The Naked Scientists

The Naked Scientists Forum

Author Topic: If it's Dark Mater, Flush it Down  (Read 2020 times)

Offline Dave Thacker

  • Jr. Member
  • **
  • Posts: 10
    • View Profile
If it's Dark Mater, Flush it Down
« on: 04/08/2013 13:22:33 »
Below is an excerpt from my blog site.   I certainly am not claiming to have knowledge in this area.  However, the concept of "Dark Mater" has always set off my stink-o-meter as utter nonsense.   Understand, I'm not campaigning against the concept.  Just wondering if it could be utter nonsense or is it a fine cheese I haven't learned enough about to appreciate the aroma just yet?  So, on to the excerpt.....

"Why does this theory sound silly? Simple, we have samples of the Moon, Mars, Comets, Asteroids and etc. We have the entire earth, we’ve been in space for a very long time gathering information and materials to study (think of the money that is costing) and you’re telling me we've not been lucky enough to come across a material that science theorizes makes up 80% of the universe? Holly sh1t Batman! How could we be so unlucky? It’s like saying there is a society on the earth that has never discovered water. It’s silly that something so common should be so hard to find. Perhaps if we keep funding the study and they look long enough they’ll find the Dark Matter. It’s obvious isn't it?"

See my entire past insane mumbling about dark mater here: newbielink:http://www.radicalrc.com/blog/?p=1856 [nonactive]

Can the Naked Scientists resolve this simple riddle for me?  How can we not have a sample of something making up 80% of the galaxy's material?  How could it be so rare?
« Last Edit: 04/08/2013 13:28:48 by Dave Thacker »


 

Offline Pmb

  • Neilep Level Member
  • ******
  • Posts: 1838
  • Physicist
    • View Profile
    • New England Science Constortium
Re: If it's Dark Mater, Flush it Down
« Reply #1 on: 04/08/2013 14:23:17 »
Quote from: Dave Thacker
"Why does this theory sound silly? Simple, we have samples of the Moon, Mars, Comets, Asteroids and etc. We have the entire earth, we've been in space for a very long time gathering information and materials to study (think of the money that is costing) and you’re telling me we've not been lucky enough to come across a material that science theorizes makes up 80% of the universe? Holly sh1t Batman! How could we be so unlucky?
It’s not bad luck at all. One possible candidate for dark matter are black holes. We’ve already discovered their existence. Since they can’t be observed directly it makes sense that they’d be dark matter. Another candidate is a hypothetical particles called WIMPs  which stands for Weakly Interacting Massive Particle which means that it only interacts via the gravitational interaction. We’d have no way to observe them other than from their gravitational effects. If they exist then their mass is small enough only to be observed on a galactic scale hence as dark matter.

So it’s very far from the truth to think that because they’re so abundant that they’d be easy to detect.

See http://en.wikipedia.org/wiki/Dark_matter
 

Offline Dave Thacker

  • Jr. Member
  • **
  • Posts: 10
    • View Profile
Re: If it's Dark Mater, Flush it Down
« Reply #2 on: 04/08/2013 20:08:50 »
Thank you for your reply.  The Wiki page was quite a read.  Are there examples of other "materials" which exist in significant quantities for which we have no sample?

Dave
 

Offline Pmb

  • Neilep Level Member
  • ******
  • Posts: 1838
  • Physicist
    • View Profile
    • New England Science Constortium
Re: If it's Dark Mater, Flush it Down
« Reply #3 on: 04/08/2013 21:11:31 »
Thank you for your reply.  The Wiki page was quite a read.  Are there examples of other "materials" which exist in significant quantities for which we have no sample?

Dave
You're most welcome. Welcome to the forum by the way!

There's something called Dark Energy which shouldn't be confused with dark matter. Dark energy is what is making the universe expand at an accelerating rate. This is the closest we've come to antigravity! I can really be called is antigravity because its gravitational repulsion. There are also things called virtual particles. Whether they really exist or not is a weird question. They can't be observed, even in principle. So I'm not sure they can be said to exist.

There are also things never seen before like cosmic strings and vacuum domain walls but have been postulated to exist. Look them up using Google and see what you can find on them. If you have any questions then please feel free to ask. - Pete
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4123
  • Thanked: 245 times
    • View Profile
Re: If it's Dark Mater, Flush it Down
« Reply #4 on: 04/08/2013 22:27:33 »
The atomic nucleus makes up about 99.9% of visible matter  in our solar system, but there was no direct evidence for it before Rutherford's experiment in 1911.

Space is filled with cosmic rays, but their nature was not really discovered until the 1930s. We still don't really know where they come from (ie there are several competing theories).

It is believed that space is filled with gravitational waves, but no direct detection has been achieved (so far).

Just this year, a particle was discovered which was composed of 4 quarks. This is not the last such discovery expected in particle physics - the LHC will reopen in a year or two with increased power, which is expected to reveal previously unseen effects.
« Last Edit: 04/08/2013 22:51:44 by evan_au »
 

Offline Pmb

  • Neilep Level Member
  • ******
  • Posts: 1838
  • Physicist
    • View Profile
    • New England Science Constortium
Re: If it's Dark Mater, Flush it Down
« Reply #5 on: 05/08/2013 01:31:34 »
Also it's impossible to observer single quarks. They always appear in multiples greater than one, i.e. as parts of a hadron (i.e. as either a baryon or a meson).
 

Offline Dave Thacker

  • Jr. Member
  • **
  • Posts: 10
    • View Profile
Re: If it's Dark Mater, Flush it Down
« Reply #6 on: 06/08/2013 03:00:26 »
I appreciate all the reply's and positive response to my question.  I would say certainly, I'm less skeptical and have a little direction for further reading on the subject.

I can extend my question further.   That would be, why does it mater?  Setting aside just wanting to know or verify other theories, is there a practical application to answering the question?  In other words, are there theorized benefits to people like promises of faster computers, cheaper energy or touch-less can openers?

Again, thanks for entertaining my question.  I have a few more to stick up.   I'll try to come up with some hard ones.  ;-)

Dave
« Last Edit: 06/08/2013 03:03:42 by Dave Thacker »
 

Offline Pmb

  • Neilep Level Member
  • ******
  • Posts: 1838
  • Physicist
    • View Profile
    • New England Science Constortium
Re: If it's Dark Mater, Flush it Down
« Reply #7 on: 06/08/2013 10:48:03 »
Quote from: Dave Thacker
Setting aside just wanting to know or verify other theories, is there a practical application to answering the question?  In other words, are there theorized benefits to people like promises of faster computers, cheaper energy or touch-less can openers?
The thing about science is that you can never predict in advance how scientific advances will benefit society. When I first learned about computers in the 70's I had no idea they'd be in nearly ever home in America by the 21st century and be used nby children to surf the interenet.
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4123
  • Thanked: 245 times
    • View Profile
Re: If it's Dark Mater, Flush it Down
« Reply #8 on: 06/08/2013 11:37:00 »
Dr Karl imagined a mother in 100 years saying "Johnny, stop playing with the Dark Matter, and come inside - your dinner is ready!".

But seriously, at present we don't know what it is, we can't see it and we can't manipulate it, so the rest is pure speculation for now.
 

Offline JP

  • Neilep Level Member
  • ******
  • Posts: 3366
  • Thanked: 2 times
    • View Profile
Re: If it's Dark Mater, Flush it Down
« Reply #9 on: 06/08/2013 14:37:57 »
Just to add to what's been said, what we really know about dark energy is that our observations (particularly of the rotation of galaxies) doesn't match our current theories of gravity if all we do is plug in the matter we see.  This has been confirmed with multiple independent observations, so there's not a lot of doubt that these observations are valid.

As with anything in science, as soon as a theory fails, scientists look for explanations.  One option is that the theory is correct, but that part of the matter is invisible to telescopes.  Another option is that our theory of gravity has an error and needs to be amended. 

Scientists always go with evidence in the end, but along the way they have to come up with hypotheses and test them, so there's a lot of work being done in both areas to come up with testable hypotheses.  Of course, in deciding where to spend resources (intellectual and financial), scientists have to make an educated guess as to which explanation is more likely.  Most choose that there's matter that can't be seen with telescopes.  Why?

Well, we know that our theories of gravity work exceptionally well for many other things, so if we have to fix them, it's a peculiar fix that only occurs in certain circumstances.  The fix would also behave suspiciously like more matter--and coincidences like that are rare in science.  However, this is still a possibility and there are reputable scientists looking into it. 

Moreover, we know there are types of matter that would be invisible to telescopes, and we've detected some of them already.  Pmb mentioned them, but an extremely common form of such matter is neutrinos.  We create these in particle colliders and there is a vast number created by the sun.  But they interact so weakly with other matter that detecting them is exceptionally rare.  They would be essentially invisible to telescopes.  Neutrinos we've seen don't have all the properties needed for dark matter (they move too fast), but the fact that we know of a very common particle that is invisible to telescopes makes it very plausible there are others.
 

The Naked Scientists Forum

Re: If it's Dark Mater, Flush it Down
« Reply #9 on: 06/08/2013 14:37:57 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums
 
Login
Login with username, password and session length