Atoms, Mass, Energy and Time
Atoms, Mass, Energy and Time
The Birth of Atoms
In all, there are 92 different types of atoms, most of which can be found in the molecules that make up the tissues of your body.
To understand how this is possible, we need to look at what atoms are. The simplest atom is hydrogen, which contains a nucleus composed of one proton, circled by one moving electron. The next simplest atom, helium, has a nucleus with 2 protons, and is circled by 2 electrons.
It is possible for small atoms to combine to form bigger ones...but only under intense heat and pressure...the millions of degrees found in the center of a star. This process is called nuclear fusion.
If the star is large enough, when it runs out of fuel it will collapse in on itself. The relatively cooler outer layers hit the incredibly hot interior, and a massive explosion occurs, called a supernova. Stars that do this don't live very long...while a smaller star like our sun may burn for tens of billions of years, a massive star that is destined to become a supernova may burn out and explode in a matter of a few million years...a ten-thousandth of the lifetime of our sun.
This explosion is so large that it propels the contents of the star out into space...including all the heavy elements it has made. Vast clouds of atoms of all types remain, where once there was a star.
This process has occurred over and over since the universe began some 17 billion years ago. We can observe it still happening today, in our large telescopes.
Despite its familiarity, many people don't really understand what it means.
For example, consider a simple hydrogen atom, basically composed of a single proton. This subatomic particle has a mass of
0.000 000 000 000 000 000 000 000 001 672 kg. This is a tiny mass indeed. But in everyday quantities of matter there are a lot of atoms! For instance, in one kilogram of pure water, the mass of hydrogen atoms amounts to just slightly more than 111 grams, or 0.111 kg.
This is an incredible amount of energy! A Joule is not a large unit of energy ... one Joule is about the energy released when you drop a textbook to the floor. But the amount of energy in 30 grams of hydrogen atoms is equivalent to burning hundreds of thousands of gallons of gasoline!
Can all this energy really be released? Has it ever been?
Another phenomenon peculiar to small elementary particles like protons is that they combine. A single proton forms the nucleus of a hydrogen atom. Two protons are found in the nucleus of a helium atom. This is how the elements are formed ... all the way up to the heaviest naturally occurring substance, uranium, which has 92 protons in its nucleus.
What makes it interesting is that when the two protons are forced to combine, they don't need as much of their energy (or mass). Two protons stuck together have less mass than two single separate protons!
Elements heavier than iron are unstable. Some of them are very unstable! This means that their nuclei, composed of many positively charged protons, which want to repel from each other, are liable to fall apart at any moment! We call atoms like this radioactive.
Both these nuclear reactions release a small portion of the mass involved as energy. Large amounts of energy! You are probably more familiar with their uses. Nuclear fusion is what powers a modern nuclear warhead. Nuclear fission (less powerful) is what happens in an atomic bomb (like the ones used against Japan in WWII), or in a nuclear power plant.
Strange things can happen when you move Fast...things you won't learn about in high school courses, and won't experience while driving down the road in your pick-up. But these things are still very real, and definitely Weird!
The vehicle would appear shorter than normal, and in fact, it would be shorter. If the vehicle were ordinarily 3 metres long, it might now be only 2 metres in length. If you were able to weigh the vehicle, you would discover that it weighed much more than normal. Anybody riding in it would weigh many times their normal weight.. However, the people in the vehicle would not feel any heavier, or any thinner. They would feel and look normal to themselves...but if they looked out the window, they would see the rest of the world moving by, and it would appear to be shrunk.
A much more dramatic effect of moving fast is what happens to time. It seems that the faster you move, the more slowly time runs!
Things get much more interesting if you fly off in a spacecraft that can go really fast...perhaps 200.000 km per second. Now time is really slowing down. Suppose you and a friend are both exactly 16 years old. He stays on earth, but you go off for a trip in our very fast spacecraft. Fifty years go by on earth. (It's a long way to the nearest stars!) You return to find your friend is now 65 years old. You, however, have experienced a phenomenon known as time dilation. Time has been running more slowly for you, in the fast-moving spacecraft. According to you, the trip took only ten years...and you are just 26 years old!
It has been almost 100 years since these theories were first put forward by Einstein and others, and since then they have become accepted as fact by scientists world-wide. More evidence of their validity is also apparent from studies of objects in far distant space.
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