Gravitational Lensing and Dark Matter
September 5th 2010 05:38
Category: No Category
The purple colour on this Hubble image shows the distribution of dark matter within the cluster
The concept that light can bend or be bent has been around for two centuries.
It was Einstein who put it all together who postulated that light can bend when subjected to strong gravitational forces. The term used now is called gravitational lensing.
In 1979 a very distant quasar distorting light. What seemed somewhat bizarre is the that the quasar distorted the light of a nearby galaxy thereby producing two images.
By studying these cosmic mirages, cosmologists can learn much about the lensing process that effects objects in the foreground. The problem is not what we can see as visible light but what we can`t see referring to the dark matter that surrounds the object that is causing the distortion in the first instance.
The unseen dark matter makes up only 22 percent of matter. baryonic matter (matter made up of particles called baryons) baryonic matter is merely 4.5% of all matter The remaining 73%, they believe, is accounted for by the "dark energy". It’s the dark energy that's making the expansion of the universe speed up.
Not much is known about dark energy we know how much dark energy there is because we know how it affects the Universe's expansion. What we can see form observation on earth is only a very small percentage of what actually out there in the universe.
One explanation for dark energy is that it is a property of space. Space is not nothing. Space has amazing properties, many of which are just beginning to be understood.
There is another theory that dark energy is that it is a new kind of dynamical energy fluid or field, something that fills all of space but something whose effect on the expansion of the Universe is the opposite of that of matter and normal energy.
Some theorists have named this "quintessence," after the fifth element. In time the problem of understanding the property of dark matter will be solved. In the mean time we need to be like detectives find the clues analyze the facts.
Dark matter is an apt name because, it is dark, meaning that it is not visible form of energy that we can see unlike stars and planets that we can see.
image by NASA
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Comment by S.L.
The Political Brief
Concerning the bending of light... I understand that scientists can determine the presence of a planet orbiting a distant star because of the apparent "wobble" caused by gravity and light. Is it possible to determine the number of planets orbiting that star, or does the wobble just indicate presence and not number?
Comment by CarlCan
Astroearth
Camera Sense
Hi S.L.
Dark Matter is the matter that we can't see but we can detect the gravitational effects. We’re not sure what dark matter really is.
Dark matter has an important role in the structure and formation of galaxies, dark matter influences galaxy evolution.
Dark matter and Black holes are separate entities.
Black holes are stars that have collapsed but still have enormous mass their gravity is so intense that light cannot escape.
By measuring the star’s “wobble" on its axis it is possible to determine the presence of a planet or planets.
The number of planets may vary in proportion to the size of the star. It may mean that the star has just one giant planet perhaps the size of Jupiter Saturn and Uranus combined.
There is a giant planet orbiting star OGLE-TR-10. OGLE-TR-10 is a star located in the constellation of Sagittarius.
Stars with one one giant planet are common.
Comment by S.L.
The Political Brief
Comment by CarlCan
Astroearth
Camera Sense
The stars may not necessarily have a gas giants orbiting a star. Some stars can just one planet or many depending on the amount of material surrounding the star to form planetary bodies, the sizes vary. Some are large in size we, could have an earth size planet the size of Jupiter.
Some of these distant bodies orbit the star in reverse.