Introducing "Dark Matter"

[juvenissun]

Black holes give off and absorb light. Dark matter only affects light through gravity, while black holes have other tell-tale signs.

If so, do we know where is the closest small black hole to the earth? Or, black holes nearby the solar system?

This is only my guess: I think we can barely detect the supermassive black hole. But a black hole of a few tens solar mass is simply too small to be detected. Right?

 

[Resha Caner]

This dark matter doesn’t sound like a placeholder term to me. It sounds like the real thing.

This comment intrigues me.

I'm thinking of this from more of a philosophical perspective than a scientific one, but at what point will we decide that we know what dark matter is?

In seems that maybe the reason physicists say they don't know is because they can see the effect but don't know the cause. Further, the implication that goes along with understanding the cause is that we can control ... or at least affect this stuff in some way.

Is that it? That we can see the effects but we can't influence the effects? Or is that not quite right?

 

[NGC 6712]

This comment intrigues me.

I'm thinking of this from more of a philosophical perspective than a scientific one, but at what point will we decide that we know what dark matter is?

In seems that maybe the reason physicists say they don't know is because they can see the effect but don't know the cause. Further, the implication that goes along with understanding the cause is that we can control ... or at least affect this stuff in some way.

Is that it? That we can see the effects but we can't influence the effects? Or is that not quite right?

The whole reason for the concept is we can measure the effects, we can even work out its distribution and we certainly know where it isn't but we have not identified what it is.

There has been quite a bit of garbage written on this thread and I'll answer some of that later. This is one of the main areas I work in.

 

[Resha Caner]

This is one of the main areas I work in.

Cool. It's always better to get the expert opinion.

The whole reason for the concept is we can measure the effects, we can even work out its distribution and we certainly know where it isn't but we have not identified what it is.

This doesn't really answer my question. I realize you can measure the effects. But, as was pointed out, if you don't know what the exotic dark matter is, the name doesn't really matter. You could call it Beauford for all the difference it makes. I suppose "dark" is an appropriate adjective, but maybe "matter" is not the appropriate descriptor.

I don't care what you call it, that's not my point. I'm curious what would need to happen to satisfy you that you know what it is. I'm suggesting that you would need the ability to produce the effect rather than just measure it. Is that part of it?

 

[Nabobalis]

Cool. It's always better to get the expert opinion.



This doesn't really answer my question. I realize you can measure the effects. But, as was pointed out, if you don't know what the exotic dark matter is, the name doesn't really matter. You could call it Beauford for all the difference it makes. I suppose "dark" is an appropriate adjective, but maybe "matter" is not the appropriate descriptor.

I don't care what you call it, that's not my point. I'm curious what would need to happen to satisfy you that you know what it is. I'm suggesting that you would need the ability to produce the effect rather than just measure it. Is that part of it?

Well as you said, what we call it atm doesn't matter.

I suspect people will be satisfied if we can identify what exactly actual particles are in dark matter. Maybe even create some at a high energy particle accelerator in the future.

 

[NGC 6712]

This doesn't really answer my question. I realize you can measure the effects. But, as was pointed out, if you don't know what the exotic dark matter is, the name doesn't really matter. You could call it Beauford for all the difference it makes. I suppose "dark" is an appropriate adjective, but maybe "matter" is not the appropriate descriptor.

I don't care what you call it, that's not my point. I'm curious what would need to happen to satisfy you that you know what it is. I'm suggesting that you would need the ability to produce the effect rather than just measure it. Is that part of it?

The name is immaterial though "dark matter" is fitting. It certainly is not visible and since we detect it through gravitational effects then matter is appropriate.

 

[Doveaman]

Well as you said, what we call it atm doesn't matter.

Then why didn't you leave it as "god did it"? At least we know God exist.

 

[Doveaman]

The name is immaterial though "dark matter" is fitting. It certainly is not visible and since we detect it through gravitational effects then matter is appropriate.

How do you know it's gravitational effects?

Gravitational effects is an assumption, not a fact.

Besides, gravitational effects was in doubt when the effects did not appear to behave like gravitational effects. That is until the dark god of the gaps was introduce to save the idea. And now you are searching desperately to find that elusive, invisible, dark god who sustains the galaxies.

 

[Doveaman]

Cool. It's always better to get the expert opinion.

He never said he was an expert. He said he work in it. People work in lots of areas, but they are not always experts in them.

 

[Nabobalis]

Then why didn't you leave it as "god did it"? At least we know God exist.

We can call it that if you want. The name dark matter stuck. I don't understand your obsession with the name.

We don't know that god exists, there happens to be a massive lack of evidence.

 

[NGC 6712]

How do you know it's gravitational effects?

Gravitational effects is an assumption, not a fact.

Besides, gravitational effects was in doubt when the effects did not appear to behave like gravitational effects. That is until the dark god of the gaps was introduce to save the idea. And now you are searching desperately to find that elusive, invisible, dark god who sustains the galaxies.

In what sense do you mean assumption? Is an apple falling from a tree and assumption too?

 

[Nabobalis]

In what sense do you mean assumption? Is an apple falling from a tree and assumption too?

He is a "plasma cosmologist", if you didn't know.

 

[Doveaman]

I don't care what you call it, that's not my point. I'm curious what would need to happen to satisfy you that you know what it is.

So am I.

I'm suggesting that you would need the ability to produce the effect rather than just measure it.

I think they call it the scientific method. But it's seldom used nowadays.

 

[NGC 6712]

He is also a "plasma cosmologist", if you didn't know.

Oh dearie me - I am sorry about that.

 

[Doveaman]

In what sense do you mean assumption? Is an apple falling from a tree and assumption too?

We have evidence of the presence of enough mass here on earth to cause an apple to fall.

We do not have evidence of the presence of enough mass in the galaxies to produce the rotation curves we see. Therefore gravity is assumed, and now you are trying to find enough mass to support your assumption. Big difference.

 

[Doveaman]

He is a "plasma cosmologist", if you didn't know.

I am??

You don't have to be a plasma cosmologist to see the weaknesses in an argument. You just need a brain.

 

[Nabobalis]

I am??

You don't have to be a plasma cosmologist to see the weaknesses in an argument. You just need a brain.

No, you need to believe that gravity doesn't work on large scales to make that argument.

 

[NGC 6712]

We have evidence of the presence of enough mass here on earth to cause an apple to fall.

We do not have evidence of the presence of enough mass in the galaxies to produce the rotation curves we see. Therefore gravity is assumed, and now you are trying to find enough mass to support your assumption. Big difference.

It's not just rotation curves by the way. Since gravity is the only long range force that can be acting on these length scales (it isn't em forces for instance) the assumption it is gravity is on a more sure footing than MOND for instance. And hypothesising dark matter is less of a reach than some new unknown force.

The rotation curves (plus other observed effects) are the evidence. Just like an apple falling is evidence.

 

[Doveaman]

the assumption it is gravity is on a more sure footing

I'm glad we agree it's an assumption. Now all you need to do is verify that assumption by providing us with the mass.

 

[Doveaman]

No, you need to believe that gravity doesn't work on large scales to make that argument.

You need to believe that gravity can work without mass to make your argument.

Show me the mass then you will have an reasonable argument. For now all you have is an unverified assumption.

Could it be gravity? Sure. But you will have to show us the mass and link that mass with the effects we see. So far you are in complete darkness.