Work and World

A Brief History Of Everything, Feat. Neil DeGrasse Tyson

“The world has persisted
many a long year, having once been set going
in the appropriate motions. From these, everything else follows.” Lucretius. In the beginning, about 13.7 billion years ago, all the space, and all the matter,
and all the energy of the known universe was contained in a volume less
than one trillionth the size of the point of a pin. Conditions were so hot the
basic forces of nature that collectively describe
the universe were unified. For reasons unknown, this
sub-pinpoint-sized cosmos began to expand. When the universe was a piping-hot
10 to the 30th degrees, and a youthful 10 to the
minus 43 seconds old — before which all of our
theories of matter and space break down and have no meaning — black holes spontaneously formed,
disappeared, and formed again, out of the energy contained
within the unified field. Under these extreme conditions,
in what is admittedly speculative physics, the structure of space and
time became severely curved as it gurgled, into a spongy,
foamlike form. During these epochs, phenomena described by
Einstein’s general theory of relativity, the modern theory of gravity, and quantum mechanics, the description
of matter in its smallest scales, were indistinguishable from one another. As the universe continued
to expand and cool, gravity split from the other forces. Quickly thereafter, the strong nuclear force and
the electroweak force split from each other, which was accompanied by an
enormous release of stored energy, that induced a rapid 30-power-of-10
increase in the size of the universe. The rapid expansion of the universe,
known as the epoch of inflation, stretched and smoothed out the cosmic
distribution of matter and energy, so that any regional
variation in density became less than one part
in one hundred thousand. Continuing onward with what is
now laboratory confirmed physics, the universe was hot enough for photons
to spontaneously convert their energy into matter-antimatter particle pairs, which immediately thereafter
annihilated each other, returning their energy
back to the photons. For reasons unknown, this symmetry between
matter and antimatter had been broken, which led to a slight excess
of matter over antimatter. For every billion antimatter particles, a billion plus one matter
particles were born. This asymmetry was small,
but really, really important for the future evolution
of the universe. As the universe continued to cool,
the electroweak force split into the electromagnetic force
and the weak nuclear force, completing the four distinct
and familiar forces of nature. While the energy of the photon
bath continued to drop, pairs of matter-antimatter particles
could no longer be created spontaneously from the available photons. All remaining pairs of matter-antimatter
particles swiftly annihilated, leaving behind a universe with
one particle of ordinary matter for every billion photons,
and no antimatter. Had this matter-over-antimatter
asymmetry not emerged, the expanding universe would forever
be composed of light an nothing else, not even astrophysicists. Over a roughly three-minute period, protons and neutrons assembled
from the annihilations to become the simplest atomic nuclei. Meanwhile, free-roving electrons thoroughly
scattered the photons to and fro, creating an opaque soup
of matter and energy. When the univers cooled below
a few thousand degrees Kelvin, about the temperature
of fireplace embers, the loose electrons moved slowly enough to get snatched from the
soup by the roving nuclei, to make completed atoms of
hydrogen, helium, and lithium, the three lightest elements. The universe is now, for the first time,
transparent to visible light, and these free-flying
photons are visible today as the cosmic microwave background. Over the first billion years, the universe continued
to expand and cool, as matter gravitated into this massive
concentrations we call galaxies. Between 50 and 100
billion of them formed, each containing hundreds
of billions of stars, that undergo thermonuclear
fusion in their cores. Those stars with more than about
10 times the mass of the Sun achieve sufficient pressure
and temperature in their cores to manufacture dozens of
elements heavier than hydrogen, including elements that compose
the planets and life upon them. These element would be
emarassingly useless were they to remain
locked inside the star. But high mass stars,
fortuitously, explode, scattering their chemically enriched
guts throughout the galaxy. After seven or eight billion
years of such enrichment, an undistinguished star was born
in an undistinguished region of an undistinguished galaxy, in an undistinguished
part of the universe: the outskirts of the Virgo supercluster. During the formation
of this star system, matter condensed and accreted out of the
parent cloud of gas while circling the Sun. The gas cloud from which the Sun formed contained a sufficient
supply of heavy elements to form a system of planets, thousands
of asteroids, and billions of comets. For several hundred million years,
the persisting impacts of high velocity comets
and other leftover debris, rendered molten the surfaces
of the rocky planets, preventing the formation
of complex molecules. As less an less accretable matter
remained in the Solar System, the planet surfaces began to cool. The one we call Earth formed
in a zone around the Sun where oceans remain
largely liquid in form. Had Earth been much closer to the Sun,
the oceans would have vaporized. Had Earth been much farther,
the oceans would have frozen. In either case, life as we know
it would not have evolved. Within the chemically rich liquid
oceans, by a mechanism unknown, there emerged simple anaerobic
bacteria, that unwillingly transformed Earth’s carbon
dioxide rich atmosphere into one with sufficient oxygen to
allow aerobic organisms to emerge and dominate the oceans and land. The same oxygen atoms,
normally found in pairs, O2, also combined in threes to form ozone,
O3, in the upper atmosphere, that protects Earth’s surface from most of the Sun’s molecule-hostile
ultraviolet photons. The remarkable diversity
of life on Earth and we presume elsewhere
in the universe, is owed to the cosmic
abundance of carbon, and the countless number of molecules,
simple and complex, made from it. How can you argue, when there are more
varieties of carbon-based molecules than all other molecules combined? But life is fragile. Earth’s encounters with large leftover
meteors, a formerly common event, wreak intermittent havoc
upon the ecosystem. A mere 65 million years ago,
less than 2% of Earth’s past, a ten trillion ton asteroid hit
what is now the Yucatan peninsula, and obliterated over 70% of Earth’s
species of flora and fauna, including dinosaurs,
the dominant land animals. This ecological tragedy
pried open an opportunity for small surviving mammals to
fill freshly vacant niches. One big-brained branch of these mammals,
that which we call primates, evolved a genus and a
species, homo sapiens, to a level of intelligence
that enabled them to invent methods and tools of
science, to invent astrophysics, and to deduce the origin and
evolution of the universe. Yes, the universe had a beginning. Yes, the universe continues to evolve. And yes, every one of our
bodies atoms is traceable to the Big Bang and to the thermonuclear
furnace within high mass stars. We are not simply in the
universe, we are part of it. We are born from it. One might even say, we’ve been empowered
by the universe to figure itself out. And we’ve only just begun. I’m Neil deGrasse Tyson, astrophysicist and the
Frederick P. Rose Director of New York City’s Hayden Planetarium. Keep looking up.
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