# If you travel faster than light, what happens?

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#### Sohail

##### Active Member
You would probably die from running so fast but i think you could travel through time like this as i heard it's possible to travel into the future but not into the past...

#### Sohail

##### Active Member

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If it was possible to travel faster then the speed of light, would time reverse itself (like backwards time travel) or just not exist?

Your question is a very interesting one, and it is great to see that you are thinking about Professor Einstein's theory in this way, but unfortunately, you're probably not going to like the response. When you assume that it's possible to travel faster than the speed of light, you're taking the laws of physics and punching them in the stomach and throwing them down the stairs.

The problem is that you can't say, 'Hey, what would happen if you could go faster than the speed of light?' because that's totally physically impossible. It's not possible to go faster than the speed of light, so the laws of physics can't possibly say what would happen if you imagine things that way in some hypothetical universe. Physics is a complete package: once you decide to ignore one physical law, you're ignoring them all.

You run into a similar problem when you ask 'What if I could divide by zero?' or 'What if I could build a perpetual motion machine?' or 'What if I went back in time and killed my grandfather before I was born?' There's no answer, because the question doesn't make any sense.

Of course, this doesn't bother the writers of Star Trek. They go faster than the speed of light every show and travel into the past like it's a trip to Disneyland. This brings up an interesting point, however: The idea of a space-warping engine is NOT entirely a bad one! Warping space would allow you to travel as if you were moving faster than light by changing the structure of the universe, at least temporarily. You would end up in a certain location much faster than if you travelled there the 'normal way,' kind of like a secret passage. Happily for relativity, you would STILL not actually be travelling faster than the speed of light in local space, so Einstein's 'speed limit' still holds.

The point is that though it's fun to think about and enjoy in science fiction, truly going faster than the speed of light is a violation of the laws of physics and therefore can not really be discussed by physics. I can't say time would reverse itself or not exist or anything because those aren't even options. It's like if I invited you out to dinner and you told me you absolutely couldn't come, but then I asked you whether you were going to have the soup or the salad!

Answered by: Steve Healey, Physics student, Rutgers University, New Jersey

One of the reasons that prevent any object with a mass going at or faster than the speed of light is that the mass is not constant - it increases with velocity and it goes to infinity at the speed of light. So that eventually you need infinite amounts of energy to accelerate infinite mass past the speed of light mark! (and as far as I know we have yet to find an infinite source of energy

However if you would still like to choose if you are having the soup or the salad at the dinner you will not attend here is a thought.

We really do not know what would happen to time when an object passes the speed of light. The only thing we have to rely on is the Special Theory of Relativity (Einstein 1905) and according to it time in a moving reference frame (say your space ship) goes slower as compared to a stationary frame (say Earth) the faster you go. In fact the equation that governs this so called time dilation is given below:

So you see when you start off - at zero speed (0% of speed of light) your time is just regular i.e. the time slowing factor (xt) is equal to 1. As you speed up your time runs slower by the factor shown on the y-axis. As you are approaching 100% of the speed of light your time slows more and more until it is infinitely slowed down. (You should realize that everything slows down including your heart beats, your thoughts, etc.) So for an example if your ship goes at 98% of the speed of light and you take a one year journey, when you return to Earth five years have gone by.

This region of speeds below 100% of the speed of light is the region of our regular time or Real Time.

Now say somehow you were able to go faster than the speed of light (i.e. the v in the above equation is now greater than c the speed of light). The equation will then give us a square root of a negative number on the right hand side (which is an imaginary number.) Well I can factor out the imaginary unit number (i or the square root of minus one) and plot the result on the same graph. This region I call Imaginary Time since it is some weird time with an imaginary unit attached to it (so I don't really know what this time means.)

However you see that time in this imaginary region will speed up from infinity to the regular time speed of 1 and continue speeding up. At 140% or higher speed of light, time slowdown factor is less than one, i.e. time will go faster than in the stationary frame! So for an example if your ship goes at 200% of the speed of light and you take a one year journey, when you return to Earth only about 7 months have gone by. However I need to stress again that this is just a crazy thought experiment which produces some weird imaginary time and has no physical meaning.

And look at this too :-
What is time? Is time travel possible? For centuries, these questions have intrigued mystics, philosophers, and scientists. Much of ancient Greek philosophy was concerned with understanding the concept of eternity, and the subject of time is central to all the world's religions and cultures. Can the flow of time be stopped? Certainly some mystics thought so. Angelus Silesius, a sixth-century philosopher and poet, thought the flow of time could be suspended by mental powers:

Time is of your own making;
The moment you stop thought

The line between science and mysticism sometimes grows thin. Today physicists would agree that time is one of the strangest properties of our universe. In fact, there is a story circulating among scientists of an immigrant to America who has lost his watch. He walks up to a man on a New York street and asks, "Please, Sir, what is time?" The scientist replies, "I'm sorry, you'll have to ask a philosopher. I'm just a physicist."

Most cultures have a grammar with past and future tenses, and also demarcations like seconds and minutes, and yesterday and tomorrow. Yet we cannot say exactly what time is. Although the study of time became scientific during the time of Galileo and Newton, a comprehensive explanation was given only in this century by Einstein, who declared, in effect, time is simply what a clock reads. The clock can be the rotation of a planet, sand falling in an hourglass, a heartbeat, or vibrations of a cesium atom. A typical grandfather clock follows the simple Newtonian law that states that the velocity of a body not subject to external forces remains constant. This means that clock hands travel equal distances in equal times. While this kind of clock is useful for everyday life, modern science finds that time can be warped in various ways, like clay in the hands of a cosmic sculptor.

Watch The first science-fiction story about time travel appeared in the 1880s.
Science-fiction authors have had various uses for time machines, including dinosaur hunting, tourism, visits to one's ancestors, and animal collecting. Ever since the time of H.G. Wells' famous novel The Time Machine (1895), people have grown increasingly intrigued by the idea of traveling through time. (I was lucky enough to have chats with H.G. Wells' grandson, who told me that his grandfather's book has never been out of print, which is rare for a book a century old.) In the book, the protagonist uses a "black and polished brass" time machine to gain mechanical control over time as well as return to the present to bring back his story and assess the consequences of the present on the future. Wells was a graduate of the Imperial College of Science and Technology, and scientific language permeates his discussions. Many believe Wells' book to be the first story about a time machine, but seven years before 22-year-old Wells wrote the first version of The Time Machine, Edward Page Mitchell, an editor of the New York Sun, published "The Clock That Went Backward."

One of the earliest methods for fictional time travel didn't involve a machine; the main character in Washington Irving's "Rip van Winkle" (1819) simply fell asleep for decades. King Arthur's daughter Gweneth slept for 500 years under Merlin's spell. Ancient legends of time distortion are, in fact, quite common. One of the most poetic descriptions of time travel occurs in a popular medieval legend describing a monk entranced for a minute by the song of a magical bird. When the bird stops singing, the monk discovers that several hundred years have passed. Another example is the Moslem legend of Muhammad carried by a mare into heaven. After a long visit, the prophet returns to Earth just in time to catch a jar of water the horse had kicked over before starting its ascent.

Time travel is possible Today, we know that time travel need not be confined to myths, science fiction, Hollywood movies, or even speculation by theoretical physicists. Time travel is possible. For example, an object traveling at high speeds ages more slowly than a stationary object. This means that if you were to travel into outer space and return, moving close to light speed, you could travel thousands of years into the Earth's future.

#### javayathzee

##### New Member
There are several laws of physics that show that you can't travel as fast as the speed of light. If you could though (according to Einstein) time would stand still.

#### FalseHope

##### Active Member
That would be amazing. Although, you would think, that you would get some sort of brain damage or something, from going so fast. Something else besides time stopping would have to happen!

#### winlux

##### New Member
He he, tha above post just cracked me up)

All the contributed points are well taken. However, just assuming the issues with G, time-dilatin, orbiting etc were non existent, what do you think happens when one travels faster than light?

Well what happens... see... then... in conclusion MORE HAPPY PEOPLE. It's S**T loads quicker getting to the pub!

#### FalseHope

##### Active Member
Quicker? It would be faster than a blink of an eye!

#### mender42

##### New Member
Well it seems that due to some new research and studies they are even rethinking that whole E=MC2 thing, apparently even Einstein had some second thoughts. One of my favoite "reads" is Discovery Magazine, this two page article worth reading at least the last two paragraphs. I think that says it all..

http://discovermagazine.com/2008/mar/10-einstein-didn.t-grok-his-own-revolution/article_view?b_start:int=1&-C=

http://discovermagazine.com/2008/mar/teleportation-very-possible-next-up-time-travel

Anything is possible!. :hsughr: See you at point B! Or C or :hsughr: Hey...where's that pub?

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#### kkenny

##### Active Member
I still think if you could travel at the speed of light the huge g forces instantly kill you.

#### Zdroyd

##### New Member
That would be amazing. Although, you would think, that you would get some sort of brain damage or something, from going so fast. Something else besides time stopping would have to happen!

Well one litte thing that would happen besides time stoping is;

You Would Cease To Exist!

#### mender42

##### New Member
Ouch my ears... no need to shout! It's all relative anyway!

#### Smith6612

##### I ate all of the x10Pizza
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Well one litte thing that would happen besides time stoping is;

You Would Cease To Exist!

AKA Divide by Zero

#### Mekryd

##### New Member
You would dissolve into some quantum particle or another before hitting light speed.

#### de.monkeyz

##### New Member
I think that if you did travel that fast when you went to a store, you'd either transform yourself into a sentient being and become pure energy, or because your reactions arnt soo good, you'd splatter yourself agains the wall, since you forgot to stop >.<

#### FalseHope

##### Active Member
Woah, your post just gave me an idea. If you traveled at the speed of light, you would be able to get whatever you want, at a five finger discount. Although illegal, it would still be possible. You could steal from a bank, or push a car to your house, now, how amazing would that be?

#### mender42

##### New Member
I think that if you did travel that fast when you went to a store, you'd either transform yourself into a sentient being and become pure energy, or because your reactions arnt soo good, you'd splatter yourself agains the wall, since you forgot to stop >.<

The answers we find I hope will not always be walls! just think even walls have doors. Use doors, less painful. Now where is the door?

I'm no expert but isn't this somthing like Shrodingers Cat? That is all things (states)are possible...

#### Zangetsu

##### New Member
i think this page has most of your awnsers http://en.wikipedia.org/wiki/Faster-than-light but if you're asking me if it would be possible to travel at the speed of light my awnser would be no not yet, and why well we dont have the technology jet

#### like2program

##### New Member
<nerd>Because you are surrounded by molecules(air) you would create enough friction to destroy yourself, the earth and the moon. For the few seconds you were still alive however, you wouldn't age and you could do whatever you want as long as you stay at the speed of light....</nerd>

#### FalseHope

##### Active Member
What if you were like someone from the movie Jumper, and went through wormholes, I am pretty sure they go faster than the speed of light.

#### BorderLineSigs

##### New Member
i believe that you would end up flying....because the amount of force you would be exerting on the ground to BE ABLE TO MOVE THAT FAST!...if that doesn't happen i believe you would melt because of the heat you are producing from your speed...AND you wouldn't be able to go that fast for very long (if at all) because you wojuld be using up so much engergy!

#### FalseHope

##### Active Member
Wormholes, that's how we could travel faster than light! They'd protect us from whatever, heat and what not.

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