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# Why does traveling faster than the speed of light mean time travel?

Why does traveling faster than the speed of light mean time travel? Lets say I was on earth and I shined a strong laser towards a person living on neptune( I know it isnt possible but please work with me here!) , and then If I traveled to neptune in one second, how would that make me travel through time? Would I just be in the same location as the Neptunian?

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### 9 Comments

• aaron says:

i heard that if your in subzero temperature time stops

• Saint Onle says:

This comes from Einstein’s theory of relativity. Specifically special relativity. Einstein showed that because the speed of light is constant in every reference frame, the time measured by observes in different reference frames is different. The equations show that it is impossible for a massive object to travel faster than the speed of light. All massive objects must travel slower than the speed of light. However, they also imply that an object traveling faster than the speed of light (and with imaginary mass, whatever that means physically) would travel backwards in time. This is were it comes from, Einsteins equations for special relativity.

As for you second question, you can’t travel there in one second. If you were able to travel faster than light, by just accelerating, then you would get there before you left. If you did some type of wormhole thing, then nothing would happen.

I don’t know what you mean the same location as Neptunian. I assume that if you flew there, you could land wherever you wanted.

• Steve Biski says:

Traveling at the speed of light does not represent time travel. In fact, according to the theory of relativity, mass moving at the speed of light is impossible. As you approach the speed of light, according to the theory, your mass would increase, and the force required to keep accelerating would become larger. If you ever neared light speed, you would achieve infinite mass, and require infinite amounts of force to keep moving, thus making traveling at light speed impossible.

• Kiki says:

traveling at the speed of light doesnt necesarily mean time travel. traveling at the speed of light just means you can move at the same rate that light does, but depending on where you are, it can mean “going back in time” if you will. it takes the light from the sun around 7 or 8 minutes to reach earth. so lets say you wanted to go to mercury, if you traveled at the speed of light, it would mean that you would be going about 7 or 8 minutes ahead of time, for the light to reach mercury (hopefully this makes sense).

now if you went to neptune, you would be going “back in time” but only because it takes the light to reach neptune longer than it does for earth.

now if you went to a different galaxy, you would be traveling at the speed of light (duh), but take into consideration, that what we see in the stars here on earth, can be 5 billion years older than what it truely is. so if you went to a different galaxy, at first it would seem that you are going back in time, when really you would be going forward, because the closer you get to the galaxy, the shorter amount of time it takes for its light to reach you. so the galaxy would seem to be changing fairly quickly. so yes to a point, travling at the speed of light could mean going “back” or “forward” in time.

hope this helped.

Your Welcome

• Jeremy says:

regarding “F H”s answer- Time is just a concept, an idea. it does not exist, in my mind its an attempt to understand existence. therefore that E=MC2 is not true for the time part.

• Bivek says:

It is called time travel because different planets have different time period to be consider as a year. If you go to neptune and stay there for 3yrs(neptune time) and come back to earth then you’d not passed 3 year of earth, so you are not 3 year old for earth comparing to the time you pass in neptune. And speed of light is not affected by friction so light has highest speed in this universe.So traveling faster than the speed of light mean time travel. Hope it helps.

• BD says:

Well, because of the theory of relativity, the faster you go, the slower time is for everything around you. Also, just because you’re traveling faster than the speed of light, it doesn’t mean that you’re time traveling. That’s a movie cliche.

• Pathankrious Shark. says:

the idea is that the faster you are the slower time moves, so if you went light speed for 10 years, it probably would be 50 years earth time…so if you went faster, time would move slower.

• F H says:

It’s believed by some that as you accelerate time slows. Once you reach light speed 186,000 miles per second time would stop if the theory is correct. E=MC2