Theory of dark matter is based on brightness

[CaptainPanic]

If dark matter would be actual matter that can block/filter light, would it not be possible that the measurements of the distance of stars is wrong? And would it not be possible that the theory of dark matter is wrong?

 

Interstellar matter has a known composition. (Link to wikipedia).

It can be relatively easily calculated that even if all dark matter is completely transparent, the actual dust and other matter in the universe becomes of significance when we talk about the brightness of the furthest objects.

 

But if we're wrong in any of the assumptions in the interstellar matter table that I just linked to, and there is some real matter hanging somewhere in space (I dunno - the Oortcloud is a little denser, or there is a galactic version of the oortcloud?) and the absorption would be significantly different, wouldn't that screw up a few models?

 

[edited for spelling mistakes]

Edited January 24, 2011 by CaptainPanic

[alpha2cen]

Are there bubble-vacuum(there are no resources to make matter or anti-matter, my assumption) state in the Universe?

What I'd like to state is not all Dark-Matter is bubble-vacuum, but some of them might be bubble-vacuum.

Edited January 24, 2011 by alpha2cen

[swansont]

Are there bubble-vacuum(there are no resources to make matter or anti-matter, my assumption) state in the Universe?

What I'd like to state is not all Dark-Matter is bubble-vacuum, but some of them might be bubble-vacuum.

 

!

Moderator Note

I'm not sure I see the relevance to the OP, especially since you are asking a question. Please don't tack your own questions on to the thread — that's hijacking. Make a new one, or rephrase this one in terms of answering the OP.

 

If dark matter would be actual matter that can block/filter light

 

Dark matter doesn't interact with light in this way. That's why it's dark. All you have is bending due to GR.

[CaptainPanic]

Dark matter doesn't interact with light in this way. That's why it's dark. All you have is bending due to GR.

I'm assuming GR is gravity? I'm not familiar with the abbreviation, but it would make sense.

 

So, I accept that there are objects that are very heavy, and can bend light. And I am not saying that there is no dark matter involved - it might well be. (I don't know enough about it anyway).

 

I guess I should have said that if there is significantly more non-luminous matter in space, could that influence our models?

 

Do we know for a fact that the light (or other radiation) that arrives in our telescopes hasn't been through a dust cloud that simply absorbed or otherwise changed a certain percentage of the light/radiation?

[D H]

I'm assuming GR is gravity? I'm not familiar with the abbreviation, but it would make sense.

GR is short for general relativity.

 

 

 

Do we know for a fact that the light (or other radiation) that arrives in our telescopes hasn't been through a dust cloud that simply absorbed or otherwise changed a certain percentage of the light/radiation?

This is not what dark matter is about. The problem is that the motion of the matter (stars and galaxies) that we can see does not jibe with the what gravitational models say those motions should be -- assuming that what we see gives us a picture of the matter that matters (as far as predicting motion is concerned). There are only a few of ways around this problem:

 

1. Our models of gravity are wrong.

2. We aren't seeing all the matter that matters.

3. Both of the above are true.

 

Option 2 combined with the fact that we can see so far and so clearly into the universe rules out a lot of possibilities. Astronomers have pretty much ruled out regular matter of all sorts, including dust. If option 2 is the case, whatever it is that is making our observations and predictions disagree is something rather exotic.

 

Option 1 is problematic for a couple of reasons. First off, our models of gravity do jive with a lot of what we can see, including very, very far into the universe. Another problem is that every proposed alternative to general relativity so far, including some rather borderline crackpot ideas, still requires option 2.

 

There are couple of good reasons most astronomers and physicists go with option 2 rather than option 1. One reason, a weird mix of arrogance and humility, is that it is much easier to conjecture that some unknown type of matter exists than it is to think that our basic model of gravitation is wrong. A better reason is that multiple models that go "beyond the standard model", including string theory, propose various candidates that fit the bill rather nicely.

Edited January 25, 2011 by D H

[Janus]

If dark matter would be actual matter that can block/filter light, would it not be possible that the measurements of the distance of stars is wrong? And would it not be possible that the theory of dark matter is wrong?

 

Interstellar matter has a known composition. (Link to wikipedia).

It can be relatively easily calculated that even if all dark matter is completely transparent, the actual dust and other matter in the universe becomes of significance when we talk about the brightness of the furthest objects.

 

 

 

Anything that absorbs light (other than black holes) would have to radiate away the energy it absorbed, this would cause it to "glow" at some electromagnetic frequency. Since we explore the universe over a large range of the electromagnetic spectrum and not just the visible part, we would dectect this radiation.

[dragonstar57]

Anything that absorbs light (other than black holes) would have to radiate away the energy it absorbed, this would cause it to "glow" at some electromagnetic frequency. Since we explore the universe over a large range of the electromagnetic spectrum and not just the visible part, we would dectect this radiation.

would it be detectable if it just scattered the incoming light?

[swansont]

would it be detectable if it just scattered the incoming light?

 

Scattering requires an electromagnetic interaction.

[alpha2cen]

If dark matter would be actual matter that can block/filter light, would it not be possible that the measurements of the distance of stars is wrong? And would it not be possible that the theory of dark matter is wrong?

 

[edited for spelling mistakes]

 

Till now the other thing is not known which interacts with light without matter and gravity.

To obtain dark matter effect, some potion of light through some place in the space must be slow down.

what does make the light slow down without absorption? It would be gravity.

The one give gravity at the place in the space is Dark Matter. That is today's conclusion.

But I have one doubt that" Is the speed of light through the vacuum in all Universe is same?"

i.e. homogenity of vacuum property against light.

If all vacuum property in the Universe is same against light, the Dark Matter theory will have no paradox.

[steevey]

If dark matter would be actual matter that can block/filter light, would it not be possible that the measurements of the distance of stars is wrong? And would it not be possible that the theory of dark matter is wrong?

 

Interstellar matter has a known composition. (Link to wikipedia).

It can be relatively easily calculated that even if all dark matter is completely transparent, the actual dust and other matter in the universe becomes of significance when we talk about the brightness of the furthest objects.

 

But if we're wrong in any of the assumptions in the interstellar matter table that I just linked to, and there is some real matter hanging somewhere in space (I dunno - the Oortcloud is a little denser, or there is a galactic version of the oortcloud?) and the absorption would be significantly different, wouldn't that screw up a few models?

 

[edited for spelling mistakes]

 

If dark matter exists, the reason its dark is cause it doesn't interact with the electro-magnetic force, which is why it has to be dense because the only thing holding it together would be gravity. The reason there seems to be dark matter is because there isn't enough visible matter to account for things such as the gravitational fields arround certain areas as well as there not being enough visible mass to make up for how galaxies are held together.

Edited January 25, 2011 by steevey

[CaptainPanic]

Anything that absorbs light (other than black holes) would have to radiate away the energy it absorbed, this would cause it to "glow" at some electromagnetic frequency. Since we explore the universe over a large range of the electromagnetic spectrum and not just the visible part, we would dectect this radiation.

But we do measure a radiation, which is called the cosmic background radiation?

 

Why are we so certain that the cosmic background radiation originates from the big bang (or shortly after the big bang)? Why can't it be an IR emission from particles that on average receive some light, absorb it, heat up, and emit IR at about 2.7 Kelvin?

Edited January 26, 2011 by CaptainPanic

[D H]

But we do measure a radiation, which is called the cosmic background radiation?

 

Why are we so certain that the cosmic background radiation originates from the big bang (or shortly after the big bang)? Why can't it be an IR emission from particles that on average receive some light, absorb it, heat up, and emit IR at about 2.7 Kelvin?

In a sense that is exactly what the CMBR is: Light from an opaque cloud of plasma that was radiating as a black body. It appears to be a black body at 2.7 Kelvin now because of cosmological redshift. Per the big bang model, the temperature was about 3000 Kelvin when the universe cleared.

 

Is the big bang model wrong: Could the CMBR be coming from a much cooler, much closer gas cloud? The answer is no. The glow is much too uniform. That the glow is so uniform is one of the key pieces of confirming evidence for the big bang model.

 

 

[CaptainPanic]

In a sense that is exactly what the CMBR is: Light from an opaque cloud of plasma that was radiating as a black body. It appears to be a black body at 2.7 Kelvin now because of cosmological redshift. Per the big bang model, the temperature was about 3000 Kelvin when the universe cleared.

 

Is the big bang model wrong: Could the CMBR be coming from a much cooler, much closer gas cloud? The answer is no. The glow is much too uniform. That the glow is so uniform is one of the key pieces of confirming evidence for the big bang model.

Sorry for not accepting this without a struggle...

 

I agree that if the CMBR would be from a gas cloud near us, it would probably not be uniform.

However, if the CMBR is form all the interstellar particles in the entire universe, then could it not be quite uniform? After all, all the differences in density (planets, stars, galaxies and clusters) can all be considered local phenomena compared to the size of the entire universe.

[alpha2cen]

In a sense that is exactly what the CMBR is: Light from an opaque cloud of plasma that was radiating as a black body. It appears to be a black body at 2.7 Kelvin now because of cosmological redshift. Per the big bang model, the temperature was about 3000 Kelvin when the universe cleared.

 

Is the big bang model wrong: Could the CMBR be coming from a much cooler, much closer gas cloud? The answer is no. The glow is much too uniform. That the glow is so uniform is one of the key pieces of confirming evidence for the big bang model.

 

 

 

I thought about that problem before.

Let us see this site #8

http://www.scienceforums.net/topic/52871-universe-expansion-diagram/

[Janus]

Sorry for not accepting this without a struggle...

 

I agree that if the CMBR would be from a gas cloud near us, it would probably not be uniform.

However, if the CMBR is form all the interstellar particles in the entire universe, then could it not be quite uniform? After all, all the differences in density (planets, stars, galaxies and clusters) can all be considered local phenomena compared to the size of the entire universe.

 

This still doesn't work. For one, no collection of intersteller particles will absorb/scatter all frequencies of electromagnetic radiation equally. Secondly, these particles would tend to be denser in the area immediately surrounding galaxies, plus they would be receiving a stronger intensity of light. As a result, you would see a brighter "glow" surrounding galaxies.