Cosmology and our View of the World
The Nature of Time
Lead: Brett Clark
Summary by Katy Randall
The Nature of Time - What is the Center?
The discussion on March 8, 2010, was led by Brett Clark concerning the topic of the nature of time. Brett began the discussion with a slide show, which explained a few concepts of time and the expanding universe. He also mentioned that the article assigned to read on time travel stated that time travel is comparable to walking on a circle in a 4th dimension. With this, he compared Einstein's idea that time was a 4th dimension. The next slide contained a few pointers regarding Einstein's theory of special relativity and how time and space interact. With some confusion amongst the presenter and everyone in the class, Professor Möbius was called to the stand to discuss a little bit about the theory of general relativity and special relativity.
He began talking about special relativity and how the time and space, which we experience is seen as two completely different entities. There is space, which we can measure in three dimensions while there is time, which we experience as flowing forward. Einstein combined the two of these into what he called space-time. The idea of gravity playing a role in time was brought up; that the larger the mass of a star/planet and the stronger the gravity, the slower time is. He talked about how we experience space as straight lines in one direction yet how in the vicinity of a massive object those straight lines aren't there anymore and what you would see is a bent line. This can be tested using a wave of light. Light does not go around a corner unless you put a mirror there to force it around. However, when there is a heavy object in the way, the light that passes along it goes on a bent curve and that can be measured during a solar eclipse.
Greg made a quick comment on how he had once seen something regarding Einstein's idea of an experiment that would send out expeditions where there would be a total solar eclipse to see if light was bent during the eclipse itself. Möbius commented back briefly explaining that if you took a picture of the stars position in the night sky, and then again during an eclipse, when the moon blocks the sunlight you can see the stars and see the light shift in position indicating that the light has moved in a curve.
Going back to the previous subject, the clarification of the idea that time slows down in the presence of strong gravity was mentioned and the question was asked whether, if we lived on a higher gravity surface, would we age slower? Möbius agreed that we would age slower, but for a planet that effect is very subtle. He mentioned how that idea has been tested on earth by placing a very precise atomic clock on two aircraft flying at different altitudes but at the same speeds. The clock on the plane furthest away from the center of the earth was faster than the one at a lower altitude, which shows how gravity effects time.
Tyler brought up the question and idea that if someone were to live on a very dense star and therefore have a slower time than ours on earth and we were able to get some sort of communication or telephone between the two, would we be able to communicate with one another if 1 hour of our time was 10 minutes of their time. Möbius responded that we would be able to do so but since the clocks are so different from one another, the information sent would either be received as far too fast and jumbled or too slow.
Brett then continued to discuss the time travel article and how he was struck by the idea of the arrow of time and how the article compared open versus closed time paths. The article also mentioned the idea of entropy, or disorderliness of the system. The more order, the less entropy it has. Möbius said that order has very little entropy, and gave the example of a messy room to explain how entropy increases. Lauren asked him to clarify the difference between a closed system and an open one. Möbius briefly explained what a closed system was by using the analogy of closing a door, how once you close a door, no energy can go in or out of the room. Entropy cannot be reversed in a closed system because no energy can make it into that system to feed processes that can impart order.
After a brief discussion on the acceleration of the cosmic expansion, Professor Davis mentioned Chapter 5 of the book, “What is the center of the universe?”. It was mentioned how every galaxy is the center of it's own spherical visible universe and the outer region of that is called the cosmic horizon. To understand the cosmic horizon, we can think about the horizon in terms of Earth's. A horizon is essentially the line at which the earth's surface and the sky appear to meet; it is the circular boundary of the part of the earth's surface visible from a particular point. The cosmic horizon however, represents the boundary between the observable universe and the unobservable regions of the universe. It was mentioned that the cosmic horizon is the sphere surrounding what represents the present location of the most distant things we can't see.
The discussion led to a disagreement concerning quantum mechanics and the speed of light, and Lauren requested that we got back onto the topic of time. Brett continued to show a few slides with some questions he posed for the class that reflected on ideas he took out from the reading. Three of the questions asked were the following: 1. Is our consciousness moving across (through) time? 2. How does consciousness travel between parallel universes? 3. What allows or restricts its movement? After these questions were posed, the idea of our consciousness moving through time due to a time machine was discussed. There was a lot of disagreement involving the notion of time machines. Davis believed that the idea of a time machine is absurd and that there is no evidence that it would be even possible to build one, so why speculate what is going to happen when it can never happen? Möbius talked about how time machines allow paradoxical situations, which are illogical, yet according to the theory of general relativity it is possible to have this type of construct of time-like loops. Because time has an arrow always pointing forward, in order to build a time machine, time has to be going in a loop, which will create paradoxes.
The conversation continued when Lauren talked about how in our culture we see time as moving linearly, in one direction forward. Yet she personally feels that time is more circular and that life is this pattern of the same matter breaking down and regenerating into new things over and over again. She doesn't quite know how to make the two coincide, by seeing time as linear and also circular. Möbius agreed that different cultures view time in different ways and how viewing things happening throughout time cyclically is one thing but being able to go back in time because of this circular loop is another. He talked about a time loop structure that allows you to go back in time to fix a bad decision made and how those types of situations are what creates these paradoxes. Brendan added how some global religions believe in cyclical loops and how it is possible that their perception of this cyclical time is of some sort of higher order thinking than that in our own universe. deVries then brought up the problem of having a loop within time itself and how if there were smaller loops within the circularity of time, there would be an object that had a double existence in both normal time and another loop which is impossible. It is impossible to have loops within time, but it is possible that time itself is a loop.
Professor Davis jokingly butted in saying that it isn't because of the paradoxes that time travel can't happen, it just can't happen! Möbius agreed from a physics point of view and how the only way the theory of general relativity would work is by having to travel through a worm hole. This can only be possible if there are infinitely strong gravitational fields to keep that hole open and to have some sort of material strong enough to withstand it. The principle shows where physics can allow that, but there may not be any practical way of implementing it.
Peter mentioned how logic isn't sufficient to prove that something is not possible, and a question was posed to deVries asking whether causality would be included as a part of logic. deVries said that he did not think so, that he thinks the concept of causality is one that we actually don't have any purely a priori access to. We have to discover what causality is by empirically refining whatever conception of causality we inherited from our ancestors; it isn't a concept of logic, but it is not an illogical concept.
The conversation went off topic when deVries was asked to say a few things about modern philosophical thought in understanding the universe. He mentioned that some think time itself is in fact a subjective phenomenon in the sense that the universe itself can be conceived as arranged in fourspace. It is arranged in a way where you think of time as another dimension, so that you become not an object moving through space but rather a space-time worm. The conversation continued talking about the relationship between time and consciousness and how if consciousness is not the creator of time, it is certainly tied to time in a deep way.
Davis then brings up the analogy of the universe being like a book, how it has already been written and now we are just reading it. He mentioned how the future is already there and how you just have to turn ahead to a later page yet at the same time you can still go back to the beginning. deVries argued that what he had just explained would be time travel. If you could jump to a later point in the book and then go back, that would constitute traveling through time. There was some confusion as to the analogy being used, deVries was seeing through the perspective of a character in the book while Davis was talking about being the reader standing outside as an observer.
The idea of prophecy was then brought up and how there has to be some sort of explanation as how time works for that to be possible. Tim posed the question that if someone or something can accurately predict the future, doesn't that mean that there is something operating outside the time limitations that we operate? deVries picked this up saying how scientists are good at predicting the future because of the laws and Tim argued back with examples of prophecies seen within the bible. deVries then said how he believes a lot of those “prophecies” are horoscopish, how if you describe it generally enough, sooner or later something will fill out those prophecies.
Lauren changed the pace of conversation by sharing her thoughts on how if we're all made of the same matter and energy, that her consciousness which merged from her brain could be somehow be connected to someone sitting right next to her because it permeates outward. She is curious if that could explain something like a psychic. Brett said how that assumes that the brain creates a consciousness. He mentioned how consciousness moves through time and cycles, how it might have not always been yours. The conversation then turned to the idea of reincarnation and how when born, your spirit or consciousness is put into that newborn body. Brett asked the question “do you think that consciousness grows as the body grows and learns and is passed on that way, or is it a constant?” Lauren continued by talking about how with reincarnation, one is ultimately trying to lead a higher moral existence with each rebirth. If reincarnated, this could mean that you gain more wisdom with each life. She wonders if the question she asked about consciousness permeating outward and we all being interconnected is even plausible.
Another question was asked about what the definition of consciousness is in terms of its use in the current conversation. Brendan said if consciousness is being defined “as the summation of all the things that you've learned and experienced, then fundamentally everything you've learned and experienced is a part and a piece of the rest of the world”. The example of the current conversation we were having was brought up, how after class ended, each one of us would travel elsewhere but still be connected because of the information we have shared together during the discussion. So in a sense that could mean that our consciousness is tied to information that we've received, learned, and experienced. The concept of neurons in brains was then brought up and how our brains are filled with electrical signals and neurons talking to one another. These electrical fields can be compared to a magnetic field and how it may be possible that we create some sort of small magnetic field in which we can interact with one another subconsciously.
The conversation continued to flow off course and back to a similar idea mentioned before on how if you met yourself in the past, your mind would somehow have to be duplicated and there would be two of you, or would it be the same mind? The lecture finished off with deVries talking about the problems of teleportation devices. He brought up the problem of a teleporter malfunctioning and repeatedly spitting more and more 'yous' out which doesn't make sense because there can only be one. He pointed out that if there are multiple versions of him on the other end of the teleporter, which causes a problem, because each of them may have an equally good claim to be him. Tim asked if we're simply physical matter, why couldn't there be more than one? deVries finished off stating that if we're just physical matter, then when we walk into a teleporter that matter we're made of is taken apart and reassembled on the other side which then means we died in the teleporter. Therefore, the one who comes out at the other side isn't really the real you.
Many questions were asked throughout this discussion and even though topics got off course and no conclusions were officially made, we still covered many good points on the idea of time, time travel, reincarnation and teleportation.