Big Bang—1 January, 12:00 midnight
In its beginning, everything was a single point. This cosmic womb nurtured everything before it came to be. Every star; every planet; every flower; every lion, tiger, or bear; every Mozart, Einstein, or Madonna; every banana split, parfait, or brownie à la mode; every Illiad, I-Ching, or Bible; every hatred, joy, or love; every thing lay dormant within this primordial point. This is the story of how that point became our world, became us. This is our story.
According to current theory, all of what currently makes up the universe was packed into a space no larger than an atom. It doesn’t make sense to ask what was outside that point because even space was curled up inside this cosmic egg. It’s kind of like asking what’s north of the North Pole. Nor does it make sense to ask what happened before the point began to expand billions of years ago because time began its flow with the expansion. Our universe began in the in what is known as the Big Bang.
There was neither non-existence nor existence then. There was neither the realm of space nor the sky which is beyond. What stirred? Where? In whose protection? Was there water, bottlemlessly deep?
There was neither death nor immortality then. There was no distinguishing sign of night nor of day. That One breathed, windless, by its own impulse. Other than that there was nothing beyond.
Darkness was hidden by darkness in the beginning, with no distinguishing sign, all this was water. The life force that was covered with emptiness, that One arose through the power of heat.
Desire came upon that One in the beginning, that was the first seed of mind. Poets seeking in their heart with wisdom found the bond of existence and non-existence.
Their cord was extended across. Was there below? Was there above? There were seed-placers, there were powers. There was impulse beneath, there was giving forth above.
Who really knows? Who will here proclaim it? Whence was it produced? Whence is this creation? The gods came afterwards, with the creation of this universe. Who then knows whence it has arisen?
Whence this creation has arisen—perhaps it formed itself, or perhaps it did not â€“ the One who looks down on it, in the highest heaven, only He knows or perhaps He does not know. (Nāsadīya Sukta, Rigveda)
Planck Epoch: We really don’t know what was happening in the first instant of the Big Bang 13,700 million years ago (Mya). The laws of physics as we know them break down during the Planck Epoch, the first 10-43 seconds after the Big Bang.1 This notation means one tenth multiplied by itself 43 times, or put another way, 0.000 000 000 000 000 000 000 000 000 000 000 000 000 000 1, an extremely, extremely small number. According to one theory, the universe was about 10-35 meters across.2 Because all of the matter and energy of the universe were packed into such a small space, it was also ludicrously hot: 1032 degrees Celsius. This notation means 10 multiplied by itself 32 times, or 100 000 000 000 000 000 000 000 000 000 000.3
It is impossible to fully comprehend how extremely small the universe was. To try, imagine a young child about one meter tall who holds in their cupped hand a sphere that is 10-35 meters across. Actually, the sphere is so small that the child’s hand would appear empty. Now, stretch the child and the sphere until the child is as tall as the diameter of the universe that we can currently see. Light travels very fast—186,000 miles per second—but it would take 93 billion years for light to travel from the child’s head to its foot. The sphere has stretched too, but if we were cradled in the child’s gigantic hand, the expanded sphere would still be too small for us to see. It would still only be a few atoms wide. This is unimaginably small.
Just as the universe was incomprehensibly small, the temperature was incomprehensibly large. For comparison, the core of our sun is only 107 degrees Celsius (i.e. 10,000,000 degrees). Multiply the heat of the sun by ten million. Hellish, we might be tempted to call it. Now multiply that hellish temperature by another million. And do it again. And again. And again. That is wicked hot!
All of the fundamental forces which govern our universe—gravity, electromagnetism, and the strong and weak nuclear forces—were equally strong and acted as one during the Planck Epoch. Today, gravity attracts all matter together and is the force that keeps the Earth circling the Sun and our feet firmly planted on the ground. The electromagnetic force governs light and magnetism. It makes radio, television, and cell phones possible and it holds our atoms together. The nuclear forces govern interactions within the nucleus of atoms. In the beginning, they were a single force.
Grand Unification Epoch: At the end of the Planck Epoch, an unimaginably small moment in time, this symmetry broke and gravity became weaker, separating itself from the other forces. (Please refer to the time line.)
As the universe expanded, it cooled down. But at this early stage immediately after the symmetry of universal forces was broken, the universe was still incredibly hot: 1027 degrees Celsius.
The Grand Unification Epoch is so named because the nuclear forces and the electromagnetic force were still unified in a single force called the electronuclear force. This epoch ended 10-36 seconds after the Big Bang when the strong force broke away from the others.
Electroweak Epoch: When the strong force separated from the others, the universe had cooled to about 1015 degrees Celsius and began a period of incredible expansion known as cosmic inflation. Its diameter increased in size by a factor of about 1026 in a small fraction of a second: by the end of this epoch something that had been the size of a millimeter grew to dwarf the Milky Way galaxy. Elementary particles were stretched to cosmic sizes, all within 10-32 seconds. Big Bang indeed.
Quark Epoch: This period began 10-12 seconds after the Big Bang when the electromagnetic and weak forces separated themselves and the four fundamental forces took their present form. The universe had cooled enough that subatomic quarks and gluons—the basic building blocks of matter—could condense out of its roiling energy. The universe was still too hot, however, for quarks to bind to each other to form neutrons and protons.
Hadron Epoch: One microsecond after the Big Bang, the universe had cooled enough to allow quarks to form hadrons such as protons and neutrons, the building blocks of the nuclei of all atoms. A nearly equal number of particles and anti-particles were forged from quarks in the primordial furnace. Particles and anti-particles have an explosive relationship. When they collide, both are annihilated in an explosion that releases tremendous energy. At this point, any hadrons that were destroyed in this way were replaced by others that were created in the heat of the early universe.
The universe continued to cool, reaching the point where hadrons were no longer being created. Most of the particles and anti-particles soon destroyed each other. When the figurative smoke cleared, all of the anti-hadrons were destroyed, but a small number of hadrons were left over. You and I and everything we see are partly made of those leftover hadrons. We exist because of an imbalance in particle/anti-particle destruction.
Lepton Epoch: One second after the Big Bang when most of the hadrons and anti-hadrons had destroyed each other, leptons (such as the familiar electrons) dominated the mass of the universe. The universe was still creating pairs of leptons and anti-leptons until three seconds after the Big Bang. In a now familiar story, most of the leptons and anti-leptons destroyed each other, but a small residue of leptons survived (to later create atoms later in the story).
Photon Epoch: After most of the pairs of leptons and anti-leptons had destroyed each other, photons—particles of light—made up most of the energy in the universe. Photons were still being scattered by electrons. The universe was therefore opaque: light couldn’t shine through the thick soup of scattering particles. Protons and neutrons began to form small atomic nuclei (e.g. helium, lithium, and beryllium).
Matter Domination—1 January, 12:03 AM
70,000 years after the Big Bang (3 minutes at the scale of the Cosmic Calendar), the amount of what we would call matter had grown to become equal to the amount of radiation (e.g. light) in the universe.
Recombination and Dark Ages—1 January 12:16 AM
Up to about 379,000 years after the Big Bang, the universe was filled with a plasma. In other words, the electrons were racing around unattached to atomic nuclei (contrary to our normal experience). It was just too hot for electrons to settle down. Lightning and the sun are two common examples of plasmas. Light is scattered by plasma, so light couldn’t travel very far in a straight line in the early universe. You could say that visibility was practically zero. If you were alive then (and could manage to stay alive), you wouldn’t be able to see the end of your nose.
After 379,000 years, the universe had cooled enough to allow atomic nuclei to capture electrons and form true atoms such as hydrogen and helium. The fancy name for this is recombination. This freed the light that had been held captive by the universal plasma. The universe became transparent; visibility was no longer zero. The consequent burst of light as the universe became transparent is known as the cosmic microwave background.
After the release of photons, the universe was plunged into darkness. No new light was being generated. This was the beginning of the Dark Ages.
- Watch a fireworks show at the stroke of midnight and think about cosmology.
- Make your own big bang (wink wink) at midnight… while thinking about cosmology.
A Brief History of Time by Stephen W. Hawking
The Universe in a Nutshell by Stephen W. Hawking
Born With a Bang by Jennifer Morgan
Character of Physical Law by Richard Feynman
QED by RichardFeynman
- This unit period of time is known as a Planck time after Max Planck, the founder of quantum theory. [↩]
- A unit of length known as the Planck length. [↩]
- A unit of temperature known as the Planck temperature. Note that I use the Celsius scale because it is more familiar than the Kelvin scale to most readers. Even though the Kelvin scale is technically more correct, at these temperatures the difference is negligible anyway. [↩]