Joined: July 2005
379,000 years after the Big Bang
The temperature of the Universe is approximately 3000 kelvins. At this temperature hydrogen nuclei capture electrons to form stable atoms. This event known as recombination is particularly significant because free electrons are effective at scattering light, which is why fire is not transparent, while hydrogen atoms will allow light to pass through.
guess that time number Chaisson gave was +- about 79,000 +- 21% and not +-300 % as you implied.
HHow did the universe really begin? Most astronomers would say that the debate is now over: The universe started with a giant explosion, called the Big Bang. The big-bang theory got its start with the observations by Edwin Hubble that showed the universe to be expanding. If you imagine the history of the universe as a long-running movie, what happens when you show the movie in reverse? All the galaxies would move closer and closer together, until eventually they all get crushed together into one massive yet tiny sphere. It was just this sort of thinking that led to the concept of the Big Bang.
The Big Bang marks the instant at which the universe began, when space and time came into existence and all the matter in the cosmos started to expand. Amazingly, theorists have deduced the history of the universe dating back to just 10-43 second (10 million trillion trillion trillionths of a second) after the Big Bang. Before this time all four fundamental forces—gravity, electromagnetism, and the strong and weak nuclear forces—were unified, but physicists have yet to develop a workable theory that can describe these conditions.
During the first second or so of the universe, protons, neutrons, and electrons—the building blocks of atoms—formed when photons collided and converted their energy into mass, and the four forces split into their separate identities. The temperature of the universe also cooled during this time, from about 1032 (100 million trillion trillion) degrees to 10 billion degrees. Approximately three minutes after the Big Bang, when the temperature fell to a cool one billion degrees, protons and neutrons combined to form the nuclei of a few heavier elements, most notably helium.
Have you heard of Dr. Hawking? He is usually respected and a person careful with his words.
He does not refer to free protons as an element nor as hydrogen. He does refer to the combination of a proton and a neutron as the element helium. There is no other designation for that combination as it is not a single elemental particle but rather the comination of two elemental particles.
Your decision to refer to protons as hydrogen is not in agreement with Hawking.
Guess who I agree with on the basis of their credentials.