Our Amazing World: What is Time?
by Joe Selzler
Have you considered how strange time is? Normally we take time for granted. We plan our lives by it. Every event of our days needs to be accomplished according to a particular time? How many of us leave our wrist watches at home and find ourselves constantly looking at a bare wrist to check the time. Unfortunately, time doesn't seem to want to co-operate with us. It often seems as if time just won't stand still long enough for us to keep up with life. The alarm clock rings too early. Breakfast is often rushed. The train leaves the station platform earlier than usual. Some days we come to the end and we think, "Where did the time go?"
The amazing thing is that often it works in the other direction and time seems to go a lot slower. When you're late for that meeting, it's strange how it takes the train longer to make the daily trip to the office. When you're really hungry it seems to take an excruciatingly long time for the water to come to a boil to cook your pasta. It seems the clock at school always runs faster in the morning when you have to get to class and slower in the afternoon when you want to go home.
Sometimes we get the feeling that time is really relative. When you're with that pretty girl or that handsome guy the time always seems to pass very rapidly, but when you're watching your younger brother or sister time goes by boringly slow.
Why is this so? Why does time seem to be so relative? We know that in reality, according to our clocks, it cannot be so. We know that clocks do not physically run faster before noon than they do after noon. We can be certain that barring any physical forces on the train it will make the trip to the office in the same amount of time whether we are late for our meeting or not. Therefore, time is relative for us in a psychological sense but not in a physical sense. That is, in our minds the passage of time can vary. But time does not vary in the physical world around us. The problem is that, when we look at a clock, even though we see that five minutes has passed on the physical clock, our own perception of the passage of that five minutes seems to change depending on our circumstances. That is why humans developed mechanical and electronic means of time measurement, so that our knowledge of the passage of time would not be measured by our own subjective view.
Why are we humans so enamoured with time? Many of us even dread the passage of time. That is because there is one fact of life that none of us can escape -- a fact that is dependent on time. Before I discuss that "fact of life" I want to tell you a little about the nature of time that will challenge your faith in its reality. Perhaps you were beginning to think that you could trust your clock on the wall for an accurate time that could be depended on. But are you so sure you can really depend on that clock or even that there is an absolute time that can be measured?
Of course it is obvious to us that because of the physical nature of things mechanical clocks are not accurate. They are subject to the problem of mechanical "run down", which caused problems for early physicists like Sir Isaac Newton. Newton formalised the law of physics that states: A body with no forces acting on it moves in a straight line at a constant speed. 1 The problem for Newton and all physicists in proving whether this law was true is that it is dependent on the notion of time. In other words, to measure whether something is moving at a constant speed we need an accurate measurement of time. To understand why this can be a problem we need to understand the shortcomings of clocks. A clock is a mechanical device that measures motion. Each turning of a gear measures a set amount of time. But what happens if the clock is running slow? How can we be sure of the real amount of time that has passed since we last looked at the face of the clock? We can create super accurate clocks that don't need winding, i.e. atomic clocks. But they still work by the measurement of something; in this case the frequency of oscillation of various atomic particles, such as Cesium 133. (The fact that the United States Naval Observatory Master Clock is a system of dozens of independently operating cesium atomic clocks and a dozen hydrogen maser clocks indicates that even they cannot be absolutely accurate.)
These shortcomings inevitably leave physicists with the need for some sort of universal time. In other words, if Newton's law of motion is to be proved and accepted, then every physicist has to be using the same time, regardless of which clock they use. So Newton posited the existence of an absolute time. He said there was a time that operates in the universe that is absolute and universal _ the same for everyone everywhere.2 In the early days of the study of physics researchers had a standard clock located somewhere that they all could refer to and set their own local clocks to. One such clock was located at the Royal Observatory, Greenwich, England. Thus for practical purposes Newton's law of motion could be proved and applied in various localities. As science progressed and research required more accurate measurements of time atomic clocks were developed.
However, Albert Einstein showed that time is not absolute and universal, but relative. He said that if you and I move differently we may experience the passage of time in a different way, or more precisely at a different rate. Einstein theorised that the faster you travel the slower time moves for you. In his famous "twins effect" he postulated that if you sent one twin off into space at the speed of light when he got back to earth he would have aged less than the twin that stayed behind. This may sound incredible, but the theory was demonstrated to be valid in 1971 when two American scientists flew atomic clocks around the world and found they got out of sync by 59 nanoseconds3 from the ground based clocks.
If this wasn't enough to shake your confidence in your wall clock then this next twist of time probably will. Time is profoundly affected by gravity. Time runs faster in weaker gravity and therefore it will be warped by a stronger gravity. An atomic clock at the top of a tall building and another one at the bottom can show this strange feature of time. The clock at the top will run faster.
Perhaps the object with the most profound effect on time is the black hole. At its surface time will literally stand still relative to us. It has been theorised that if you were to fall into a black hole all of eternity would pass in the split second it would take to cross the point of no return. 4
When you and I think of time we think of past, present and future. But many physicists say that there is no such thing as now, that instead of regarding only the present moment as real, we need to regard the past and the future as existing at the same moment. In other words, they are already there and not waiting to come into existence or have not passed out of existence.
There is a good chance that by this point in the article you are getting a little queasy. You are probably ready to forget the whole question of time and go on trusting that old clock on the wall to keep your life in order. Allow me to bring you back to the fact of life I wanted to talk about earlier, the one that causes all men everywhere to dread the passage of time. That fact of life is death. That's right, you and I have about 70 years or so on this planet and then our bodies will decay, they will return to dust. That is why we are so concerned about the passage of time. Everything in life seems to be affected by that one fact. We live in the knowledge that death is the one thing we cannot avoid.
What if that were not so? What if we did not die? Would we really be bothered with the passage of time? Would it matter if one day, or one year, or one century had passed? If we didn't die we probably wouldn't age. In fact, in order for us not to age the world around us would likewise have to be free from ageing. I am sure we would still be able to notice that the sun rose in the east and set in the west, but would we call this passage of time? We would know night and day, but would we call it passage of time? We would look at our wife or husband and they would look just as they did the last time the sun rose and set - for untold millions of risings and settings.
We could look to the stars, but what if they did not change in their state? What if they never burned out or got dimmer? What if the entire universe around us never changed? Would terms such as past and future have meaning? I suppose you could speculate that they did, but how would you know? You would not have any way to gauge it. I suppose you might say, "Ten days ago I got a new car." However, because you do not age, you will have perfect memory. If you have perfect memory, it will seem as if you got the new car now. You will remember it as perfectly as if it were now.
Likewise, you might say, "Ten days from now I will get a new car." But that will have no meaning for you. Because you will not age any until then, and now you will not be anxious to get your new car. Sure, it will get you from point A to point B faster, but that will have no meaning for you either. When you get the car it will seem as if you always had it. You won't say to yourself, "I am glad I got this car because it gives my muscles a rest." Your muscles won't age so you will not notice any tiredness of muscle, therefore whether you ride in the car or walk will not make any difference to you.
You might be asking yourself, "Does such a state exist?" "Will it ever be possible that you will not age?" "Will death ever be overcome?" "Can I ever escape from time?" In answer to those questions I can tell you that assuredly one man has already done it. That man was Jesus of Nazareth! Not only did he escape death and time but he also lived outside of time. One day the religious teachers of his day were asking him questions and trying to find a way to trap him so they could put him to death. He said to them, "Your father Abraham rejoiced to see my day, he saw it and was glad." They said to him, "You are not yet 50 years old and have you seen Abraham?" He said to them, "Truly I say unto you, before Abraham was, I Am!" What he was saying to them was that He is in the eternal now. He existed before there was time, and he will exist after time ceases. In fact, He is the one by whom time was created: "all things were made through him, and without him was not anything made that was made." (John 1:3)
If you want to understand time then you should try to understand the one who is outside of time.
1. What is Time? By Lee Smolin http://www.fortunecity.com/emachines/e11/86/whattime.html
2. What is Time? Special Report. Focus Magazine: Issue 124, March 2003, Page 34 (Historical note on Isaac Newton) Origin Publishing Ltd.
3. Nanoseconds are a unit of time measurement equal to one-billionth (10 raised to the minus ninth power) of a second.
4. What is a black hole? "Loosely speaking, a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull."
Frequently Asked Questions Page by Tim Bunn. http://cosmology.berkeley.edu/Education/ BHfaq.html#q1
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