Matter & Energy

The Big Bang, was not an explosion like a firecracker blowing up in an empty field, expanding into space that already existed.  Space itself exploded into existence. Then space expanded, generating matter and energy as it expanded ?, perhaps faster than the speed of light. ? Who knows where it came from!

We have seen water freeze and boil so we know about changes in matter. Matter is frozen energy. When this universe started out, it was so hot that not even atoms could exist, maybe not even elementary particles we recognize today. But thermodynamics kicked in and things began to cool. Some energy froze into particles then atoms. That is what we call matter today.

BIg Bang Timeline:


Click for larger image in a new window.

Matter contains tremendous amounts of energy. The first nuclear bomb was set off near where I am writing this in Socorro, NM. The critical mass of fissioniable material needed for detonation ranges from 10 to 50 kilos depending on materials [uranium, plutonium] and construction [linear, spherical, freestanding, tamped, etc.] . 

Any explosion disperses its ingredients so rapidly that only a small part of the ingredients actually power the explosion. In early nuclear bombs, the actual material converted to energy was a few percent. So maybe only a couple of hundred grams, like the weight of a few coins,  was converted to energy,  giving the equivalent of 20 kilotons of TNT - 40 million pounds = 5.25×10^32 eV: the total energy released from a 20 kiloton Nuclear Fission Device. 

[Aside: An Electron Volt - 1 eV, 
is the amount of energy gained by an electron crossing an electrical field of one volt. 
A simple battery puts out about 1.5 volt.
Molecular bond energies are on the order of 1 eV per molecule.  
1.6 to 3.4 eV: the photon energy of visible light.  
13.6 eV: The energy required to ionize atomic hydrogen. 
200 MeV: The average energy released in nuclear fission of one U-235 atom 

Particles: At first, the universe was too hot and boiling, trillions of degrees. At first too hot for even nuclear particles like protons and neutrons to exist. After a few seconds, some quarks could make neutrons and protons. At this point the neutron / proton ratio was about 1 / 7. There were no nuclei - mostly boiling photons.

Atoms: After the universe cooled some more [for almost a half million years?], atoms formed. At first, only hydrogen, some helium and a little lithium. 

So where did the other stuff  that we are made of come from? ?About a half billion years  later things cooled down enough for stars to form - stars made the atoms we are built of today - carbon, oxygen, nitrogen and some iron. Iron is the heaviest element normally made inside stars' ovens. 

Then where did the even  heavier elements like lead and gold come from? ? Supernovas - exploding stars, usually at the end of their life cycle or some other instability - blow up and go far beyond normal star temperatures and pressures - enough to cook up elements past iron all the way to uranium. You did not want to be close. Everything nearby gets wiped out. To read more follow this link: How atoms are made.

My favorite star - our Sun.

Like your oven at home, Stars are furnaces. When gravity compresses them emough to raise the temperature to millions of degrees, they can cook hydrogen - protons in the center of atoms, into helium and lithium. After the hydrogen is burned, then helium is burned to make carbon, nitrogen, oxygen and eventually iron. Iron is the hottest cookie you can bake in a normal star ! But when some stars explode into supernovas, the temperatures and pressures get high enough to make heavier elements like silver and gold or lead and uranium - the heaviest naturally occurring element.

Molecules: When things cooled down a lot more, to a few hundred degrees Kelvin instead of thousands or millions, atoms could link up into molecules. The most prolific atoms were hydrogen and oxygen, almost never found free at room temperature. But the king tinkertoy that makes the greatest combinations was carbon. It is the ultimate tinkertoy hub - enabling lots of connections:


We will talk more about molecules later.


Next >> The Sky - Planets, Stars & Galaxies

© Gareth Harris 2019                                      Email:                  See also: