What is dark matter, and anti matter? And how does it have an affect on our universe and its galaxies?

4 comments

My interest is in dark matter mostly and its affects on our universe aswell as the galaxies that float around in it. What its gravitational properties do to these objects and what not? And on anti matter i have very little understanding of that too. Thank you.

Comments:

Antimatter is matter that has equal mass and opposite charge to normal matter. If it comes into contact with normal matter it causes mutual annihilation. Examples of antimatter are positrons, anti protons, anti neutrons etc. Here is antimatter (positrons) coming off a block of Potassium as protons decay into neutrons.

As for dark matter.

Dark matter is matter we don’t understand and can’t see. It is speculated the vast majority of the universe is made of Dark matter, which remember is a generic term for any matter we can’t see. We know it exists by the gravitational influence it has on matter we can see. As for the galaxies, we have observed that galaxies rotate in a strange way, namely the stars on the outer arms of the spirals orbit the centre of the galaxy roughly as fast as the stars close to the centre. This is not how gravity is supposed to work. Look at our solar system Mercury orbits the Sun every 88 days or so, Earth every 365 days and Neptune every 185 Earth years. So we expect the stars in the outer reaches of the galaxy to take longer to complete their orbits than those close to the centre. Since this is not the case there must be a heck of a lot more matter in this and every other galaxy than we can see with our telescopes.

Just remember dark matter simply means “we don’t know the heck it is”, the same goes for dark energy and dark flow, these are just words to describe something astronomers have observed that cosmologists and theoretical physicists can’t yet explain.

{ 4 comments }

Jimmy

Dark matter and anti matter are two very different things.

Dark matter is matter that we have predicted must exist in the universe, but we can’t see it (yet). It has properties similar to matter (gravity etc)

Anti matter is made from the anti particles of normal properties, eg anti-protons, anti-electrons

Aditya Asopa

dark matter is a matter with yet unknown properties, can only be predicted by the gravity it exerts on other matter like galaxies. dark matter makes the angular momentum of galaxies different than former predictions.
while dark energy is responsible for speeding the inflation of universe.

antimatter is a form of matter made up of the antiparticles of the corresponding particles in the matter world.
like an atom of antihydrogen will have an antiproton in nucleus around which a positron is revoving.

there is very less observable antimatter in universe since when it gets in contact with matter it annihilates and pure energy in form of light is liberated.

DLM

Dark Matter, right now, is just the name we give to something we don’t really understand. There are places in the universe where we see the gravitational effects of a LOT of mass… the rotational curves of galaxies, gravitational lensing… but we do not see any actual matter there, in any wavelength of light. It’s almost as if something that behaves just like baryonic (normal) matter is present, that interacts with light and matter because of its gravity, but does not interact with light and matter in any other way.

Antimatter is identical to regular matter, but the charged subatomic particles are in reverse. An antiproton (- charge) resides in the nucleus while a positron ( + charge) is on the outside. When matter and antimatter come into contact, both are converted into electromagnetic energy. You’ve probably heard of a PET scan. The ‘P’ stadns for positron. I don’t know a lot about how positrons are stored, but I believe magnets are involved.

Sagim

Dark matter is still a mysterious substance. Theorists figure that in the universe’s infancy, dark matter served as a gravitational rallying point around which normal matter gathered.
Dark matter neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy. It is believed to constitute 83% of the matter in the universe.

The first person to provide evidence and infer the presence of dark matter was Swiss astrophysicist Fritz Zwicky, in 1933. He estimated the cluster’s total mass based on the motions of galaxies near its edge and compared that estimate to one based on the number of galaxies and total brightness of the cluster and found that there was about 400 times more estimated mass than was visually observable. The gravity of the visible galaxies in the cluster would be far too small for such fast orbits, so something extra was required. This is known as the “missing mass problem”.

Antimatter is a different thing altogether.
Antimatter is composed of antiparticles in the same way that normal matter is composed of particles. They may be produced in regions like the center of the Milky Way and other galaxies. Regions where very energetic celestial events takes place.
The presence of the resulting antimatter is detectable by the two gamma rays produced every time positrons annihilate with nearby matter.

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