ldt014: Time Travel
#014 - [ Time Travel ] [ blackshark ]
If thinking out loud is a crime and reasoning with ones self illegal then let me be guilty!
BlackShark (as dreamed up by my Friend Sam) Presents the reasons why Physical Time travel is not possible or to rephrase as I am sure I will be proved wrong one millennium, reasons why I feel physical time travel is not possible at this moment in time using our technology dated 1/09/2001.
Well the main reason that immediately occurs to me right now is that surely someone would have come back in time to tell me right now to tell me that time travel is possible and thus stopping me making this text file telling everyone that it cannot be done.....oh hang on there is a knock on the door brb, Ah damn, it was pete from the 25th century telling me that time travel is possible, damn I guess there is the end of my txt file ;)
Ok im joking no one has done this and I very much doubt that anyone will either.
But lets set the jokes aside, a little bit about myself.
I have no in depth knowledge of maths nor physics BUT I can type while drunk so I guess this is an advantage at this point in time as I am drunk and so I am able to write this txt.
I am a computing science degree student in England, I enjoy thinking in depth about subjects that I am interested in so I suppose you could call me an amateur philosopher and from that you can conclude that everything i am about to write here is just utter theorum and nothing concrete or academic. I have a friend called tox to whom I talk about these sorts of subjects and we have in depth conversations about topics like these and I think that we are on par with this subject.
About 2 weeks ago I saw a tv show on channel 4 (of all channels) on time travel and I watched this with some intent as I have been wanting to write this txt file so I guess that is was aptly placed for me to watch and remember (mmmm did someone travel back in time to place that show on channel 4 cos they knew this was going to be written....CONSPIRACY!!), but there were some physics dudes who performed experiments on time and Caesium atomic clocks (the most accurate clocks in the world, they loose 0.0000001 of a second every 27500 years they found that a flight from London Heathrow to New York JFK and back again made the Caesium atomic clocks time change by about 41 millionths of a second when it was compared to the Caesium atomic clock that had been left in london heathrow. Now this tells me one of two things. Either the speed made the time measure accuracy worse and thus its ability to track time had deminished or in fact time had slowed and the clock was showing this, after all time is not tangible so we don't actually know if time has indeed slowed down. With this knowledge you could deduce that a wonna be time traveller, if they could, could travel even faster than the plane and thus reduce the speed of time even further and if possible break light speed and go back or forward in time.
Well me being a cynic has to opt for the former rather than the latter, i agree that they might be able to travel slower in time by 41 millions of a second, BUT they are still in my time, so if its 12:00:00:00 here its only 11:59:59:59 for the bloke that is stood next to me who did the travelling. He has not lost any physical time and would not be out of sync with me and if we take that as fact then most transatlantic pilots are probably about one year younger than what they appear to be due to the amount of 41 milliseconds that they have removed off their lives yet they are still in my present time. :)
So i believe that small insignificant time travel can be possible, but only to a point.
If we look at our current technology right now and think of this scenario "A so called time traveller steals off me and then decided he will go back in time and give it back". The time traveller would have to fly from LHR to NY JFK and back again just to make up the 41 milliseconds so as to give me back what he stole, he would not be able to make this time up and would end up loosing 10 hours to make up the 41 millionths of a second just in order to go back in time, and so it would be a total waste of time. This makes me wonder that if a time traveller could travel the speed of light and beyond would we ever see them again??? They would age 1 year for every 10000 years of our time, so in order to time travel you are going to have to be travelling for a long long amount of earth years.
Even with the technology, say you could travel enough distance in a short enough time to allow you to recoup those 41 milliseconds to allow you to travel back in time, and you went back 41 milliseconds, would i have gone back those 41 milliseconds in time also?
(If you look at time dilation (the faster you go then the slower time goes relative to you) traveling at the speed of light for 2 years is good but on earth roughly 30000 years has past, not too hot if you want to go for a small trip to Ursa Major or Ursa Minor then you might not be comming back to see your kids but infact your great great grand kids instead! :))
Or would i still be in the present and he be in an apparent past time interacting with a past self of me and having actual objects appear before my very eyes because the time traveller is 2 minutes back in time putting them there??
The time traveller might be in a time zone 41 milliseconds behind me but they would still be in my time zone and my physical plane enacting with me, thus this makes the time travelling totally irrelevant. As in effect he is still in my time zone but still 41 milliseconds behind.
Now here comes some paradox's, He is 41 milliseconds behind me but yet he is still in my time zone.....weird, its like having 5 people in the 100 meters running race and the winner comes both second and first :)
So from what i have written so far you can summarise that i agree on a relative slow down of time (you travel fast enough nd 59 milliseconds passes for you but 1 second passes for me) but not an actual time travel as such (you can go back in time 41 milliseconds and get out of a plane and interact with past images of yourself). The person "time travelling" has only travelled at speed but not through a time tare.
Now a simple theory on relativity for those who don't know Einsteins Law on it.
So where do we start? Well let us start with one of the greatest triumphs of the human mind, the great theorem of Pythagoras, a true pillar of all mathematics and physics. The theorem, which is applicable to right angled triangles in flat Cartesian (Newtonian) space takes the form of:
c2 = a2 + b2
where a, b and c are the lengths of the sides of the triangle.
Next we will jump straight to Einstein's theory of Relativity which states that neither time, length, or indeed mass remain constant additive quantities when approaching the speed of light c. Our simple ideas of time and space come from the fact the we are so used to living in a three dimensional universe. Einstein showed that this was simply not true and in fact all the "foundational" three laws of Newton have to be fudged by the Lorentz factor
Lf = (1 - v2/c2)-1/2
There are, however, certain quantities that do remain constant. These constants are related to four-dimensional quantities known as metric tensors. From this Einstein proved that space and time are two aspects of the same thing and that matter and energy are also two aspects of the same thing. From the second of these concepts we get the most famous equation in physics
E = mc2
Now since time and space are aspects of space-time and we wish to travel through time and not build atom bombs we will leave E=mc^2 for the moment. To illustrate this, look at the extension of Pythagorean theorem for the distance, d, between two points in space:
d2 = x2 + y2 + z2
where x, y and z are the lengths, or more correctly the difference in the co-ordinates, in each of the three spatial directions. This distance remains constant for fixed displacements of the origin.
In Einstein's relativity the same equation is modified to remain constant with respect to displacement (and rotation), but not with respect to motion. For a moving object, at least one of the lengths from which the distance, d, is calculated is contracted relative to a stationary observer.
The equation now becomes:
d2 = x2 + y2 + z2 (1-v2/c2)1/2
and this implies that the distances all shrink as one moves faster, so does this mean there are no constant distances left in the universe? The answer is that there are because of Einstein's revolutionary concept of space-time where time is distance and distance is time! So now
s2 = x2 + y2 + z2 - ct2
and this new distance s (remember s stands for Space-time) does indeed remain constant for all who are in relative motion. This distance is said to be a Lorentz transformation invariant and has the same value for all inertial observers. Since the equation mixes time and space up we have to always think in terms of this new concept: space-time!
The theories that Einstein told and explained have been show to work and exist by physics experiments and so are shown to be fact.
If person A stands on a plane And flies over person B and fires a gun then the projectile fired by person A travels at 2 different speeds. Now this seems rather Stupid and incomprehensible to you now but read a little more.
The plane travels at 500 MPH and person A fires the gun and the projectile fires out at 500 MPH, to the person in the plane the projectile is travelling at 500 MPH BUT to the person on the floor the projectile is travelling at a much greater speed which is worked out as follows.
Speed of moving object + speed of projectile = The Sum of the total speed.
But the calculation for person A is just speed of projectile as they are the moving object.
Thus to person B the projectile is travelling at 1000 MPH where as to person A it is at 500 MPH.
The actual speed is 1000 MPH but the person in the plane sees it as 500 MPH but the speed is only relative to each individuals situation.
Thus two speeds can be applied to one object at the same time.
So this ties in with my theory on time travel how? i hear you ask.
Well person A Travels transatlantic from LHR to JFK and back, for Person A it is 41 milliseconds earlier than than person B. In effect it is both 41 milliseconds earlier and also the present time for both people creating a weird time paradox.
IF one person travels back in time they see the time as 11:59:59:59 but the person who never moved sees it as 12:00:00:00 so the time shift is only relative to the person who made the time travelling.
So no actual time travel has actually been made only a relative time shift has been created. I would like to see this happen when we can travel at the speed of light or faster (according to Einstein no object can go greater than the speed of light in a vacuum) Then maybe this time shift may be noticeable but at the moment it is not.
So relative to the person "travelling", "time travel" is possible to a degree. They travel for 3 of their years but 30000 + earth years have passed even though the same earth time has past for the traveller, the person travelling has had a different time relativity to those on earth.
But now lets look at actual time travel......
Our basic ideas on time travel are this.
To go back in time we need to go faster than the speed of light. To allow us to travel We will need a place where we can move without any restriction on speed or a place where we can have virtually no friction or if possible no friction at all as then all energy can be transformed into acceleration rather than using energy to country friction and prevent deceleration. As Einstein said no body or matter can go faster than the speed of light (at least in a vacuum) so we could not time travel in space (as space is basically a vacuum) so we would need to do it on earth and have the electronics and technology to allow us to do this. If we were able to attain a speed faster than light we would be travelling so fast we would be passing things before we actually saw them so navigating at this speed would be impossible without devices that could see faster than the speed of light (watch red dwarf for a comic summarisation of this (hollys massive IQ), note that electricity travels at the speed of light) IF I could travel faster than the speed of light for 3 earth years I would go back in time for 3 earth years so i would be in effect 19, but in actual physical terms i would still be 22 in our current time but id be standing in the past time, if it were possible, so even though i have gone back in time i am still physically my own time.
Now if i was to go back in time and i could see myself i would not be able to interact with this past time, and this is the reason why i think this:
When you go back in time you are not travelling to a past physical existence but in fact you are travelling through a light barrier. In order to go back in time 3 years you will have to travel so as to reach a speed faster than light, as the light has already past and gone you wont be able to interact with it as it is a past light and past happenings so i feel the best we could ever do is observe due to the fact there are no physical existence. If you are able to time travel in a physical sense the traveller might go back in time but the only time he will travel back into is the present as that is the only physical time that exists. (i am ignoring dimensional tares and time rifts (if this occurs during time travel who knows) and also dimensions beyond which we cannot see......4th, 5th, 6th..... Nth Dimension (dont think zool!!))
So while thinking about it i don't see how travelling faster than light can infact make you go back in time to a past physical time, i can see how travelling at light speed or faster than light can slow your time down and allow you to travel 30000 earth years in only 3 of you own years, so in effect you may have travelled into the future but you still had to travel for those 30000 earth years to do it, you don't notice the 30000 years and you didn't go there immediately, i also don't think that you can go back in time back into the past time that you used to be in before jumping into the future as you will be travelling in a slowed earth time but the time on earth wont change along with you and will still continue in a linea way at the old speed.
What does this have to do with time travel? Imagine an imaginary journey to Andromeda, some 2.2 million light years away. For the time being ignore the problems of propulsion (like they do in all Sci-Fi films!). Firstly, lets assume a Newtonian Universe and we'll ignore the effects of gravity and friction (not much of this in space anyway). The first problem: how fast do we accelerate? Well, if we could accelerate at an infinite rate we could reach an infinite speed instantly and reach our destination in no time at all! Unfortunately, if we were to do so we would experience infinite acceleration forces and be crushed to an infinitesimally thin film instantly. Not much use. The gravitational field of the Earth of 1g (9.81 m/s per second) is however a comfortable acceleration to subject us to, so lets assume the acceleration of our spaceship will be 1g.
So how long to Andromeda at 1g using Newton's theory? We will add the condition that we wish to stop when we get there, if only to turn around and come back. The best time we can make is achieved by accelerating for the first half of the journey and decelerating for the second. The total time for the trip can be calculated to be some 2,065 years. Rather a long time really. Consider the same journey in an Einsteinian Universe. We now have a limited maximum speed (the speed of light), which at 1g is reached in 30,000,000 seconds, or a little under 354 days. After we reach this speed, how much longer will it take to reach Andromeda? The answer is no time at all! For the distance to Andromeda will have shrunk to zero for the spacecraft. However to the people back on Earth a considerable length of time would pass: some 2.2 million years. This is all due to time dilation....thank you time dilation!! :)
What about powering the engines? For the Newtonian case the power requirement is enormous, even assuming perfect efficiency. The energy required would be 5.1*10^26 Joules for a 10 tonne spaceship. This is rather a lot. NASA's space shuttles are not really up to it I'm afraid. In the Einsteinian Universe the power is still huge since the mass of the ship rises and becomes so large! And unless you get very close to c the distance to Andromeda will not shrink very much and it will take ages to get there.
Friction: though space is essentially empty, with increasing speed the little matter that there is would become increasingly concentrated. In addition, its relative mass increases, consequently, we would encounter it with ever greater density. Indeed as we approach the speed of light the whole Universe becomes concentrated into an infinitely thin, and consequently infinitely dense, barrier in the direction in which we are travelling. The force of friction would increase accordingly.
Special relativity tells us that it is impossible for us externally to accelerate a solid object up to the speed of light, because this requires an infinite amount of energy. This is true for a spacecraft, you, or even something as small as an electron. In fact true for anything that has a finite rest mass. For, as we impart energy to an object, its mass increases at an ever-increasing rate and we can never get to the speed of light since mass becomes infinite. To make progress we must move to the physics of general relativity and beyond. It is known that once the density of matter-energy becomes large enough in a region of space-time the laws of quantum mechanics take over and uncertainty becomes the order of the day. This means that we could achieve a quantum tunnelling through the light barrier to reach trans-light velocities. The only way to amass such energy is to play with black holes.
So after thinking about this my conclusions are as follows.
A minor relative time change for the traveller is possible at this time with our technology but this time change means nothing as they move back in time into the present time so does this mean that they are already in the future to allow them to move back in time to the present?
If we are able to move back in time we wont be able to interact with the past time as we are already in the only present physical time and going back in time will only allow you the chance to see past light and no actual physical matter unless of course you can make a dimensional shift (supposing they occur) which i cant see at all.
Time dilation occurs as this has been shown and when this is combined with Einstein and his idea that says no body can travel faster than light in a vacuum i can see that you can travel into the future for you but it is not a true time travel, its like recording coronation street or neighbours, they last 30 minutes but if you pause them in the middle the can last longer even though they are still the same length, this is the same sorta thing that happens here, you pause your time and then pop out when have had enough and real time has continued even though you have only been gone 3 years.
IF you break the light speed barrier to go back in time how do you go forward?? Go the speed of light slower than the speed of light.....but even that is still forward thrust....just inversed forward thrust, so another paradox occurs, we need 2 ways of travelling for only one direction.
One last thing before i go, now correct me if im wrong.........but i would guess that light travels at the speed of light (hence the name) and so if it travels at the speed of light does that mean it takes no time to get anywhere (time dilation) and thus the speed of light is infinite relative to the light itself meaning that light instantaneously gets from point a to b???? Just something i was thinking of could we achieve the speed of light while spinning in a circular motion rather than moving horizontally or vertically and would it be possible to harness the speed of light in order to propel us to that much needed speed in order to achieve time travel and is light the actual factor we need to beat in order to go back or forward in time or is it something that we just don't yet know????????????
I'm sure i'll write more on this subject and similar subjects closer to a time gone past in the future or a future time in the past that has yet to be.......... BlackShark@hushmail.com
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Long Dark Tunnel 2001. - http://ldt.aguk.co.uk - ldt@hushmail.com
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