Backwards Time Travel Impossible, Scientists Report

There are a handful of scenarios that theorists have suggested for how one might travel to the past, said Brian Greene, author of the bestseller, “The Elegant Universe” and a physicist at Columbia University.
“And almost all of them, if you look at them closely, brush up right at the edge of physics as we understand it.
Most of us think that almost all of them can be ruled out.”

“Space and time are tangled together in a sort of a four-dimensional fabric called space-time,” said Charles Liu, an astrophysicist with the City University of New York, College of Staten Island and co-author of the book “One Universe: At Home In The Cosmos.”
The bending of space-time causes objects to move on a curved path and that curvature of space is what we know as gravity.
Mathematically one can go backwards or forwards in the three spatial dimensions.
But time does'nt’t share this multi-directional freedom.
“In this four-dimensional space-time, you’re only able to move forward in time,” Liu told LiveScience.

A handful of proposals exist for time travel.
The most developed of these approaches involves a wormhole—a hypothetical tunnel connecting two regions of space-time.
The regions bridged could be two completely different universes or two parts of one universe.
Matter can travel through either mouth of the wormhole to reach a destination on the other side.
“Many people who study the subject doubt that that approach has any chance of working,” Greene said in an interview .
“But the basic idea if you’re very, very optimistic is that if you fiddle with the wormhole openings, you can make it not only a shortcut from a point in space to another point in space, but a shortcut from one moment in time to another moment in time.”
SOURCE:
LiveScience.com

I realize I have significantly gone over the amount I am suppose to quote from an article, but I feel that the amount quoted needed to be in this instance.

This was a very intriguing article, and honestly something I had been
hoping would surface sooner than later.

It has always been my opinion that reverse time travel is not possible,
yes you can travel into the future, and even warp time in strange ways,
but one can not go backwards in time.

The article of course does mention to that it may be theoretically
possible at a point far in the future when we have super advanced
science and technology, however, I, as it appears many scientists do
as well, do not believe that to be true.


Comments, Opinions?

EDIT:
Spelling.

[edit on 3/7/2007 by iori_komei]

Mod Edit: To remain in compliance with the T&C, all but the first 3 paragraphs of the external quote were removed. Please visit the link for the rest of the article...It's a good read!

[edit on 3/8/07/08 by junglejake]

That going close to the speed of light to go intot he future, is one reason why we are afraid to go faster then the speed of light. Say you go on a journey for a year. You are 35 years old your friend is the same age, You leave you come back you are 35 your friend is say 40, 50.

I still don't understand how people believe it's possible to travel backwards through time. It's the one and only real paradox spoken of in Science, and the purpose of a paradox is that it causes such a break in mathematical princepals that it simply could not occur... and still exist to be a paradox in the furst place.

Thats the point of a paradox... if it exists, it can no longer exist.

If you travel back in time... you haven't travelled back in time, cause it never happened. lol.
The effect of you going back in time results in a cause that you have never gone back in time, therefore the effect of going back in time cannot come about because you have just removed the cause.

I know it makes for great movie material... and head scratching episodes in Star Trek, but thats all it will ever be... a thing of storytelling.

We can however, warp time in a way that we can affect the speed of which we travel through time... however, you will never find a reverse option on a time machine.


You can however add to that.
If you had 2 exactly the same plains of existance, you could travel to an earlier point in time along the other plain of existance, without it becoming a paradox.
Unfortunately you would not be changing your own timeline. But hey, if you wanted to see what really happened... and don't mind screwing up someone elses universe, then yeah... that is possible.
But we haven't even discovered any alternate universes, let alone the ability to travel to them.

[edit on 8-3-2007 by johnsky]

I think all things are possible...not all things are understood.

It seems we want to 'know' somethings so we label it as a definite..."can do" / "cant do" when in reality...we dont have conclusive evidence.

Just conclusive from our (lack of) experience and knowledge (which is not all comprehensive.)

Peace

d
A
l
e
n

I think it is possible to OBSERVE a point in time that has already occurred. That’s sort of obvious - I don't mean the evidence that an event has occurred (i.e. puddle of water on the floor) because really you are observing the present.

But given enough distance, you could observe that water falling at a point in the past RELITIVE TO YOUR EXPERIANCE OF TIME PASSING. Just have a look at the sun, that’s 5 'light minutes' away, i.e. that was the sun 5 minutes ago.

But you cannot do that the other way - so far as I know. Light cannot be observed before it bounces off the puddle of water or whatever. That is just the plain and well known everyday physics that we all live by, were used to that.

Theoretical physics has leapt far forwards of experimental physics in the last 25 or so years (so my life time), the way I see it there is some serious catching up to do in the experimental side of things, before the way is lost.

The Greeks were masters of thought, and the inventions sprang forward. Do'ya think they (and others) ran out of invention but there minds ran on?

Oh absolutely you CAN observe the past.

I'm quite sure we will eventually devise a way to observe exactly what happened a few years ago.
Like you already realise, it's because you are observing light... not the object itself.

Now if you take light and slow it down, what do you have? Other waveforms right?
Now if you keep going slower, to the point where the waveform is so damn slow that it would litteraly take a year to make it across a room... you should technically be able to absorb that waveform, speed it back up again to be observed in the light spectrum, and see exactly what things looked like back when that waveform was first emitted.

That... or you could just use a distant star to look at the light bounced back from our own planet. Buuut, our technology isnt that precise yet.


At least it would take CSI off of the TV.

[edit on 8-3-2007 by johnsky]

Originally posted by dAlen
I think all things are possible...not all things are understood.

It seems we want to 'know' somethings so we label it as a definite..."can do" / "cant do" when in reality...we dont have conclusive evidence.

Just conclusive from our (lack of) experience and knowledge (which is not all comprehensive.)

I agree, we may not be able to travel back in time with our current understanding of physcics but that does not mean it not possible, it just means that we don't understand the physcis of it. I'm not saying that we will ever be able to do it but I refuse to say its not possible. Maybe not possible yet.

The reason I believe that time travel will never be possible is that to actually travel backwards through time, you would somehow have to gain the ability to revert the universe back to as it was at the point you want to travel.

In other words, you would have to re-create the exact same circumstance down to the quantum level.

There is a reason time appears to move in a forward direction, as reality is composed of a mesh of quantum fluctuations that results in constant change. It is this change that we perceive as time.

Time is merely a measurement of change. Change is a direct result of quantum fluctuations. And quantum fluctuations are a direct result of the universal law.....

Order into Chaos and Chaos into Order.

All the best.

NeoN HaZe.

Originally posted by johnsky
That... or you could just use a distant star to look at the light bounced back from our own planet. Buuut, our technology isnt that precise yet.

That, or you could just send out a huge, polished mirror into space. Or many huge mirrors .

I used to annoy my friends by showing them that backwards time travel could be done using a Distance-Time graph. Increase in speed meant an increase in the slope, right? So then what if you just kept increasing until the line bent over backwards and you went backwards in time?

Jokes aside, the whole stand on time-travel seems to change every few years. I remember reading that going back in time might be possible, but going forward in time is not, because the future hasn't happened yet.

Right, according to Einstein.

It's possible to go back in time. All thats required is to travel faster than the speed of light.

However, also according to Einstein it is impossible to travel faster than the speed of light.

Done.

Here is a great horizon episode about time travel.

www.spikedhumor.com...

And here is a very simple explanation of time, light and time travel.
www.spikedhumor.com...

[edit on 8/3/07 by theBman]

To go back in time is impossible i belive. That stuff already happened. There is no going back. But what i think is possible, is to slow down present time and speed it up, even if you dont go the speed of light.
If you stay in the same spot on earth, and someone flys around it at the speed of light for ten years, the person in the spaceship will have had less time pass than the person on earth. Now what makes me wonder is that since the earth is spinning at thousands of miles an hour, if a person lived on say mercury (whose single day lasts 58 earth days) they would age faster than the people on earth. A good thought.
I wonder how much speed a human body would be able to handle in the vacume of space. I know the space station goes around at abou 20,000 mph. But what is the limit?

if i can go backwards but not forwards... after i go back in time, will i be able to return to my originating time? you say i cant go forwards normally because those events haven't happened yet, but in this case the future had happened already. so can i go forwards to my originating time? i guess itd be like using a tivo...

Originally posted by bokinsmowl
if i can go backwards but not forwards... after i go back in time, will i be able to return to my originating time? you say i cant go forwards normally because those events haven't happened yet, but in this case the future had happened already. so can i go forwards to my originating time?

i guess itd be like using a tivo...

As far as i know its just a matter of perception. So what seems like an hour to you is a year to everyone else. You wont be able to se what your life will be like in the future as you spent that time out the way in your time machine.

Originally posted by theBman
Right, according to Einstein.

It's possible to go back in time. All thats required is to travel faster than the speed of light.

However, also according to Einstein it is impossible to travel faster than the speed of light.

Done.

Here is a great horizon episode about time travel.

www.spikedhumor.com...

And here is a very simple explanation of time, light and time travel.
www.spikedhumor.com...

[edit on 8/3/07 by theBman]

Your forgetting one major thing. Einstein is our "be all and end all" of physics NOW. Who says the next genius to come will not come up with a whole new set of theories and experiments to prove things we find impossible now because of Einsteins laws?

Here is Einstein's quote on quantum physics:

Einstein thinks he has a continuous field theory that avoids 'spooky action at a distance', but the calculation difficulties are very great. He is quite convinced that some day a theory that does not depend on probabilities will be found.
(Albert Einstein to Max Born, 1947, 'The Born-Einstein Letters' Max Born, translated by Irene Born, Macmillan 1971)
www.spaceandmotion.com...

I'm not saying he wasn't a genius because we all know he is BUT in our history people have come along to either disprove OR build upon something that was previously invented or theorized upon.

We have barely touched the surface in quantum physics and in the next 50 years of course will have a better understanding OR fully understand it. Who knows what new worlds quantum physics will get us to. After that we will say "All the laws quantum physics are the limitations physics". Then someone will come along with a whole new set of theories that will get us to the next level. There are no limitations to what we can do because we will never fully understand everything and evolution never stops.

Also if we begin human DNA enhancement to our brains and to our bodies WHO KNOWS what we can do or can't do. IF we could develop humans who could live for 500 years let say could we not send them off to far reaching planets in other solar systems AND maybe find new technologies? The possibilities are endless and we've proven that many times throughout history.



[edit on 9-3-2007 by leafer]

leafer i agree, however if we use that reasoning then nothing is impossible. We may as well abandon everything that we think is fact and discuss methods too outlandish for even the most elaborate si-fi series.

My question is: why on makroscopic level we se a time arrow ( if you spill the milk it is highly unlikely that it will collect itself in a glass again /the second law of thermodynamics: from order to disorder/

and on quantum level you don't see whether time moves forward or in reverse /Lebowitz: "In the language of classical mechanics, matter is made up of particles in perpetual motion; they attract each other when they are at a certain distance apart, and repel each other when very close to each other."/?

The easiest way to think about this and why you can't go back is with entropy being your time line. Entropy in "this" universe is always increasing. There is no way to "go back" to a lower entropy state. While the math works because we have vector equations and they go both ways, the entropy wrench clogs up the system i.e. Earth has moved, your body has changed, etc., etc.

Now the multiverse thing is a possibility, but we have not one shred of evidence that there is any other universe but the one we exist in. At best the wormhole theories would allow for near instantaneous travel within this universe as that would not mess with the entropy.

Time travel forward is easy if you have a super duper infinite energy source - just zip along at .99 C in big loops around the solar system for say 20 years and time will indeed have increased on Earth relative to your time on the ship, but there is no going back - that trip was a one way ticket only....

Yes, thermodynamic arrow (entropy) is clearly pointing forward, so is a cosmological arrow - because if the Universe is not expanding ( we know that it does due to Hubble) but contracting - life would be impossible.
Also biological and social arrow are pointing forward.

But, on the other hand - the fundamental laws of physics themselves are symmetric and don't seem to discriminate between the past and future, so why is time asymmetric!?

As someone puts:" We can't turn eggs into omelets, even though the laws of physics seem to be perfectly reversible, and this brute fact demands an explanation"!

Speaking of multiversis - it sound possible that some other Universe would not be bound with initial low entropy ( point of singularity/ Big Bang/as our Universe.

[edit on 10-3-2007 by blue bird]

Travelling the direction of the Earth's rotation, but faster than the rotation, would, in effect, be slowing down time...

a quick discussion with my workmate here revealed that if he leaves Taiwan (here) at 11am Monday, to go back to Canada (his home), he arrives back at 10am Monday, Canadian time... (not sure which direction it flies)

so what if you kept travelling all the way around to taiwan? if (in theory) it were the same distance, wouldn't you be back 2 hours before you left?

if you could do it faster, and/or more times... you COULD move back in time~

if you arrive back, but the normal [taiwan] time, you have in essence moved forward in time to make up for the difference..

[edit on 12-3-2007 by x08]

You are all correct. But you didn't take into equation "density flux" which is responsible for time dilatation or time acceleration.

As i sain in indigo forum "density flux" can be created from 2 toroidal calems, ajusting frequencies of opposite field.

Closer to speed of light gives more G. But with zero G flux shiels (explained in indigo forum in details) and another density flux shield time can be modified to pass at same rate as on earth. END