Cosmology | Dark Matter | Big Bang | Other Tutorials The Big Bang: Roughly 12 billion years ago, our universe did not exist, not even light, and the only thing was a large clump of matter. It was only till something caused that clump to explode. All the matter was flung out, not entirely flung, but the space in between them expanded in scale. The matter first spread in uniform, then evolved to a world containing dark matter, star clusters, galaxies, and solar systems. Every second, our universe expands, still possessing the energy of the Big Bang. With the Big Bang came the birth of time. Evidence for this theory: Scientists have noticed that galaxies are actually moving away from each other. It is actually an illusion as it is rather the space between them that is expanding. For things to move away, kinetic energy must have been in contact with both sides, and this means they must be side by side in the beginning. After some calculations involving the speed of the expansion, scientists believe that the universe was actually a large clump of matter 12 billion years ago. Scientists then deduced more facts from the leading theory the Big Bang. One of which was that with the Big Bang, there would be intense radiation, although they may have weakened. Today, we can still see that there is radiation all over us just by turning on our radio. The cackling sound on vacant channels is actually caused by radiation left over in space. The amazing Vacuum: Scientists discovered two strange facts about vacuum. Firstly it is actually composed of positively and negatively charged particles which continually cancel out each other. Secondly, it has a repulsive gravitational force, which is that it pulls all matter away from each other. Doppler Effect: This is the law of physics that the nearer the light or sound wave is to you, the higher its frequency and vice versa. The size and shape of the Universe This is an interesting part which will send you flying out of your mind. Up till now, the fate (referring to the size and shape) of the Universe is still uncertain. Why? Read on and find out! The inflation theory: The Universe is believed to inflate rather than expand. Thus, the objects in the Universe e.g. galaxies actually has the same position when looked upon at a larger scale at present despite the inflation of the Universe. Shape of the Universe: If the Universe expands by inflation, the Universe would actually be flat. To be flat, the Universe must have a critical density, which is a certain density which balances gravity. If the total density of the Universe is more, gravity will eventually overcome it and everything will be pulled back into a sphere. Scientists call it the Big Crunch. If it is less, the Universe will continue expanding forever as vacuum pushes everything away. If equal, the Universe’s size will be a constant as all movements come to a stop. As the Universe does has a critical density (see “dark matter”), why is it still expanding? Funny energy: Scientists believe that a type of energy called “funny energy” is pushing everything away. As you can now see, nothing is certain. As there is a limit for science. Hubble’s Constant or Ho: The golden value which is needed to find out the rate the Universe is expanding, which could lead us ultimately to finding out exactly how old is it (present estimation is 12 billion years old). Ho can be found with this formula: Ho = V/D. D=distance of a selected galaxy from Earth. V=Velocity of galaxy moving away from Earth. Scientists find the velocity by observing rate of changes in colour given out by moving galaxies. As a galaxy moves away, the light frequency gets lower (The Doppler Effect) and thus, the colour changes. The distance is found by having “Markers”. Bright stars of known distances are used as the “markers”. Scientists then compare the brightness and colour of the “marker” and the light given out by the outer galaxies to find out the distance between them. The distance between them is then added to the distance of the “marker” from Earth. Cosmology | Dark Matter | Big Bang | Other Tutorials
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