Dark energy - Expansion of the universe

In summary, the conversation discussed the concept of dark energy and its relation to the expansion of the universe. While it is known that the universe is expanding and accelerating, the source of this energy is still unknown. This is referred to as dark energy. Similarly, the existence of dark matter, which does not interact with electromagnetic radiation but can be detected through its gravitational effects, is also a mystery. Various theories and candidates, such as WIMPs, have been proposed but the true nature of dark matter is still uncertain.
  • #1
teddd
62
0
Hi everyone!

Could you explain me how is the dark energy related to the expansion of the universe??


Thanks!
 
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  • #2
It is the cosmological constant in the Einstein Field Equations.
 
  • #3
We don't really know what it is; what we do know is what we observe: that the universe is expanding and accelerating.

Even without knowing anything more about what is causing this expansion, we know it will require energy to do so. Whatever form it takes, we call it Dark Energy.
 
  • #4
But why the problem of the accelerating universe is addressing to some missing mass? how can we state that? From the einstein field equation?
 
  • #5
teddd said:
But why the problem of the accelerating universe is addressing to some missing mass? how can we state that? From the einstein field equation?

Please rephrase.
 
  • #6
DaveC426913 said:
We don't really know what it is; what we do know is what we observe: that the universe is expanding and accelerating.

Even without knowing anything more about what is causing this expansion, we know it will require energy to do so. Whatever form it takes, we call it Dark Energy.

I'm going to respectfully ask if it isn't just a bit bold to claim that "we know...the universe is expanding and accelerating".

Wouldn't it be wiser and safer to say:
We observe the angular rotation of galaxies and currently prefer dark matter as an explanation.
We observe the redshift of quasars and currently prefer an accelerating universe/dark energy as an explanation.

It is very uncomfortable to put all one's eggs in the basket of invisible and potentially perpetually undetectable forms of matter and energy, and blithely say it adds up to 94% of the universe. That's too great a leap of faith for me to accept such explanations as chiseled into the stone of certainty.

In my lifetime, a number off these sorts of explanations have been propounded as the state of the art. I think it's too soon to be anything other than skeptical.

Respectfully,
Steve
 
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  • #7
Dotini said:
I'm going to respectfully ask if it isn't just a bit bold to claim that "we know...the universe is expanding and accelerating".

Wouldn't it be wiser and safer to say:
We observe the angular rotation of galaxies and currently prefer dark matter as an explanation.
We observe the redshift of quasars and currently prefer an accelerating universe/dark energy as an explanation.
That's pretty much what I am saying.

We observe the universe ot be expanding. We don't know why, but through some mathematical origami, it can be viewed as energy.

Even if we have no idea of the source or manifestation of the energy.


Think of it kind of like this: a ball is magically lifted from the ground to the table. We have no idea what lifted it there, yet we can still confidently figure out how much energy this magical movement required.
 
  • #8
Dark matter and dark energy is something that is completely unaccounted for. As some of you pointed out we can measure that the universe is expanding, and we're pretty sure it's correct, I think it was Edwin Hubble who discovered that galaxy's was moving away from us (our horizon in space is centered on Earth) and galaxy's further away is moving faster away from us while nearby galaxy's is moving with a lesser speed which is very similar to an explosion in this case the big bang. It requires energy for an accelerating expanding universe and we don't understand what it is = dark energy. When we talk about dark matter it is another "thing" where we are completely ignorant of what accounts for it. We don't know if its matter, we know its there because we feel its gravitation so dark gravity might be the right placeholder term until we figure out what it is. Until then dark energy and dark matter could be called Christian and Martin - we have no idea what they are.

/WeW
 
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  • #9
Whateverworks said:
Dark matter and dark energy is something that is completely unaccounted for. As some of you pointed out we can measure that the universe is expanding, and we're pretty sure it's correct, I think it was Edwin Hubble who discovered that galaxy's was moving away from us (our horizon in space is centered on Earth) and galaxy's further away is moving faster away from us while nearby galaxy's is moving with a lesser speed which is very similar to an explosion in this case the big bang. It requires energy for an accelerating expanding universe and we don't understand what it is = dark energy. When we talk about dark matter it is another "thing" where we are completely ignorant of what accounts for it. We don't know if its matter, we know its there because we feel its gravitation so dark gravity might be the right placeholder term until we figure out what it is. Until then dark energy and dark matter could be called Christian and Martin - we have no idea what they are.

/WeW

Dark gravity?
The thing which separates any normal-baryonic matter to dark matter is the fact that 'dark matter' as the name suggests does not influence Electromagnetic radiation at all,gravitation however does influence it. Numerous categories of candidates have been theorized however WIMPS have come out as notable candidates in recent studies.
-ibysaiyan
 
  • #10
ibysaiyan said:
Dark gravity?
The thing which separates any normal-baryonic matter to dark matter is the fact that 'dark matter' as the name suggests does not influence Electromagnetic radiation at all,gravitation however does influence it. Numerous categories of candidates have been theorized however WIMPS have come out as notable candidates in recent studies.
-ibysaiyan

Hello Ibysaiyan.

It's correct that "dark matter" does not interact with electromagnetic radiation in any way. However, as you pointed out, gravitation does influence it. Weakly interacting massive particles could be the right hypothesis but until then I would suggest that "dark matter" is a name that could lead to a misconception but equally dark gravity might and probably will do the same.

Respectfully

/WeW
 
  • #11
I think dark matter will eventually prove to be more than one particle species. Perhaps WIMP's, axions, neutralinos and other exotics are all out there hiding.
 

What is dark energy?

Dark energy is a hypothetical form of energy that is believed to permeate all of space and contribute to the accelerating expansion of the universe.

How was dark energy discovered?

The existence of dark energy was first proposed in 1998 when astronomers observed that the expansion of the universe was accelerating rather than slowing down as expected.

What is the relationship between dark energy and the expansion of the universe?

Dark energy is thought to be the driving force behind the expansion of the universe. It is believed to counteract the gravitational pull of matter, causing the universe to expand at an accelerating rate.

How does dark energy differ from dark matter?

Dark energy and dark matter are two separate and distinct concepts. Dark matter is believed to be a type of matter that does not emit or absorb light, while dark energy is a form of energy that is responsible for the expansion of the universe.

What are the implications of dark energy for the future of the universe?

If dark energy continues to accelerate the expansion of the universe, it is likely that the universe will eventually reach a state of "heat death" where all matter and energy are evenly distributed and there is no more potential for work or life to exist.

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