Very few people know and understand space time in its entirety, but you could probably ask any common person on the street if they have heard of the equation E=Mc squared and find that they have heard of it. Many people can tell you what the equation stands for, that energy is equal to mass multiplied by the speed of light squared. Some people also know that this equation comes from Einstein's theory of relativity. However, few actually understand what general and special relativity entail. In A Brief History of Time, Stephen Hawking helps us to understand what relativity is all about, and where even this well known theory has its weaknesses.
Einstein's Theory of Relativity is broken up into two parts: Special Relativity, and General Relativity. Special Relativity has to do with the light cones discussed in A Brief History Of Time 1. Those cones in special relativity are always the same anywhere in the universe in this theory. Any event can only effect other events that occur in the future light cone. So if the sun were to burn out, I will still wake up to the sunlight the next morning, and I will still go about my day as normal. That event cannot be effected by the sun, because it is too far away in space to be in the future light cone. However, eight days later, I will not wake up to the sun because that event is in the future light cone of the sun's burning out. Over time, the area in space that the light cone covers increases, and more events can be affected by the event of the sun burning out. However, Einstein did not take into account the force of gravity. When gravity is included, the theory of General Relativity is referred to.
It used to be thought that space time was smooth and continuous (space time being the four dimensional realm in which we live in). However, it has been shown by observing an eclipse that light is bent by gravity. If light is bent by gravity, then the light cones must also be bent, and so the general theory of relativity is created! If the light cones are bent, then space time supposedly must also be curved. It is said that the Earth orbits the sun elliptically because gravity causes the Earth to move along a curved space time track. Earth in space time is actually going straight, but we see it as curved. Because of this curvature, general relativity predicts that time should run slower near larger planets.
The idea that time can be slowed by the curvature of space time is a key point to general relativity, because in this theory, all things are relative to the observer. Distance, size, and even time depend on the observer's view of reality. The most intriguing relativity in my opinion is that of time, that depending on the observing, time may appear to run slower or faster. I think that the key word in this case is appear. A small insect may only live a day, but to that insect, that one day is a lifetime. Many scientists use this a reason to believe that we can go backwards in time, but I find that a relatively poor reason (haha, puns...). In a later chapter, Stephen Hawking puts forth the idea of real and imaginary time. The idea that imaginary time will continue at a steady rate while real time is curved and reversed and other interesting ideas. I think he has it backwards. The fact that all things are relative should imply that we believe in imaginary time! The real time is the one that continues at a steady rate. Let's face it, even though the small insect thinks one day is extremely long, we still see it die at our own rate. Just because the insect thinks it is a lifetime, does not mean it is right. I think that there is one absolute time that is the real time, and the way we experience this time is our imaginary time. Therefore, going back in time is not going to happen! Time marches on, and we can't change that, no matter how long our interpretation of reality thinks time is.
Next week we will discuss time travel in greater detail, and I will do my absolute best to trump any time travel theory that I can find! Send me your theories on time travel and I will do my best to provide evidence as to why they are false, or if they are possibly true, for what reasons it is possible using evidence from either A Brief History of Time or from other sources if necessary (but considering how much information is in this book, I should not need many other sources). Stephen Hawking discusses one time travel theory in great depth: wormholes. So many great time travel theories, so little time!
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Haha, Love the puns. I thought about answerring the last answer for the question, but then I realized that if I did I would have answerred the dumb question. anyways I don't agree with any of the answers completely. Time is relative. realtime can't(sorry bad word)exist because nobody is on the same figurative time line and going by the earth's rotation to measure days, or the seasons and revolution in coordination to the sun isn't accurate because they can be changed, and the first may already be off because of our atmosphere redirecting light. Also with what I read in the book, all speed(as in distance in relativity to time) may be the same, but your personal time changes making it appear faster or slower according to a steady clock.
ReplyDeleteto help with your Indipendant reading for next week, being that time is relative timetravel to this realm in NOT possible. however to that of another may be. To go back intime you would have to enter the realm of a larger being and to go into the future you go into the realm of a smaller being. I beleive in the theory of Fractile Geometry and don't paricularly believe in god(freedom of religion)the above statement makes perfect sense. the problem is how to achieve this goal.
ReplyDeleteAccording to what was stated in paragraph 3 of your entry on General Relativity, we can assume(I know it makes an ASS out of U and ME haha)that linear Geometry does not exist because of gravity. There for to enter another realm you would have to not only escape gravity, but gain enough mass and energy to appear in the larger realm. To escape gravity I think you would have to go in a straight line away from the strongest source of gravity in our case the sun, until you
sorry for the mid sentence break, the hurricane was coming and then the power went out.
ReplyDeleteAnyways... escape the forcefeild of our realm. theoretically possible when you don't let other object's gravity interfere with your course. Theis idea makes more sense when considerring the materializing particles expiriment.
For those not involved with that expirament there was a metal ball in a vaccuum chamber at rest. Newtons law of inertia says it should remain at rest, but it started moving. The scientists conducting the expirement deduced that the cause of motion was from materializing electromagnetic particles. We also decided that energy cannot exist without matter, and therefore there was matter in the socalled vaccuum. The same would happen "large scale" with us enterring a larger realm.
TO recieve the opposite effect you would have to loose mass and energy until you appear as a giant to the lower world. I also think you would have to go to a sourse of gravity. Which sparks another theory that if you travel into a black hole you will already be stripped of mass and energy enough to join society, which exists in a black hole. It is too dense for us to see different particles, but if they were extremely tiny, it would naturally be so. The proportion may even be the same to materials on earth, but smaller.
That also sopports the going back in time theory because we are in someone larger's black hole. All we have to do is leave, and we will end up in the area around the black hole as those particles refferred to earlier which scientists discoverred were in plethera around black holes. (I think I contradicted myself multiple times).
Unfortunately, although these ideas are theoretically possible I don't have confidence in our scientific technology to ever make this a reality. :(
I see your point about going into the realm of other beings to travel in time, but I think that going into another beings realm can only speed up or slow down time. For example, take a small insect such as a fly. Let's say I am transfigured into a fly at this very moment. I am only going to live for 15 to 25 hours until I die. My time will slow down dramatically, because I have so little time to live (in human time that is). Am I in a fly's reality? Technically, yes. Did I go back in time? Not at all.
ReplyDeleteAll right, lets take a different scenario which I think is more of what you are trying to get across. Say I become a specific fly. I join its reality, and according to you, I go back in time, because of the fly's sense of reality. Think about this, though. If I become a specific fly, and go back more than 20 hours, then I do not yet exist! That conclusion makes no sense, so something must be wrong with this theory.
Even if I become a fly, time only "slows down". I am in a fly's reality, but the past even for a fly has already occurred. Think about this. Sure, time went faster or slower for different beings, but at the present time, everything is caught up with each other. What has already happened in our reality is over with. I think, however, that perhaps going into the future may happen, but not the past, because what has happened in our reality has already occurred in all other realities.
All in all, it is very confusing, and I will try to better explain in next week's post. My opinion may change, and I might have new ideas, but next week I will try to explain without completely confusing everyone and avoiding contradictions.
By the way, I will have a post in the future on black holes. Perhaps then your statements on black holes will be cleared up, and not appear so confusing as they do now.
ReplyDeleteMy point doesn't quite work with flies because I believe we are in the same realm. Whatever particles appeared with electromagnetic forse was so tiny that we didn't know they existed until it gained enough energy and therefore matter. and If time has a starting point and time moves slower around bigger objects less time would have passed in the larger realm, meaning that since our time is farther ahead we would be going "back" in the larger demension.
ReplyDeleteIt might make more sence if I describe this in the tems of planes(whichever spelling). humen's and flies' planes intersect at a point other than zero because we can interact with each other and therefore they are currently intersecting(probably the same plane unless they are parabola). however, if we are incapable of interracting with those subatomic appearing particles until they get larger, they would be on a second plane.
In case you still don't get it, imagine a 2d graph. the x axis is called constant time and the y axis is called relative time. there are 2 lines the one with the steeper slope is the smaller demension, so the one with the smaller slope is the larger realm. If switching dimensions you would stay at the same point in constant time(the x value would be the same), but the relative time (y value) would be different. having you go back in relative time.
Sorry if this is a private conversation or something; just tell me and I'll stop.
ReplyDeleteI would like to point out that there is no escaping gravity. There is always matter present. Even if it's only very far away, it's still there and has a mathematical impact.
Correct me if I'm wrong, but didn't the original post say something about gravity impacting time? How can this happen? Time isn't energy or matter, so what is it?
Dorothea, time is considered as an axis of space time, just like length width or height, but a fourth dimension. Gravity can curve light, so it is said that it can curve space time as well. You should read A Brief History of Time by Stephen Hawking. Trust me, it will help you out a whole lot!
ReplyDeleteAt a far enough distance, gravity could be ignored, but it is probably very difficult to position yourself far enough away in our universe, so space time is always crooked and bent everywhere! Fun stuff!