe is currently expanding at an accelerating rate, and since gravity is the dominant force on a cosmic scale, a repulsive force or anti-gravity is needed for the universe to expand at an accelerating rate, which is a phenomenon that can be explained by the existence of negative mass.
The current standard cosmology is the ΛCDM model. This model explains the dark energy problem by introducing a entity that has positive energy density and exerts negative pressure.
However, cracks in this ΛCDM model have been increasing recently, and accordingly, the time is approaching when other possibilities and interpretations should be seriously examined.
The ΛCDM model consists of Λ(Lambda) and CDM(Cold Dark Matter), but it has not succeeded in explaining the source of Λ, which is the core, and the vacuum energy, which was a strong candidate, has an unprecedented error of 10^120 between the theoretical value and the observed value.
CDM has also not been discovered despite continued experiments. In addition, particle accelerator experiments, which are a completely different approach from WIMP detectors, have not found a candidate for CDM.
Furthermore, the existence of the Hubble tension problem has recently become clear, and in January 2024, the DES (Dark Energy Survey) team raised the possibility that the cosmological constant model may be wrong, and in April 2024, the DESI (Dark Energy Spectroscopic Instrument) team announced results suggesting that the cosmological constant model may be wrong. Since it is only the first year of results, we will have to wait a little longer for the final results.
1)Dark Energy Survey team
https://noirlab.edu/public/news/noirlab2401/?lang
2)Dark Energy Spectroscopic Instrument team
https://arstechnica.com/science/2024/04/dark-energy-might-not-be-constant-after-all/#gsc.tab=0
Through the acceleration equation, we know that the universe is expanding at an accelerating rate.
In the acceleration equation, (c=1)
(1/R)(d^2R/dt^2) = -(4πG/3)(ρ+3P)
In order for the universe to accelerate, the right side must be positive, and therefore, (ρ+3P) must be negative. Here ρ is the mass density, so for the universe to expand acceleratingly, (ρ+3P)<0, and by dimensional analysis, this requires a negative mass density.
This is a phenomenon that can be explained if there is a negative mass density or negative pressure. Currently, the mainstream explains the accelerated expansion of the universe by assuming an entity with negative pressure.
However, we still do not know what the source of dark energy is. So, the cosmological constant model and the vacuum energy model are also just hypotheses and models. Therefore, an entity that has positive energy and exerts negative pressure is also just a hypothesis and a model.
ΛCDM model assumes an entity with positive energy density but exerting negative pressure. However, there is a serious problem with this negative pressure claim.
1)Positive energy density (positive mass density) and negative pressure are logically contradictory because the source of pressure is kinetic energy
In order to exert negative pressure, a negative kinetic energy component is required, and in order to have negative kinetic energy, it appears that one must have a negative mass or imaginary velocity. However, because it assumes positive mass density (from the positive energy density), it seems to be a contradictory claim in itself.
2)Even in the case of light with the greatest kinetic energy component relative to the total energy, the pressure is P=(1/3)ρ. Expressing the mainstream argument slightly differently, we can express it as follows:
P= -ρ = -3((1/3)ρ)
The claims of the vacuum energy model require a being with a kinetic energy three times (P_Λ=−ρ_Λ=−3((1/3)ρ_Λ)) greater than that of light.
There are other problems with the claim that it exerts negative pressure while having positive energy density. I will skip over them because they are not important to this article. In any case, the negative pressure claim is not yet a confirmed truth, and it is also a hypothesis and a model.
The accelerated expansion of the universe can also be explained by negative mass or negative energy. In other words, negative mass or negative energy is one of the candidates for the accelerated expansion of the universe.
However, times change, and sometimes objects that seemed impossible to exist come into existence. The universe is currently expanding at an accelerating rate, and since gravity is the dominant force on a cosmic scale, a repulsive force or anti-gravity is needed for the universe to expand at an accelerating rate, which is a phenomenon that can be explained by the existence of negative mass.
The current standard cosmology is the ΛCDM model. This model explains the dark energy problem by introducing a entity that has positive energy density and exerts negative pressure.
However, cracks in this ΛCDM model have been increasing recently, and accordingly, the time is approaching when other possibilities and interpretations should be seriously examined.
The ΛCDM model consists of Λ(Lambda) and CDM(Cold Dark Matter), but it has not succeeded in explaining the source of Λ, which is the core, and the vacuum energy, which was a strong candidate, has an unprecedented error of 10^120 between the theoretical value and the observed value.
CDM has also not been discovered despite continued experiments. In addition, particle accelerator experiments, which are a completely different approach from WIMP detectors, have not found a candidate for CDM.
Furthermore, the existence of the Hubble tension problem has recently become clear, and in January 2024, the DES (Dark Energy Survey) team raised the possibility that the cosmological constant model may be wrong, and in April 2024, the DESI (Dark Energy Spectroscopic Instrument) team announced results suggesting that the cosmological constant model may be wrong. Since it is only the first year of results, we will have to wait a little longer for the final results.
1)Dark Energy Survey team
https://noirlab.edu/public/news/noirlab2401/?lang
The standard cosmological model is known as ΛCDM, or ‘Lambda cold dark matter’. This mathematical model describes how the Universe evolves using just a few features such as the density of matter, the type of matter and the behavior of dark energy. While ΛCDM assumes the density of dark energy in the Universe is constant over cosmic time and doesn’t dilute as the Universe expands, the DES Supernova Survey results hint that this may not be true.
An intriguing outcome of this survey is that it is the first time that enough distant supernovae have been measured to make a highly detailed measurement of the decelerating phase of the Universe, and to see where the Universe transitions from decelerating to accelerating. And while the results are consistent with a constant density of dark energy in the Universe, they also hint that dark energy might possibly be varying. “There are tantalizing hints that dark energy changes with time,” said Davis, “We find that the simplest model of dark energy — ΛCDM — is not the best fit. It’s not so far off that we’ve ruled it out, but in the quest to understand what is accelerating the expansion of the Universe this is an intriguing new piece of the puzzle. A more complex explanation might be needed.”
2)Dark Energy Spectroscopic Instrument team
https://arstechnica.com/science/2024/04/dark-energy-might-not-be-constant-after-all/#gsc.tab=0
"It's not yet a clear confirmation, but the best fit is actually with a time-varying dark energy," said Palanque-Delabrouille of the results. "What's interesting is that it's consistent over the first three points. The dashed curve [see graph above] is our best fit, and that corresponds to a model where dark energy is not a simple constant nor a simple Lambda CDM dark energy but a dark energy component that would vary with time.
Through the acceleration equation, we know that the universe is expanding at an accelerating rate.
In the acceleration equation, (c=1)
(1/R)(d^2R/dt^2) = -(4πG/3)(ρ+3P)
In order for the universe to accelerate, the right side must be positive, and therefore, (ρ+3P) must be negative. Here ρ is the mass density, so for the universe to expand acceleratingly, (ρ+3P)<0, and by dimensional analysis, this requires a negative mass density.
This is a phenomenon that can be explained if there is a negative mass density or negative pressure. Currently, the mainstream explains the accelerated expansion of the universe by assuming an entity with negative pressure.
However, we still do not know what the source of dark energy is. So, the cosmological constant model and the vacuum energy model are also just hypotheses and models. Therefore, an entity that has positive energy and exerts negative pressure is also just a hypothesis and a model.
ΛCDM model assumes an entity with positive energy density but exerting negative pressure. However, there is a serious problem with this negative pressure claim.
1)Positive energy density (positive mass density) and negative pressure are logically contradictory because the source of pressure is kinetic energy
Note that the effect of the pressure P is to slow down the expansion (assuming P>0). If this seems counterintuitive, recall that because the pressure is the same everywhere in the universe, both inside and outside the shell, there is no pressure gradient to exert a net force on the expanding sphere. The answer lies in the motion of the particles that creates the fluid’s pressure. The equivalent mass of the particle’s kinetic energy creates a gravitational attraction that slows down the expansion just as their actual mass does.
- An Introduction to Modern Astrophysics P1161)
Pressure in the kinetic theory of gases
3P=(Nmv^2)/Volume
In order to exert negative pressure, a negative kinetic energy component is required, and in order to have negative kinetic energy, it appears that one must have a negative mass or imaginary velocity. However, because it assumes positive mass density (from the positive energy density), it seems to be a contradictory claim in itself.
2)Even in the case of light with the greatest kinetic energy component relative to the total energy, the pressure is P=(1/3)ρ. Expressing the mainstream argument slightly differently, we can express it as follows:
P= -ρ = -3((1/3)ρ)
The claims of the vacuum energy model require a being with a kinetic energy three times (P_Λ=−ρ_Λ=−3((1/3)ρ_Λ)) greater than that of light.
There are other problems with the claim that it exerts negative pressure while having positive energy density. I will skip over them because they are not important to this article. In any case, the negative pressure claim is not yet a confirmed truth, and it is also a hypothesis and a model.
The accelerated expansion of the universe can also be explained by negative mass or negative energy. In other words, negative mass or negative energy is one of the candidates for the accelerated expansion of the universe.