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Albert Einstein even wrote a paper in 1939 claiming that stars could not collapse under gravity because matter could not be compressed beyond a certain point.
During most of the life of a normal star, over many billions of years, it will support itself against its own gravity by thermal pressure, caused by nuclear processes which convert hydrogen into helium.
Quasars are the brightest objects in the universe, and possibly the most distant detected so far. The name is short for ‘quasi-stellar radio sources’ and they are believed to be discs of matter swirling around black holes.
There is a black hole with a mass of about four million times that of the sun at the centre of our Milky Way galaxy.
In space, no one can hear you scream; and in a black hole, no one can see you disappear.
When a black hole is created by gravitational collapse, it rapidly settles down to a stationary state, which is characterized by only three parameters: the mass, the angular momentum (state of rotation) and the electric charge. Apart from these three properties, the black hole preserves no other details of the object that has collapsed.
The uncertainty principle of quantum mechanics implies that only particles with a wavelength smaller than that of the black hole itself could form a black hole. That means the range of potential wavelengths would be limited: it could not be infinite.
To my great surprise I found that the black hole seemed to emit particles at a steady rate.
These calculations were the first to show that a black hole need not be a one-way street to a dead end. Not surprisingly, the emissions suggested by the theory became known as Hawking Radiation.
According to some theories, the universe we experience is just a four-dimensional surface in a ten- or eleven-dimensional space.
