The Percentage of dark matter

In summary, the findings of the Wilkinson Microwave Anisotropy Probe suggest that the % of dark matter, atoms, and dark energy in a 6x10^9 years old universe is similar to the present universe. However, the % of photons is much lower, at 43%. This suggests that dark energy played a significant role in the early stages of the universe.
  • #36
Estimates for z=1, around year 6 billion.
DM + ordinary matter .27*8/2.89 = 0.7474... ≈ 75%

Dark matter: .23*8/2.89 = 0.6367... ≈ 64%
Ordinary: .04*8/2.89 = 0.1107 ≈ 11%
Photons < 1%
Neutrinos < 1%

The point is that (as percents of the then critical density) the values for Photons and Neutrinos are only about 5 times what they are today and today both are so close to 0% of critical that, as you can see, NASA website does not even show them in the pie chart (you would need a magnifying glass to see the pie slice.)
:biggrin:
 
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  • #37
Dynamotime said:
Anyway I came up with my final numbers for a 6 billion old universe:
50.165% Dark Matter, 40.28% Dark Energy and 9.552% Atoms
...

For comparison
64% Dark Matter, 25% "Dark Energy" (i.e. cosmological constant), 11% "Atoms" (i.e. ordinary matter)

In either case the photon and neutrino fraction are small and don't affect either the rough percentages or the conclusion.
 
  • #38
Dynamotime said:
I have a hard time with dark matter/matter and energy having a constant ration existing between them, and the apparition of dark energy 7 billion years ago from nowhere.

So does everyone else. But it's the "least weird" explanation for what we see.

Anyway the image below illustrates the Cosmology standard model in a 13.7 billion years’ time line.

You have to be careful with popular explanations, these are "cartoon diagrams" that leave out of a lot of things.

In my hypothesis it is no need of a theory of inflation, only dark energy and "mass" explain the size of the today universe, because in my hypothesis dark energy did not appear from nowhere but had a constant influence on the expansion of the universe from the beginning of it.

The problem is that if you assume that there is some early expansion, then you have problems with things like big bang nucleosynthesis, CMB measurements, and galaxy counts. For example, if you have lots of early expansion, then the universe cools after which affects the composition of the universe. Things fly away from each other more quickly which means that the universe is less lumpy.
 
  • #39
Dynamotime said:
I do not believed the photon is part of dark energy, I “lump “them together because photon aka light conceal the presence of dark energy, in another word we cannot see dark energy because the light.

It might help here to replace "dark energy" with "mystery pressure". You have two forces in the universe, gravity that tries to hold things together. "pressure" that causes things to fly apart. And then the initial condition.

"Gravity" is easy to model since gravity is gravity is gravity.

The hard thing to model is "pressure". Since you have you to make assumptions about what causes the pressure.

Now the thing about matter is that the more density you have, the higher the pressure. The same goes true with radiation. One of the candidates for the "mystery pressure" is a constant that exerts constant pressure regardless of density.

So what happens is that in the early universe, things were hotter and denser, so most of the pressure comes from matter and radiation. As the universe cools, the pressure from radiation and matter decreases, leaving behind the "constant pressure" which they becomes observable.

If You can see the light from 13.7 billion years ago, it means that the light was not absorb by matter so it still conceal the presence of dark energy from 13.7 billion years ago

But we can tell from other things that the "mystery pressure" wasn't important in the early universe.

Again In my hypothesis Light and/or matter with no mass conceal the presence of dark energy.

Light has mass. Also if you think of dark energy as "mystery pressure" that's sort of what already happens, and people have already worked out the necessary equations.
 
<h2>1. What is dark matter?</h2><p>Dark matter is a type of matter that does not emit or interact with light, making it invisible to telescopes and other instruments used to study the universe. It is thought to make up about 85% of the total matter in the universe.</p><h2>2. How do scientists measure the percentage of dark matter?</h2><p>Scientists use a variety of methods to measure the percentage of dark matter in the universe. One common method is to study the rotation of galaxies and the movement of stars within them, as dark matter has a gravitational influence on these objects. Other methods include studying the cosmic microwave background radiation and the distribution of matter in the universe.</p><h2>3. Why is the percentage of dark matter important to study?</h2><p>The percentage of dark matter is important to study because it is believed to play a significant role in the formation and evolution of galaxies and the overall structure of the universe. Understanding the amount and distribution of dark matter can also help us better understand the nature of gravity and the fundamental laws of physics.</p><h2>4. Can dark matter be detected or observed directly?</h2><p>No, dark matter cannot be detected or observed directly because it does not interact with light. However, scientists are working on developing new technologies and experiments to try and detect dark matter indirectly through its gravitational effects.</p><h2>5. Is the percentage of dark matter the same everywhere in the universe?</h2><p>Currently, scientists believe that the percentage of dark matter is roughly the same throughout the universe. However, there may be variations in the distribution of dark matter in different regions, which is an area of ongoing research and study.</p>

1. What is dark matter?

Dark matter is a type of matter that does not emit or interact with light, making it invisible to telescopes and other instruments used to study the universe. It is thought to make up about 85% of the total matter in the universe.

2. How do scientists measure the percentage of dark matter?

Scientists use a variety of methods to measure the percentage of dark matter in the universe. One common method is to study the rotation of galaxies and the movement of stars within them, as dark matter has a gravitational influence on these objects. Other methods include studying the cosmic microwave background radiation and the distribution of matter in the universe.

3. Why is the percentage of dark matter important to study?

The percentage of dark matter is important to study because it is believed to play a significant role in the formation and evolution of galaxies and the overall structure of the universe. Understanding the amount and distribution of dark matter can also help us better understand the nature of gravity and the fundamental laws of physics.

4. Can dark matter be detected or observed directly?

No, dark matter cannot be detected or observed directly because it does not interact with light. However, scientists are working on developing new technologies and experiments to try and detect dark matter indirectly through its gravitational effects.

5. Is the percentage of dark matter the same everywhere in the universe?

Currently, scientists believe that the percentage of dark matter is roughly the same throughout the universe. However, there may be variations in the distribution of dark matter in different regions, which is an area of ongoing research and study.

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