So, it seems that Dark Matter now takes up most of space. What does that mean? What exactly is Dark Matter and why did we miss it before? How will change astronomy?
Educate me on this please.
Educate me on this please.
The second part of your question is kinda the answer to the first; dark matter is matter out there that we can't see, or haven't seen yet. We know it's out there because the movement of the matter we can see shows the presence of gravitational attraction from invisible sources. For example, the movement of most gallaxies shows that they have far more mass than is accounted for by the matter we can see. Also, some stars are seen to be orbitting around some invisible partner.Originally posted by Raven
What exactly is Dark Matter and why did we miss it before?
No, although most proposed forms of exotic matter would be considered dark matter, dark matter is not confined to those types of matter which would be called "exotic". Exotic matter would be forms of matter that are very unusual. Dark matter includes such things as planets, asteroids, black holes, cold dark dwarf stars, intersteller dust and gas clouds, and anything else that we can't see just by looking through a tellescope.Originally posted by maximus
i don't mean to hijack, but is dark matter the same thing as exotic matter?
Originally posted by ray b
OK here is a weird thought
we have matter and anti-matter, could there be a third type of "neutral matter" that doesnot interact with eathor normal matter or anti-matter but is made of quarks also???
could this stuff also account for the normal matter bias we "see" in the univerce now.
is there a anti-matter neutron?
how is it's in it's interactions with normal matter?? ie does a anti-neutron distroy a normal neutron like a postron-electron will act???
Although free neutrons have been observed, they probably don't exist in significant amounts in nature, because they only have a life of about 15 minutes on average. At least, I think it's about 15 minutes; it's really short, any rate.
btw are there free neutrons???
or can we even detect a free neutron??
how are they accounted for????
could there be massive amounts of free neutrons???
Yes, antimatter has been observed in the lab. One scientific use for it is being applied by researchers at CERN. Last September, they created a batch of anti-hydrogen (one positron orbiting one antiproton). This is a relatively stable form of antimatter that can be observed over time and studied. If these atoms behave as predicted, it will be a strong confirmation of the Standard Model.Originally posted by Raven
Call me ignorant (because I am or I wouldn't be asking this question), but what kind of proof do we have that anti-matter exist or is it just theory at this stage? If it does exist, what type of use can it be applied to in science?
is the fact that the large scale structures in the Universe don't fit our current model of gravity and matter. At the present time only one possible explaination has been proffered, that it concerns some sort of invisible matter. Other possibilites have simply not been considered.
This is not true. Milgrom has proposed a theory called MOND (modified Newtonian dynamics) which accounts for the galaxy motion problem without dark matter. It is somewhat ad hoc and difficult to test. It has been described in Scientific American tnis year.Other possibilites have simply not been considered.
I'll have to find that Sci Am article. Here's a good forum article with replies that I found.Originally posted by mathman
This is not true. Milgrom has proposed a theory called MOND (modified Newtonian dynamics) which accounts for the galaxy motion problem without dark matter. It is somewhat ad hoc and difficult to test. It has been described in Scientific American tnis year.