What is Space Time and How it Works | Documentary

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The time scale of the universe is very long compared to that for human life. It was therefore not surprising that until recently, the universe was thought to be essentially static, and unchanging in time. On the other hand, it must have been obvious, that society is evolving in culture and technology. This indicates that the present phase of human history can not have been going for more than a few thousand years. Otherwise, we would be more advanced than we are. It was therefore natural to believe that the human race, and maybe the whole universe, had a beginning in the fairly recent past. However, many people were unhappy with the idea that the universe had a beginning, because it seemed to imply the existence of a supernatural being who created the universe. They preferred to believe that the universe, and the human race, had existed forever. Their explanation for human progress was that there had been periodic floods, or other natural disasters, which repeatedly set back the human race to a primitive state.

This argument about whether or not the universe had a beginning, persisted into the 19th and 20th centuries. It was conducted mainly on the basis of theology and philosophy, with little consideration of observational evidence. This may have been reasonable, given the notoriously unreliable character of cosmological observations, until fairly recently. The cosmologist, Sir Arthur Eddington, once said, ‘Don’t worry if your theory doesn’t agree with the observations, because they are probably wrong.’ But if your theory disagrees with the Second Law of Thermodynamics, it is in bad trouble. In fact, the theory that the universe has existed forever is in serious difficulty with the Second Law of Thermodynamics. The Second Law, states that disorder always increases with time. Like the argument about human progress, it indicates that there must have been a beginning. Otherwise, the universe would be in a state of complete disorder by now, and everything would be at the same temperature. In an infinite and everlasting universe, every line of sight would end on the surface of a star. This would mean that the night sky would have been as bright as the surface of the Sun. The only way of avoiding this problem would be if, for some reason, the stars did not shine before a certain time.

In a universe that was essentially static, there would not have been any dynamical reason, why the stars should have suddenly turned on, at some time. Any such “lighting up time” would have to be imposed by an intervention from outside the universe. The situation was different, however, when it was realised that the universe is not static, but expanding. Galaxies are moving steadily apart from each other. This means that they were closer together in the past. One can plot the separation of two galaxies, as a function of time. If there were no acceleration due to gravity, the graph would be a straight line. It would go down to zero separation, about twenty billion years ago. One would expect gravity, to cause the galaxies to accelerate towards each other. This will mean that the graph of the separation of two galaxies will bend downwards, below the straight line. So the time of zero separation, would have been less than twenty billion years ago.

At this time, the Big Bang, all the matter in the universe, would have been on top of itself. The density would have been infinite. It would have been what is called, a singularity. At a singularity, all the laws of physics would have broken down. This means that the state of the universe, after the Big Bang, will not depend on anything that may have happened before, because the deterministic laws that govern the universe will break down in the Big Bang. The universe will evolve from the Big Bang, completely independently of what it was like before. Even the amount of matter in the universe, can be different to what it was before the Big Bang, as the Law of Conservation of Matter, will break down at the Big Bang.

Since events before the Big Bang have no observational consequences, one may as well cut them out of the theory, and say that time began at the Big Bang. Events before the Big Bang, are simply not defined, because there’s no way one could measure what happened at them. This kind of beginning to the universe, and of time itself, is very different to the beginnings that had been considered earlier. These had to be imposed on the universe by some external agency. There is no dynamical reason why the motion of bodies in the solar system can not be extrapolated back in time, far beyond four thousand and four BC, the date for the creation of the universe, according to the book of Genesis. Thus it would require the direct intervention of God, if the universe began at that date. By contrast, the Big Bang is a beginning that is required by the dynamical laws that govern the universe. It is therefore intrinsic to the universe, and is not imposed on it from outside.

Comments

gary stevenson says:

2 cosmic singularities, past and futur, Big Bang and Black Holes for space doesn't exceed space and the termodynamic Arrow is illusions galore.

Respect Be respected says:

Please don't ridicule me. The tiny energy before the Big Bang had space? Not able to grasp how something comes into existence from nothing.

LaDarian Jr. says:

Space time ps4 please and multiplayer

Dementor says:

If space time curves like the net of a trapeze artist why are the solar system planet orbits elyptical and not circular? Does not space time curves proportionaly? or is sun an ovoid-shaped object instead of a perfect sphere?

David Kennedy says:

This video is like cavemen explaining how fire works . Like I see all of you recognize something but where’s the logic ? What gives rise to space time? Is it even there or is it a result of deep “space” layer or dimensional reactions ? The very idea of inflation is giving credit to space between space that could be “filled” or at least altered .

Rafael Dasigni says:

Before Creation Must come Destruction.

j gee says:

All these people are idiot's.. how could they know what they think they know when someone who didn't know taught them what they know!

kowshik karmagam says:

Lots of useless matter is discussed…

Elizabeth Bradley says:

Why else would humans hoard money

Elizabeth Bradley says:

No wonder rich people hoarding their money. They must know that their money and sacred intelligence is worth something when we all die from our own dead planet

Elizabeth Bradley says:

Atoms will make rise..

Elizabeth Bradley says:

Wow the dark energy part

Elizabeth Bradley says:

Not a hard concept to grasp

Marial Mabor Majok says:

Gradual process is God! Human isn't in God image. GOD however would have visited us one day in person. we spent 13.8billion yrs without any visits oops!

Benjamin Pope says:

That black bitch is bad as shit

xobiusify says:

you know why we will never understand dark energy? because everything is simulation… we all are…

glitch gamer says:

Go back to the future? Something isn't right here,it should be go back to the past 22:35

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