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Author Topic: Why do we need dark energy to explain expansion of the universe?  (Read 4546 times)

Offline opaque

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I'm not a science major, but I think a lot about the cosmos.

So my question is Why do we need dark energy to explain expansion of the universe?

Dark matter is used to explain why galaxies stay together. Because without it they would fly apart. Then we had to explain why everything was flying apart. Dark energy.

Don't they seem to cancel each other out?

And furthermore, if we do need dark energy to explain things, couldn't it be just gravity from other universes pulling at ours?


 

Offline PmbPhy

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Quote from: opaque
So my question is Why do we need dark energy to explain expansion of the universe?
Welcome to the forum!

We don't need dark energy to explain the expansion of the universe. In fact before the 21st century it was explained without dark energy. All dark energy does is explain, not why the universe is expanding, but why the universe is expanding at an accelerating rate

Quote from: opaque
Dark matter is used to explain why galaxies stay together. Because without it they would fly apart.
No. That's now what it's used for. Normal gravity keeps the galaxy together. Dark matter is used to explain the anomalous speeds of the matter circling around the center of the galaxy.

Quote from: opaque
And furthermore, if we do need dark energy to explain things, couldn't it be just gravity from other universes pulling at ours?
No. The gravitational fields in other universes do not have an effect on the matter in other universes than themselves.

Question: May I ask where you got these notions of what dark matter is and why its existence has been postulated?
« Last Edit: 14/10/2014 04:52:06 by PmbPhy »
 

Offline lightarrow

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Quote from: opaque
So my question is Why do we need dark energy to explain expansion of the universe?
Welcome to the forum!
We need dark energy to be able to describe something called the rotation curves of galaxies.
you are talking about dark Matter here, not dark Energy 😊

--
lightarrow
 

Offline ScientificSorcerer

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Dark matter comes from astronomers refusing to take into account and acknowledge the electromagnetic attraction forces which keep galaxies together.

Dark energy is not a continuous expansion of the universe, It is the result of massive gravity waves which were generated during the big bang and still ripple the fabric of space to this day in the form of waves. Because when the big bang's singularity imploded and converted all of it's mass into energy the sudden change of mass and gravity caused ripples called gravity waves to propagate through space.

Each wave is ridiculously huge, spanning millions of light years per wave length.
« Last Edit: 13/10/2014 19:23:16 by ScientificSorcerer »
 

Offline chiralSPO

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Dark matter comes from astronomers refusing to take into account and acknowledge the electromagnetic attraction forces which keep galaxies together.

Dark energy is not a continuous expansion of the universe, It is the result of massive gravity waves which were generated during the big bang and still ripple the fabric of space to this day in the form of waves. Because when the big bang's singularity imploded and converted all of it's mass into energy the sudden change of mass and gravity caused ripples called gravity waves to propagate through space.

Each wave is ridiculously huge, spanning millions of light years per wave length.

I'm not familiar with these explanations. Where did they come from?
 

Offline Bill S

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Quote from: Pete
That's now what it's used for. Normal gravity keeps the galaxy together. Dark matter is used to explain the speeds of the matter circling around the center of the galaxy.

The first explanation I read about dark matter and its influence on the rotation of galaxies stated that the galaxies were rotating at such a speed that without the extra mass they would fly apart.  I don't remember now where that was, but it was almost certainly a Pop Sci book or a magazine article.
 

Offline PmbPhy

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Quote from: lightarrow
We need dark energy to be able to describe something called the rotation curves of galaxies.
you are talking about dark Matter here, not dark Energy 😊
[/quote]
You're right. I'll go back and correct it. Thanks. I don't know what's with me lately!!
« Last Edit: 14/10/2014 04:53:11 by PmbPhy »
 

Offline PmbPhy

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Quote from: ScientificSorcerer
Dark matter comes from astronomers refusing to take into account and acknowledge the electromagnetic attraction forces which keep galaxies together.
That's quite untrue. There are no such forces between galaxies. There aren't even any forces between astrophysical bodies. Where did you get these ideas from?

Quote from: ScientificSorcerer
Dark energy is not a continuous expansion of the universe, It is the result of massive gravity waves which were generated during the big bang and still ripple the fabric of space to this day in the form of waves.
Wrong again. Dark energy is responsible for the accelerated expansion for the universe which is expanding in a uniform and continuous manner.

Quote from: ScientificSorcerer
Because when the big bang's singularity imploded and converted all of it's mass into energy the sudden change of mass and gravity caused ripples called gravity waves to propagate through space.
What change in mass are you talking about?? Also there's no evidence of such an singularity and the such a thing is not even part of the Big Bang theory.

Quote from: ScientificSorcerer
Each wave is ridiculously huge, spanning millions of light years per wave length.
What are you basing this on?

ScientificSorcerer- This forum is for mainstream physics, not your own personal theories. If you want to talk about this you need to start a new thread in the "New Theories" forum below.
 

Offline acsinuk

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    • electricmagnofluxuniverse.blogspot.com
Dark matter and dark energy are irrelevant in a magnetised universe as the forces generated electromagnetically must definitely be taken into account.
At present we cannot explain massless electromagnetic energy using the MKS system as it has energy as M*L/T^2*L.  This scalar energy is not 3D magnoflux fundamental energy which is basically what the magnetised space between stellar bodies and indeed the inside electron space in molecules stuff is made of.
We need to expand the MKS standard international units to VICos$MKS units and then the magnoflux massless 3D energy can be defined and the universe balanced, and galaxies spun.
That's the only way forward I can think of.                                          CliveS
 

Offline PmbPhy

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Quote from: acsinuk
Dark matter and dark energy are irrelevant in a magnetised universe as the forces generated electromagnetically must definitely be taken into account.
The contributions from the electric field is basically zero since the net electric field in the universe is zero with small exceptions. The exceptions are so small as not have any measurable effect on cosmological dynamics.

Quote from: acsinuk
At present we cannot explain massless electromagnetic energy using the MKS system as it has energy as M*L/T^2*L.
That's not true. Electromagnetic energy is well defined and works according to theory and laboratory experiments verify this.

Quote from: acsinuk
This scalar energy is not 3D magnoflux fundamental energy which is basically what the magnetised space between stellar bodies and indeed the inside electron space in molecules stuff is made of.
What are you talking about? Magnoflux is not a term found in electrodynamics, at least not in English. Also space is not magnetized. There are exceptions but nothing that will effect cosmological dynamics if ignored.

Also it makes no difference what units are used. The physics is the same as are what happens in nature.
 

Offline acsinuk

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    • electricmagnofluxuniverse.blogspot.com
I disagree, the galaxies are all magnetised but we cannot measure the field as we have no reference point to measure from!  The reasoning that electromagnetic energy must be associated with particles makes no sense; we know its massless but we still need to force it forwards electrically and this is achieved by applying a curling electromotive force in VOLTS not Newton which go in one direction only.
 

Offline chiralSPO

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I disagree, the galaxies are all magnetised but we cannot measure the field as we have no reference point to measure from!  The reasoning that electromagnetic energy must be associated with particles makes no sense; we know its massless but we still need to force it forwards electrically and this is achieved by applying a curling electromotive force in VOLTS not Newton which go in one direction only.

This makes no sense to me.
 

Offline PmbPhy

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Quote from: acsinuk
I disagree, the galaxies are all magnetised,...
Disagreeing only comes into play when the subject is a matter of opinion. Whether the galaxy is magnetized or not is not a matter of opinion. It's an observed fact that astrophysicists have never observed anything in is nature which suggests that the universe is magnetized. There simply isn't a source of magnetism to do it.

Exactly what are you basing your claims on?

Quote from: acsinuk
..but we cannot measure the field...
So if we can't measure it then the universe behaves exactly as it would if it wasn't magnetized. Therefore you have no basis for making such a claim.


Quote from: acsinuk
The reasoning that electromagnetic energy must be associated with particles makes no sense; ...
Who said that they were? That only applies to charged particles. However the nucleus has charged particles in it and there is electrostatic potential energy "stored" in the nucleus.

However charged particles have electromagnetic energy.

Quote from: acsinuk
we know its massless but we still need to force it forwards electrically and this is achieved by applying a curling electromotive force in VOLTS not Newton which go in one direction only.
You sure aren't being very clear. What particles are you referring to? If its photons then you're confusing rest mass and relativistic mass. The mass density for radiation is non-zero. Einstein proved this back in 1906. You can follow the derivation here; http://home.comcast.net/~peter.m.brown/sr/einsteins_box.htm
 

Offline PmbPhy

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Quote from: chiralSPO
This makes no sense to me.
I'm with you my friend!
 

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