Topic: What is 'dark matter'?
wux's photo
Thu 01/13/11 05:00 PM


I was kinda wondering if perhaps our scientist missed something quite simple.

could it just be 'asteriod' fields...

Such small (relative) items would be nothing more than atomic dust at a range of a few astronomical units let alone at the range of lightyears...

and they would have (collectivly) mass and effect on nearby astronomical objects.

Yet be hard to 'see'.


The key property of dark matter is that it does not react to electromagnetic fields, hence the name "dark". All the items you listed react quite well with electromagnetic fields which would allow us to see them, hence they are not "dark".

Ha!

no photo
Thu 01/13/11 05:16 PM

Last I heard, we don't know with certainty what dark matter is. We are confident of its existence because of its effects, so talking about its effects is the best way to begin a conversation about why we think it exists and what it might be. "

So it's like the soul or like free will, you say?

These two have effects and scientists don't know what they are. Or sentences, or thoughts.



Can you itemize the 'effects' of the soul, or the 'effects' of free will?

Can you measure the effects of either?


What is the difference between two things that have effects, different effects, but neither are definable or even findable?


Who asserts that dark matter isn't findable?


Who is to say they are not the one and the same thing?


Who is to say that the universe wasn't farted out by a giant Aardvark with digestive problems? Proposing a idea and asking "who can disprove this?" is just silly.

Switching from "can you disprove this" to "is it reasonable to propose this", the answer is 'no'. Just because two 'things' are as yet undetectable is no cause to think they are the same thing.

wux's photo
Thu 01/13/11 05:31 PM
Edited by wux on Thu 01/13/11 05:32 PM


Last I heard, we don't know with certainty what dark matter is. We are confident of its existence because of its effects, so talking about its effects is the best way to begin a conversation about why we think it exists and what it might be. "

So it's like the soul or like free will, you say?

These two have effects and scientists don't know what they are. Or sentences, or thoughts.



Can you itemize the 'effects' of the soul, or the 'effects' of free will?

Can you measure the effects of either?


What is the difference between two things that have effects, different effects, but neither are definable or even findable?


Who asserts that dark matter isn't findable?


Who is to say they are not the one and the same thing?


Who is to say that the universe wasn't farted out by a giant Aardvark with digestive problems? Proposing a idea and asking "who can disprove this?" is just silly.

Switching from "can you disprove this" to "is it reasonable to propose this", the answer is 'no'. Just because two 'things' are as yet undetectable is no cause to think they are the same thing.



I concede to your last point.

Dark matter is not findable. Its location is known, but we don't know what it is, and if you don't know what something is, it hasn't been found. Once you found it, you know what it is. Knowing a few of its effects is not the same thing as having found it. Like the North Pole. We only know what it is and where it is located after Peery found it. I am joking here, but only in the last three sentences, including this one, concluding with this one.

Soul? Free will? One effect (undeniable) is the impression on human thought that they exist. Soul has another effect, which science can't explain, and that is conscience, or self-awareness, and its derivatives, such as feelings and desires and pain and pleasure. Sure there is nerve impulses, but there is no scientific explanation why a nerve impulse of sorts ought to make us feel hungry or sexy. A third effect of soul is the need to conduct double-blind experiments not only on human subjects, but on mice and giraffes and other living things as well. This is known, and scientists stand by this effect. If you ask them how is it possible, the need to conduct double-blind experiments on earth worms, they say "science can't answer it." True.

AdventureBegins's photo
Thu 01/13/11 06:51 PM


That dot there... toward the right of centre, a small but visible dot... shouldn't there be a sign, "you are here"?

And... erm... is this picture showing the space we know of that is seven angstroms in diameter, or sixty-five billion light years across?

Which way is north? Or "up"? What's the red light for? A "yahoo" map, showing the best way to drive from here to there?

As a picture, it is beautiful. To me it looks like Winnie-the-Pooh, sitting at the moment on a tree-trunk in front of his house that has a sign above his door, "John Smith", and on his left hand, at hip hight, is another, smaller version of him. As drawn by Uncle Sheppard, not by Walt Disney.


Having the technology to produce such a model I know that the model only works when the proper 'assumptions' are fiddled into the formulas...

Without the 'asumptions' you get static.

AdventureBegins's photo
Thu 01/13/11 06:59 PM



I was kinda wondering if perhaps our scientist missed something quite simple.

could it just be 'asteriod' fields...

Such small (relative) items would be nothing more than atomic dust at a range of a few astronomical units let alone at the range of lightyears...

and they would have (collectivly) mass and effect on nearby astronomical objects.

Yet be hard to 'see'.


The key property of dark matter is that it does not react to electromagnetic fields, hence the name "dark". All the items you listed react quite well with electromagnetic fields which would allow us to see them, hence they are not "dark".

Ha!

un ha!... PLANETS interact quite well with electromagnetic fields yet we see them not (with but a few exceptions that we 'see' by extrapolating their trajectories based opon gravational disturbance of their primary).

Even a planet many, many times the size of Jupiter we can only see mathmatically for the most part (by gravity calculations - not by EM interactions)...

ergo... How do we know an object less than 30 meters in size is there. Gravity of a single such object is not large enough to be measured (by our limited knowledge) at ranges of lightyears... However the combined gravitational effect of a large field of such small objects would have a measurable effect.

metalwing's photo
Thu 01/13/11 07:29 PM




I was kinda wondering if perhaps our scientist missed something quite simple.

could it just be 'asteriod' fields...

Such small (relative) items would be nothing more than atomic dust at a range of a few astronomical units let alone at the range of lightyears...

and they would have (collectivly) mass and effect on nearby astronomical objects.

Yet be hard to 'see'.


The key property of dark matter is that it does not react to electromagnetic fields, hence the name "dark". All the items you listed react quite well with electromagnetic fields which would allow us to see them, hence they are not "dark".

Ha!

un ha!... PLANETS interact quite well with electromagnetic fields yet we see them not (with but a few exceptions that we 'see' by extrapolating their trajectories based opon gravational disturbance of their primary).

Even a planet many, many times the size of Jupiter we can only see mathmatically for the most part (by gravity calculations - not by EM interactions)...

ergo... How do we know an object less than 30 meters in size is there. Gravity of a single such object is not large enough to be measured (by our limited knowledge) at ranges of lightyears... However the combined gravitational effect of a large field of such small objects would have a measurable effect.


I'm sorry that you don't understand but matter as we know it absorbs electromagnetic radiation and we have the instruments to detect it. Dark matter does not. It really is that simple.

Your description is nonsense. We can and do "see" dust in distant galaxies. We can't "see" dark matter around our own galaxy, but we can detect by the methods described above. You either understand the absorption of electromagnetic radiation or you don't.

mightymoe's photo
Thu 01/13/11 07:35 PM
we don't see electromagnetic fields, we just see the effects from them...

Jtevans's photo
Thu 01/13/11 07:51 PM
i don't know what dark matter is but it grows in the back of me fridge.i tried poking it with a knife once...........i'm still unable to retrieve the knife ohwell

metalwing's photo
Thu 01/13/11 07:53 PM

we don't see electromagnetic fields, we just see the effects from them...


The effect of electromagnet fields is electromagnet radiation which is what we detect. Matter is made of particles that have electromagnetic fields (electrons and protons) and their fields are disturbed by the radiation passing through space causing them to absorb and re-radiate radiation of different frequencies.

Dark matter does not.

AdventureBegins's photo
Thu 01/13/11 08:21 PM


we don't see electromagnetic fields, we just see the effects from them...


The effect of electromagnet fields is electromagnet radiation which is what we detect. Matter is made of particles that have electromagnetic fields (electrons and protons) and their fields are disturbed by the radiation passing through space causing them to absorb and re-radiate radiation of different frequencies.

Dark matter does not.

Aye... Obviously neither do 'asteriods' as it seems hard to 'detect' even the ones in our near space environment till they 'occlude' something or someone happens to point a telescope directly at one...

Given the distance involved it would be astronomical (pardon the pun) to expect us to actually 'see' even a massive field of the darn things.

Yet given the number of such 'objects' in our near space environment it just might be that hundreds of billions of them exist just between us and a star merely 9 Light Years away. And we would see them not.

mightymoe's photo
Thu 01/13/11 08:44 PM



we don't see electromagnetic fields, we just see the effects from them...


The effect of electromagnet fields is electromagnet radiation which is what we detect. Matter is made of particles that have electromagnetic fields (electrons and protons) and their fields are disturbed by the radiation passing through space causing them to absorb and re-radiate radiation of different frequencies.

Dark matter does not.

Aye... Obviously neither do 'asteriods' as it seems hard to 'detect' even the ones in our near space environment till they 'occlude' something or someone happens to point a telescope directly at one...

Given the distance involved it would be astronomical (pardon the pun) to expect us to actually 'see' even a massive field of the darn things.

Yet given the number of such 'objects' in our near space environment it just might be that hundreds of billions of them exist just between us and a star merely 9 Light Years away. And we would see them not.


we can't even see planets, much less an asteriod

metalwing's photo
Thu 01/13/11 08:49 PM




we don't see electromagnetic fields, we just see the effects from them...


The effect of electromagnet fields is electromagnet radiation which is what we detect. Matter is made of particles that have electromagnetic fields (electrons and protons) and their fields are disturbed by the radiation passing through space causing them to absorb and re-radiate radiation of different frequencies.

Dark matter does not.

Aye... Obviously neither do 'asteriods' as it seems hard to 'detect' even the ones in our near space environment till they 'occlude' something or someone happens to point a telescope directly at one...

Given the distance involved it would be astronomical (pardon the pun) to expect us to actually 'see' even a massive field of the darn things.

Yet given the number of such 'objects' in our near space environment it just might be that hundreds of billions of them exist just between us and a star merely 9 Light Years away. And we would see them not.


we can't even see planets, much less an asteriod


That's not the same problem. Planets are close to stars that overwhelm the light from the planet. However, we can detect the planets by their gravitational effects just like dark matter.

We can see dust in far smaller amounts at far greater distances than the same amount of dark matter nearby. In fact we can not see huge amounts of dark matter nearby.

rlynne's photo
Thu 01/13/11 09:05 PM
Edited by rlynne on Thu 01/13/11 09:07 PM
metalwing- so on the pie chart what do you consider "dark energy" comparatively, how is that defined?

and wux...as for understanding the effects of thoughts/souls as being interpreted as energy or dark matter...I suggest picking up a book by lyn buchanan The Seventh Sense...if nothing else for you its an interesting read

AdventureBegins's photo
Thu 01/13/11 09:17 PM





we don't see electromagnetic fields, we just see the effects from them...


The effect of electromagnet fields is electromagnet radiation which is what we detect. Matter is made of particles that have electromagnetic fields (electrons and protons) and their fields are disturbed by the radiation passing through space causing them to absorb and re-radiate radiation of different frequencies.

Dark matter does not.

Aye... Obviously neither do 'asteriods' as it seems hard to 'detect' even the ones in our near space environment till they 'occlude' something or someone happens to point a telescope directly at one...

Given the distance involved it would be astronomical (pardon the pun) to expect us to actually 'see' even a massive field of the darn things.

Yet given the number of such 'objects' in our near space environment it just might be that hundreds of billions of them exist just between us and a star merely 9 Light Years away. And we would see them not.


we can't even see planets, much less an asteriod


That's not the same problem. Planets are close to stars that overwhelm the light from the planet. However, we can detect the planets by their gravitational effects just like dark matter.

We can see dust in far smaller amounts at far greater distances than the same amount of dark matter nearby. In fact we can not see huge amounts of dark matter nearby.

Define 'dust' in interstellar terms please.

The photographs and other such items I have looked at describe fields of 'gasses' and such which they label as dust.

None however purports to actually show 'particles' of actual physical dust (as in chunks of rock).

A field of asteriods at that range would also be 'overwhelmed' by the local stars output.

no photo
Thu 01/13/11 10:21 PM
Dark matter is not findable. Its location is known, but we don't know what it is, and if you don't know what something is, it hasn't been found.


To me, 'findable' means 'able to be found'. That something has not yet been found is not evidence that it cannot eventually be found.

There might be some reason (unknown to me) to believe that we will never learn the true identity and nature of dark matter, and that's where I was leading with my question "who asserts that dark matter [cannot be found]".

From the information available to me, I would agree that 'dark matter hasn't been found', and that 'its unknown whether it might ever be found' (ie findable).

I am joking here, but only in the last three sentences, including this one, concluding with this one.


Please don't take offense, but I think you are joking most of the time.


Soul? Free will? One effect (undeniable) is the impression on human thought that they exist. Soul has another effect, which science can't explain, and that is conscience, or self-awareness, and its derivatives, such as feelings and desires and pain and pleasure. Sure there is nerve impulses, but there is no scientific explanation why a nerve impulse of sorts ought to make us feel hungry or sexy. A third effect of soul is the need to conduct double-blind experiments ...


My purpose in asking the 'known effects of the soul' was to compare them with the 'known effects of dark matter' to eventually illustrate that there is no cause to believe that they might be the same thing (while acknowledging I can't prove they aren't). Since we've already reached that point of agreement....thank you for sharing your thoughts on the soul and free will.


no photo
Thu 01/13/11 10:22 PM

and wux...as for understanding the effects of thoughts/souls as being interpreted as energy or dark matter...I suggest picking up a book by lyn buchanan The Seventh Sense...if nothing else for you its an interesting read


Oh no! Did someone actually publish a book - that is actually being purchased by people - that makes the case that human souls are dark matter????

no photo
Thu 01/13/11 10:28 PM
My understanding is that: we know that dark matter isn't 'planets, asteroids, dust, etc' because we know something about the relationship between the total mass of a collection of such bodies and the way that collection of bodies would interact with light, if it existed as normal matter.

If all the mass which we infer to exist as dark matter were actually in the form of planets, asteroids, and dust, then we would see the additional effects of that matter in ways which we don't see additional effects of dark matter.

I'll try to give some examples, but these might be misleading as its been many years since I studied this: If it were to exist as gas, we would see absorption and emission spectra for that gas. As dust, we would see the intensity of light that passes through the dust being diminished in a predictable way (and we know the expected intensity of the source by our knowledge of stars in general, types, sizes, stages of life, luminosity).


no photo
Thu 01/13/11 10:32 PM

we don't see electromagnetic fields, we just see the effects from them...


We don't see the effects of electromagnetic fields, we just see the effects of the effects.


I mean, we don't see the effects of the effects of the electromagnetic fields, we just see the effects of the effects of the effects.

You could break it down into a dozen or more steps of interactions from some external e/m field interaction and the 'perception' of its existence within our brain.


Everything that we believe to exist, we believe to exist because of its effects - not through any 'direct perception'. Even the firing of your optic nerve is an 'effect'.

This is why its not unreasonable to assert the existence of dark matter, though we know so little about it.

no photo
Thu 01/13/11 10:34 PM

Aye... Obviously neither do 'asteriods' as it seems hard to 'detect' even the ones in our near space environment till they 'occlude' something or someone happens to point a telescope directly at one...

Given the distance involved it would be astronomical (pardon the pun) to expect us to actually 'see' even a massive field of the darn things.

Yet given the number of such 'objects' in our near space environment it just might be that hundreds of billions of them exist just between us and a star merely 9 Light Years away. And we would see them not.


Its hard to detect one asteroid. It would be impossible to miss the effects of a quantity of asteroids necessary to account for the mass of dark matter.

no photo
Thu 01/13/11 10:37 PM

we can't even see planets, much less an asteriod


Its not accurate to generalize our ability to see (or not) these objects - it depends on their size and their location. Last I hear, can certainly see some planets in other systems.

Many individual planets might be impossible for us to see, at their actual sizes and locations...but as I mention above, if there were enough of them to account for dark matter mass, there presence would be known.