Something else interesting...by Śllipse (no login)
Steven Hawking has argued, quite convincingly, that the order in which humans perceive time MUST be the order in which entropy increases. Entropy, in a nutshell, is a measurement of disorder in the universe. If a glass cup falls off a table and breaks into many pieces, you say that its entropy has increased because before there was a particular order in which the atoms were aligned to form the cup, but after the cup breaks the order of pieces is (statistically) random (ie, disordered). Hawking starts off by identifying three things that we always see happen as time goes on, calling them the three "arrows of time". There is the direction in which we perceive time, the direction in which entropy increases, and the direction in which the universe expands. Hawking asks the question of why these three arrows are all aligned the way they are. Why do we perceive time in the same direction that the universe expands and why does entropy (almost) always increase in the future? I'm going to ignore the part about the universe's expansion because the alignment of the arrow of entropy and perception is the really interesting part.
Hawking goes to the root of the very reason for why humans call some things "past" and some things "future". The "past" is the set of events that we remember, while the "future" is the set of events that we don't remember yet. If a cup is sitting on a table, I will not remember when it was broken, but if the cup falls off the table and breaks, I will remember when it was sitting on the table. This is the distinction Hawking gives to our words "past" and "future". So now the question becomes not so much one of philosophy but of natural science. How do humans remember the past? Well the human brain is rather complicated and although we understand a lot of it, there is still a lot more we don't understand about it, so Hawking uses the example of how a computer remembers things, because we understand how computers work very well and Hawking makes the assumption that the basic conclusions for what happens when a computer remembers things can also apply to how the human brain remembers things, only in a much more complicated way. Now, by a computer "remembering" things, we are talking about things the computer saves to its hard disk so that it can be recalled later (temporary memory will also suffice for the argument, but for the sake of simplicity we will stick with just the long term memory of the hard disk). When a computer wants to add something to its hard disk, what its really doing is ordering the bits in a way so that they can be recalled later. By ordering the bits, the computer is DECREASING ENTROPY on the hard disk; the hard disk goes from a state of "disorder" (with random bits from old deleted files) to a state of "order" (with bits that have been set to serve a purpose). However, in order for the computer to decrease the entropy of the hard drive, it must use energy, since everyone knows a computer cannot run without electricity. And in doing so, the computer must necessarily INCREASE THE ENTROPY OF THE UNIVERSE BY MORE THAN THE DECREASE IN ENTROPY ON THE HARD DISK. In using up energy, the computer is using energy that was made by burning fossil fuels or made in nuclear reactors or some similar entropy increasing system, and the heat from the computer also causes air molecules to vibrate more randomly and become more disordered, thereby increasing the entropy in the air around the computer. So, although the entropy of the hard disk decreases, the computer must increase the entropy of the rest of the universe even more.
The same is true for humans. We use up energy from the food we eat in order to form memories in our brains. The food we eat and the air we exhale increases the entropy of the universe by much more than the decrease in entropy in our brains due to the ordering of information (memories). So, Hawking declares that IF we lived in a universe in which time flowed BACKWARDS, we would remember the future and not the past! What this means is that, if time flowed backwards, then entropy would also flow backwards. If entropy decreased with time, rather than increasing with time, then our brains would be more ordered (contain more memories) in the "past" than in the "future" since as time increased, the order in our brains must decrease because the order in the universe has to increase. So, if instead of a cup being on a table and falling on the floor and breaking, the cup would be on the floor broken and then jump up on the table reassembled (this would be a decrease in entropy). However, since we would remember the future and not the past, when the cup was on the floor we WOULD remember it being on the table, and after the cup jumped up onto the table we WOULD NOT remember it having been on the floor. What you will notice is that, in such a universe, we would call the past the "future" and the future the "past", and since we would claim the past was the future, we would also claim that entropy always increases with time! This means that humans MUST perceive time in the same direction that entropy increases. It is impossible for a person to watch a cup jump onto a table because to do so he must order the events in a way that would make him believe the cup didn't jump onto the table but fell onto the floor. No matter which way you turn time, we have to always remember it in the direction that entropy increases.
|Response Title||Author and Date|
|Interesting||on Jul 31|
|because entropy describes behavior within a closed system||mennonite on Aug 1|
|clarifying the bit about atp||mennonite on Aug 1|
|entropy has a definite use...||Śllipse on Aug 1|
|so what would happen if||mennonite on Aug 2|
|Good questions! Too bad I can't answer them. :-P||rpgfan3233 on Aug 2|
|Re: Good questions! Too bad I can't answer them. :-P||Śllipse on Aug 5|
|Re: so what would happen if||Śllipse on Aug 5|
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