65 replies to this topic

[acriasis]

Perhaps this link will help those interested in 'time travel'
http://meiersaken.in...ime_Travel.html

[freetoroam]

SarahAvery, on 20 January 2013 - 03:47 PM, said:

what are you saying..that ghost come from time travel? i don't really understand, maybe like they are from the past and are still here? through time travel?

Not time travel as such...they are impressions in time, and under the right conditions it will be possible for some to see these impressions.
Put it this way, when you look up at the sky at night, it is possible to see a star which has in fact died millions of years ago, but why is it you can still see it now....the speed of light and the time it takes to get to us enables us to still see it, so hence an impression on time and the right conditions, you are in fact looking at something which was once part of the past, but are now seeing it now. So the star which is no longer there, is in your eyes as the impression has travelled through time to yours.

[jaylemurph]

There's been a documentary series about time travel on Saturdays evenings* on BBC1 for the best part of 50 years.

--Jaylemurph

*Well, mostly on Saturdays nights.

[DieChecker]

I think time travel into the future is not an issue. We know how to do that with relativity and high velocitys. What is not known is how to get to the Past. Speculation is that going into the past is impossible.

[freetoroam]

DieChecker, on 20 January 2013 - 07:28 PM, said:

I think time travel into the future is not an issue. We know how to do that with relativity and high velocitys. What is not known is how to get to the Past. Speculation is that going into the past is impossible.

A the moment.
We know we can already see things from the past, its about finding out how we can make that work for us. But honestly, i am not sure if it can or if it would be a good idea to try.

[DieChecker]

Sure, if we could somehow beat the speed of light, we could See into the past... at least see light as it existed at that time, but there is no way to physically teleport/travel there that we know of.

[granpa]

if the universe exists inside a computer then it would be possible for the person running it  to reset to an earlier time

[lightly]

Time travel ?  i dunno,  but we look into the distant past every night . Most of the universe is much older than  NOW .  It's that whole speed of light traveling immense distances thing.
Actually,  i like to think that the entire universe is the same age because everything is in a constant state of RE creation.  ..but that's another story..

[TheSearcher]

jaylemurph, on 20 January 2013 - 07:08 PM, said:

There's been a documentary series about time travel on Saturdays evenings* on BBC1 for the best part of 50 years.

--Jaylemurph

*Well, mostly on Saturdays nights.

You Whovian you. I know what show you are talking about...... :-p

DieChecker, on 20 January 2013 - 07:51 PM, said:

Sure, if we could somehow beat the speed of light, we could See into the past... at least see light as it existed at that time, but there is no way to physically teleport/travel there that we know of.

Beating the speed of light is however not in the realm of the possible though, right now. But in theory this is correct though.

lightly, on 20 January 2013 - 08:17 PM, said:

Time travel ?  i dunno,  but we look into the distant past every night . Most of the universe is much older than  NOW .  It's that whole speed of light traveling immense distances thing.
Actually,  i like to think that the entire universe is the same age because everything is in a constant state of RE creation.  ..but that's another story..

Well the light from the stars we see, is of course very old and could be seen as a kind of time traveling. I'm sure this is not what the initial poster is thinking though.
Having said this, other things have to be considered if you would want to travel in time or think about it hypothetically at least. There is the energy expenditure that would be enormous, also, lets not forget that the earth, the solar system and yes, even the galaxy, move, so you would have to calculate not only time, but also positioning in space. Imagine the processing power you would need for that.  Of course it's all a hypothesis and right now not possible.

[Harte]

DieChecker, on 20 January 2013 - 07:28 PM, said:

I think time travel into the future is not an issue. We know how to do that with relativity and high velocitys. What is not known is how to get to the Past.

Logically, then, since extremely high velocities take us into the future, extremely low ones would take us into the past.

This makes sense, if you think about it.  That is, everyone in the past moved at extremely low velocities!

It doesn't work, though.  I pretty much move damn slow all the time, but I can't seem to travel into the past.

Harte

[DieChecker]

Harte, on 21 January 2013 - 03:40 AM, said:

Logically, then, since extremely high velocities take us into the future, extremely low ones would take us into the past.

This makes sense, if you think about it.  That is, everyone in the past moved at extremely low velocities!

It doesn't work, though.  I pretty much move damn slow all the time, but I can't seem to travel into the past.

Harte

I think the slower you move the closer you get to time standing still. So if you don't move at all then lunchtime seems to take forever to arrive.

[TheLastLazyGun]

Most physicists, such as Stephen Hawking, know that time travel to the future exists.  That's because we are all travelling into the future all the time, and not at the same rate.

That's because the faster something travels, the faster everything else from its perspective travels through time.  So the travelling object has moved forward in time quicker.  This has actually been proven by the use of highly accurate atomic clocks on aircraft and satellites.  But most of the time this is too imperceptible to notice.  Even just walking down the street causes, although extremely imperceptibly, this effect.  But if you were to go at great speeds, say close to the speed of light, this will be very noticeable.  If you wanted to travel, say, 100 years into the future and you had some sort of craft quick enough, you could travel say for a few days or a week travelling at thousands of miles per second.  Time for you on your craft would past by as normal.  It's just that time outside the craft would speed by much quicker.  Then, when you have travelled 100 years into the future, you would come to a standstill.  Just a few days have passed for you on your craft but you now be in the year 2113 or whatever.

And that is why scientists KNOW that time travel into the future is possible.  They just aren't sure if you can travel back in time.

Edited by TheLastLazyGun, 21 January 2013 - 02:39 PM.

[TheLastLazyGun]

DieChecker, on 21 January 2013 - 03:50 AM, said:

I think the slower you move the closer you get to time standing still. So if you don't move at all then lunchtime seems to take forever to arrive.

When you are at a standstill, you travel through time at the speed of light from a stationary observer's point of view.

As you travel quicker and quicker, the slower you travel through time to a stationary observer (or, at least, to someone moving more slowly than you).  So if you are on a spaceship travelling at the speed of light, anyone outside the spaceship who is somehow able to get a quick glimpse into the spaceship through the window would see time on your spaceship at a complete standstill.  However, you yourself wouldn't notice that time has slowed on your spaceship.  You will, however, see time passing extremely quickly outside your spaceship when you look through the window.  So, when you step out of your spaceship, it could well be that half an hour has gone by in your spaceship from your point of view, but 100 years have gone by on Earth.

That's because space and time are linked.  In other words, if you are at a standstill, you move through time at the speed of light from the point of view of a stationary observer.

If you travel at the speed of light, you would have ceased travelling through time at all from the point of view of a stationary observer.

If you travel at half the speed of light, then a stationary observer would perceive you as travelling through time at half the speed of light, and so on and so on.

Imagine space-time as a scale of 1-100, and if you increase one to, say, 40, the other has to go down to 60, etc etc.

The best way to imagine this effect is to imagine that you are on a train and you have a clock.  Attached to the side of the clock is two mirrors facing each other.  Imagine there is a photon of light bouncing from one mirror to the other (for the sake of convenience imagine you can see this photon of light) and the photon hits a mirror once every second, causing the second hand to move forward one second, every second as normal.

You on the train would see this photon bouncing up and down and hitting a mirror once every second.  So, to you, time is passing as normal.

Then imagine that your train goes at high speed through a station.  There is a man on the station platform and, as your train passes from left to right from his point of view, he sees you through the window of the train holding your clock.  He, however, would see the clock and its two mirrors moving from left to right with the train.  He would also see the photon not moving just up and down but also moving left to right at the same time - to him it would be a zig-zagging motion that it's making.  So he would see the photon hitting one mirror but then he would notice that by the time it hits the next mirror that mirror has moved several feet to the right by the time the photon hits it.  So, to him, the photon has to travel a further distance through the air for it to hit that next mirror to make the clock advance a second.  He notices that it takes three seconds for it to travel this extra distance to make the second hand of the clock tick one second.

So this means that whilst a second has just gone by for you on the train, the guy looking at you through the window would actually have perceived that one second for you as three seconds from his perspective.

Edited by TheLastLazyGun, 21 January 2013 - 03:17 PM.

[Winterwind]

TheSearcher, on 20 January 2013 - 08:50 PM, said:

You Whovian you. I know what show you are talking about...

It was rather obvious, wasn't it.

[TheLastLazyGun]

I got this bit slightly wrong:

Quote

So if you are on a spaceship travelling at the speed of light, anyone outside the spaceship who is somehow able to get a quick glimpse into the spaceship through the window would see time on your spaceship at a complete standstill.  However, you yourself wouldn't notice that time has slowed on your spaceship.  You will, however, see time passing extremely quickly outside your spaceship when you look through the window.

It's actually the case that not only would time onboard your spaceship appear to be going slower to any stationary observer (or any observer going slower than you) who looked through the window into your spaceship, but it's also the case that if you looked out of the window of your spaceship time outside the spaceship would also appear to go slower from your perspective.

But the person onboard the spaceship will still time travel into the future, and he will still do so at a faster rate the faster he travels.

This is due to the fact that time is stretched by factor 7 at approximately 99% of the speed of light, which means that in the space traveller’s reference frame, one year is equivalent to seven years on Earth.

What is not commonly known is that if you travelled at the speed of light, you could (in your perspective) get anywhere instantaneously.

For example, the Sun is eight light minutes away from Earth, so it is commonly thought that if you were able to travel on a spaceship at the speed of light your journey from Earth to the Sun would take you eight minutes.

But not for you it would.  To you on the spaceship the journey would actually be instantaneous.  To you it would take NO TIME at all to get from Earth to the Sun at the speed of light.  However, to the people watching your progress on Earth, it would appear to them that the journey has taken eight minutes.  It's all relative.

That's because, if you are stationary, you travel through time at the speed of light.  But if you are going at the speed of light, you don't experience time at all.  There is no time.

Edited by TheLastLazyGun, 21 January 2013 - 04:53 PM.