Black Holes Quotes

“There may in turn be a good deal of overlap between pure black hole research and the development of large-scale quantum computers, devices which will be of enormous benefit to our economy and the long-term future of our civilisation.”
― Brian Cox, Black Holes: The Key to Understanding the Universe

“An object flung upwards from the surface of the Earth must have a speed in excess of 11 kilometres per second to escape into deep space. This is known as Earth’s escape velocity. The gravitational pull at the Sun’s surface is much stronger, and the escape velocity is correspondingly higher at 620 kilometres per second. At the surface of a neutron star, the escape velocity can approach an appreciable fraction of the speed of light.‡ Laplace calculated that a body with a density comparable to the Earth but with a diameter 250 times larger than the Sun would have a gravitational pull so great that the escape velocity would exceed the speed of light, and therefore ‘the largest bodies in the Universe may thus be invisible by reason of their magnitude’.3”
― Brian Cox, Black Holes: The Key to Understanding the Universe

“It is an experimental fact that the passage of time varies from place to place and depends on how fast things move relative to each other. In a wonderfully simple experiment, carried out in 1971, Joseph C. Hafele and Richard E. Keating bought round-the-world airline tickets for themselves and four high-precision atomic clocks. In their own carefully chosen words: ‘In science, relevant experimental facts supersede theoretical arguments. In an attempt to throw some empirical light on the question of whether macroscopic clocks record time in accordance with the conventional interpretation of Einstein’s relativity theory, we flew four caesium beam atomic clocks around the world on commercial jet flights, first eastward, then westward. Then we compared the time they recorded during each trip with the corresponding time recorded by the reference atomic time scale at the US Naval Observatory. As was expected from theoretical predictions, the flying clocks lost time (aged slower) during the eastward trip and gained time (aged faster) during the westward trip.’16 The eastward clocks lost 59 nanoseconds and the westward clocks gained 273 nanoseconds.* These are tiny time differences over such a long journey, but they are not zero and, most importantly, the experimental observations agree with the mathematical calculations performed using Einstein’s theory. The Hafele–Keating paper finishes in a similarly concise fashion: ‘In any event, there seems to be little basis for further arguments about whether clocks will indicate the same time after a round trip, for we find that they do not.’ And there we have it – a remarkable and highly unexpected feature of our Universe that relativity theory is designed to describe: time is not what it seems.”
― Brian Cox, Black Holes: The Key to Understanding the Universe