These are excerpts and elaborations from my book "The Nature of Consciousness"
Relativistic
Cosmology Einstein’s equations described more than
just the interaction between two bodies (like Newton’s gravitational equations did):
they described the very story of the universe. One could play that film
backwards or forward, and derive how the universe used to be or what it will be
like. Einstein briefly toyed with the idea of a “cosmological constant”. He was
not happy to discover that his equations predicted a universe in continuous
turmoil (and most likely doomed to collapse under the effect of gravitation),
so he introduced a constant in his equations to counterbalance gravitation
(basically, a sort of “anti-gravity”)and make the universe static. When in 1929
Edwin Hubble showed that the universe is expanding,
Einstein realized that the turmoil was real and decided that there was no need
for his cosmological constant. Density of mass
plays a crucial role in Einstein’s equations: the denser the
mass, the bigger the warp it causes to space-time, the stronger the
gravitational effect felt by nearby matter. Thus collapsing stars are
particularly relevant objects in Einstein’s universe. In 1967, the first
“pulsar” was observed: a rapidly-spinning collapsed star. Shortly after
Einstein published his gravitational field equation,
in 1916 the German physicist Karl Schwarzschild found a solution that determines the gravitational field for any
object, given its mass and its size. That solution goes to infinity for a
specific ratio between mass and size: basically, if the object is dense enough
(lots of mass in a tiny size), the gravitational attraction it generates is
infinite. Nothing, not even light, can escape this object, which was therefore
named "black hole" (by John Wheeler). And everything that gets near
it is doomed to fall into it, and be trapped in it forever. Schwarzschild considered a mass that was spherical with perfect symmetry. Later, the US physicist Martin Kruskal ("Maximal Extension of Schwarzschild Metric", 1960) expanded Schwarzchild's black solution to all domains of space and time. That “maximally extended Schwarzschild solution” turned out to be four possible solutions, each one mathematically legitimate: a black hole, a “white hole”, and two universes connected at their horizons by a wormhole. A black hole swallows everything and nothing can escape from it, whereas a white hole spits out everything and nothing can enter it. They look like time-reversed copies of each other. Back to the beginning of the chapter "The New Physics" | Back to the index of all chapters |
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