- #1
Philosopha
- 46
- 0
Why do we talk about dark matter rather than dark mass?
Where does the necessity for matter stem from?
Where does the necessity for matter stem from?
Last edited:
Mordred said:Dark mass is a combination of the mass of dark energy and dark matter.
mass is either due to energy or matter. Dark matter explains why galaxies rotate at the rate that they do. Why certain gravitational lenses exists.
We do not fully understand DM. However there is plenty of indirect evidence that it is there.
Philosopha said:Thx Mordred. Is there any 'specific' evidence apart from the gravitational effects? How much does the mass of DE contribute to DM? Could it be around 66% (own figure).
cepheid said:Look, just to be clear, 'dark mass' is not really an accepted term in the cosmological literature. It means nothing: it's something you just made up.
DM is dark matter, and DE is dark energy, and these are two totally different things.
These two things contribute a certain amount to the total "budget" of energy density (energy per unit volume) in the universe. If you want to know how much: dark energy contributes to about 73% of the total energy density of the universe, and dark matter contributes about 22%. So that means that 95% of the energy density in the universe is due to two constituents of the universe that we don't fully understand yet, and only 5% of the energy density of the universe is due to the mass-energy of ordinary matter that is composed of atoms (and that includes everything that we can see).
Philosopha said:I think the latest figures from Planck are 68.3% DE, 26.8% DM, 4.9% visible.
Philosopha said:And 4.9/26.8 = 18.3 visible to 81.7% invisible? Why do they say it's roughly 84%?
Philosopha said:I'm using the word "mass" (which is like energy) just to be careful because of the lack of evidence for matter particles other than for the gravitational effect which the "unknown" causes. Just wondering if there is a bulletproof reason that it cannot be any other way than "matter" because of course the word must have been chosen with good reason.
Mordred said:There is a mass energy relation. Dark energy does contribute to the total mass energy of the universe.
Mordred said:However your correct in that its never referred to as dark mass. However if you want to tally the total mass if the universe. Dark energy density is also included in the calculations.
Mordred said:however I should note that dark energy is considered vacuum energy so converting from energy density to mass. affects the critical density differently from say dark matter or baryonic matter.
I fully agree dark mass is a poor term for the latter reason.
Dark Matter is a theoretical type of matter that is believed to exist in the universe but does not interact with light, making it invisible. It is thought to make up about 85% of the total matter in the universe. On the other hand, Dark Mass refers to the total amount of matter, both visible and invisible, in the universe. This includes Dark Matter as well as regular matter that can be detected through light.
Dark Matter can only be indirectly detected through its gravitational effects on visible matter. Scientists use various methods such as observing the rotation of galaxies, studying the bending of light, and mapping the distribution of matter in the universe to measure the presence of Dark Matter. Dark Mass, on the other hand, can be measured using traditional methods of measuring mass, such as gravitational interactions and the Doppler effect.
The composition of Dark Matter is still a mystery, as it cannot be observed directly. However, scientists have proposed various theories, such as weakly interacting massive particles (WIMPs) and axions. Dark Mass, on the other hand, is thought to consist of Dark Matter, regular matter, and potentially other forms of matter that have not yet been discovered.
The existence of Dark Matter and Dark Mass is crucial in explaining many observed phenomena in the universe. Without these invisible forms of matter, the current understanding of gravity and the structure and evolution of the universe would not be able to fully explain the observations. Therefore, the study of Dark Matter and Dark Mass is essential in furthering our understanding of the universe.
Yes, there is a significant amount of evidence for the existence of Dark Matter and Dark Mass. This includes observations of the rotation of galaxies, gravitational lensing, and the distribution of matter in the universe. However, the exact nature and composition of these invisible forms of matter are still unknown, and further research and observations are needed to fully understand them.