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Dark Matter and Dark Energy




Saul Perlmutter
Fritz Zwicky

Hello guys and welcome back to my blog!!



Today we are goimg to talk about Dark matter and Dark Energy Both of which are decisive to the future of the universe

In the early 1990s, one thing was fairly certain about the expansion of the universe. It might have enough energy density to stop its expansion and recollapse, it might have so little energy density that it would never stop expanding, but gravity was certain to slow the expansion as time went on. Granted, the slowing had not been observed, but, theoretically, the universe had to slow. The universe is full of matter and the attractive force of gravity pulls all matter together. Then came 1998 and the Hubble Space Telescope (HST) observations of very distant supernovae that showed that, a long time ago, the universe was actually expanding more slowly than it is today. So the expansion of the universe has not been slowing due to gravity, as everyone thought, it has been accelerating. No one expected this, no one knew how to explain it. But something was causing it.


Dark matter :




By fitting a theoretical model of the composition of the universe to the combined set of cosmological observations, scientists have come up with the composition that we described above, ~ 68% dark energy, ~ 27% dark matter, ~ 5% normal matter (According to NASA sources). What is dark matter?

Dark matter is a hypothetical form of matter that is thought to account for approximately 85% of the matter in the universe and about a quarter of its total energy density.

We are much more certain what dark matter is not than we are what it is. It is dark, meaning that it is not in the form of stars and planets that we see. Observations show that there is far too little visible matter in the universe to make up the 27% required by the observations. Dark matter is not Antimatter, because we do not see the unique gamma rays that are produced when antimatter annihilates with matter. High concentrations of matter bend light passing near them from objects further away, but we do not see enough lensing events to suggest that such objects to make up the required 27% dark matter contribution. 

Maybe the discovery of Higgs Boson will help the CERN to give us answers...

Then What is it that you great minded Physics lovers Think ???????
( Let me know in the comments )

Dark Energy :



What is surprising is that Dark energy composes 68% of the Universe and we still don't know much about it.....

Dark Energy is a hypothetical form of energy that exerts a negative, repulsive pressure, behaving like the opposite of gravity. It has been hypothesised to account for the observational properties of distant type Ia supernovae, which show the universe going through an accelerated period of expansion. Like Dark Matter, Dark Energy is not directly observed, but rather inferred from observations of gravitational interactions between astronomical objects.

It is thought that the very early universe also went through a period of rapid expansion, called inflation. Inflation, occurring about 10−36 seconds after the Big Bang, acted to smooth out the universe and make it geometrically flat. If the density of the universe exactly equals the critical density, then the geometry of the universe is flat like a sheet of paper. For a matter dominated Universe the critical density (equivalent to about 6 protons per m3) sits exactly between the density required for a heavy universe that will eventually collapse, and a density required for a lightuniverse that will expand forever. When astronomers measure the amount of matter and energy in the universe today they only come up with about ~30% of what is needed to make the universe flat. The addition of Dark Energy to the mass-energy budget makes the universe flat. The simplest version of inflation, predicts that the density of the universe is very close to the critical density.



Maybe the discovery of Higgs Boson will help the CERN to give us answers...

Then What is it that you great minded Physics lovers Think ???????
( Let me know in the comments )

So guys that's it for today...

I will be back Tomorrow with an article about the Higgs Boson 
Be ready for it 

Till then Bye

Your
Universal Physics Expert

Signing Off
Khushil

Comments

  1. Khushil Shah14 May 2019 at 18:35

    What do you think they consist offf ?????
    Tell me in the comments

    Do you understand what am I teaching ?????

    ReplyDelete
    Replies
    1. Ishana's sea of words has a pearl for you3 February 2020 at 21:26

      Dark matter and dark energy are really intriguing concepts... About what you are teaching, I think that's pretty less insight on the topic... But good work of course.
      And about the existence of dark matter, I will recommend you to read an article about how the approximations of percentage of dark matter could be just a mistake of the scientists in mark mahin's blog which is futureandcosmos.blogspot.com

      Delete

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