Back to a little science!!! The real reason why we may not be able to travel faster than light.


Most folks know about the speed of light and all of the problems with trying to build a ship that could travel at that speed.

1. As you approach the speed of light the mass of your ship would approach infinity.

2. Time dilation. Even if you were able to build the craft that could do it, from your perspective, you would never process the second or millisecond where you reached the speed of light.

3. It would take an infinite amount of energy to reach the speed of light.

These barriers are the result of Einstein's Theory of Special Relativity. But even Einstein gave us an out when it comes to traveling faster than light. The trick is not to move an object through space. But to move the space the object is in. Einstein's laws say nothing about space itself being moved. So there are models and theories now about how to build a warp bubble, allowing for this type of travel.

But there is also the possibility of constructing or using a wormhole. You could have a path through spacetime that connects two distant points. And the wormhole through spacetime would give you almost instantaneous travel no matter how far away these locations are from each other.

Then lastly, there is teleportation. We could build a device that could analyze a person's body at the planck length of spacetime. Each planck unit could be copied and transported via a form of "entanglement" to a distant location.

But all of this could be moot.

Because of the one thing we have overlooked for decades;

FTL travel breaks casuality.

We could literally break the universe by building a successful FTL ship or simply by building a FTL message system. Consider that if we built a ship and traveled to a distant location. The ship doesn't even FTL capability. Let's just say it went at 90% of the speed of light. If we started off on a distant journey, we would experience time dilation. According to Einstein, our "clock", our time", would tick slower than a person's time here on earth.

Now imagine if a person wanted to send us an instantaneous message using some FTL messaging system. A person could send a message to us, four hours after we left the earth. That's four hours from his/her perspective. We would receive that message approximately two hours into our journey. Actually it would be slightly less.

And here is the important thing. We receive the message two hours into our journey. . .but message is received in the past for the person on earth. Remember, our clock is moving half as fast as a clock on earth. So we could reply. . .and our reply would travel back in time from the perspective of anyone who is still here on earth.

They would receive a reply to a message, that they never sent. Or more accurately have not sent yet. You might say what's the big deal? What if the message says. . ."do not send any messages, it is a matter of life or death".

How could we receive a message that was never sent? And the paradoxes just get worse from there. If you are traveling faster than light, you can go to a distant world and come back before you left. You can cause all manner of nonsense because the rules of casuality do not apply anymore.

Once I read about this, it kind of messed me up. I am a big fan of Star Trek.

Back to a little science!!! The real reason why we may not be able to travel faster than light.
Back to a little science!!! The real reason why we may not be able to travel faster than light.
Back to a little science!!! The real reason why we may not be able to travel faster than light.
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Most Helpful Girl

  • Daniela1982

    How can you even send a message to someone who is traveling at faster than light speed when the message is only traveling at the speed of light. It could never catch up with you. Not only that, traveling that fast, if you even hit a grain of sand it would create catastrophic damage and possibly destroy your ship.

    Is this still revelant?
    • Also you couldn't teleport anyplace without having a receiver on the other end.

    • We didn’t send a message to someone traveling at light speed. We sent an instantaneous message. That is much faster than light speed. And we did to a ship that was traveling about 90 percent of light speed.

      Why respond to a take you didn’t even bother to read?

    • So dull. All you have to do is send a ship with all the necessary equipment, supplies, etc. needed. It could navigate the dangers of space without the need to sacrifice human beings.

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Most Helpful Guy

  • goaded

    I'm still trying to get my head around the argument, but I'd just like to mention a really good book called Timescape, from 1980. I think you might enjoy it.

    Is this still revelant?
    • goaded

      Don't read the Wikipedia page, it's full of spoilers!

    • goaded

      "If I move at 90% the speed of light. My clock will tick at a fraction of yours. And what may be six hours for you, will be two hours for me. If send me a message, I will receive it in your past. And when I reply, it will be in your past."
      But isn't the Earth moving away at 90% the speed of light, from your point of view? If you looked back at the Earth, days would last 72 hours.

    • Yep, the earth is moving away at 90% of the speed of light. But we are talking about how time clicks in our reference frame. If you had a transmission that showed you the passage of time on earth, you would wonder why everyone is moving so fast.

      So let's get the correct time scale, first.

      At 90% of the speed of light, 72 hours on earth, would mean about 32 hours on the ship.

      If we could send a simple message instantaneously or faster than the speed of light, that message would be received by the ship in what the earth would consider to be the past.

      You have to understand that for every tick of the clock on the ship, several ticks are pass on earth. So let's just say four hours passed on earth. . . well only two hours have passed on the ship. This transformation is a two way street.

      Think about geometry. Imagine a X-Y axis. The Y axis goes straight up. The X axis is horizontal, left to right. Now imagine drawing a line at a 45 degree angle from the starting point of the X-Y axis, point zero all the way out effectively diving the upper-right quadrant into two.

      Back to a little science!!! The real reason why we may not be able to travel faster than light.

      If I set a scale of for the Y-axis. . . and set some arbitrary increment for hours. Then marked off four hours at some point going up. . . I could draw a straight horizontal line going over to the line drawn at a 45 degree angle.

      I think we can agree that if we measured from 0 to 4 on the Y axis. . . that would be shorter than where we intersected the line drawn at a 45 degree angle.

      This is to illustrate that time passes more quickly on the Y-axis. And on the line drawn at 45 degree, time has passed more slowly.


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What Girls & Guys Said

  • NYCQuestions1976

    I remember being a kid and trying to imagine what it would be like to travel at the speed of light, or even faster. I had a really old set of encyclopedias that my grandmother gave me in the 1980s. I believe they were from the 1950s. There was a rudimentary section in one of them on the "prelude" to this. If I remember, it was written by a physicist and/or astronomer, from Iceland maybe? He described a person/people traveling away from Earth at the speed of light for 40 years, and then turning around and traveling back to Earth. He theorized that something like 10,000 or more years would've passed on Earth in those 80 years traveled by that person/those people. I grew up watching Star Trek (mostly The Next Generation) and Star Wars, and often wondered if his theory was correct, and if it really could be realized, would it be worth leaving everyone you know behind to "boldly go"? Almost like experiencing the "curse" of immortality. You're alive, you come back, and everyone you ever knew is gone. Sort of a similar premise to Futurama, I suppose.

    • Well, in Star Trek especially, they propose faster than light travel. Not just travel close to light speed. We know if you travel close to the speed of light, you will experience time dilation. We know this because you phone wouldn't work if time dilation didn't exist. The time devices on satellites have to take it into account when working with GPS systems.

      But in Star Trek, a ship can travel from here to Alpha Centuri in a couple of hours.

      And the fact that FTL can break the casual connections is the problem. As physicists explain, if you travel at light speed, your speed is 0. Basically, you experience no change in time.

      But if you go faster than light, you will experience moving backwards in time.

    • I guess experiencing time minus at warp plus would cancel the perceived "accelerated" passage of time on Earth, if that theoretically really does happen? Eventually, only time will tell.

      Teleportation is another important technological goal, and one I would argue we should be focusing on even more than warp travel. Along with the obvious applications in/for space, being able to teleport on Earth would eliminate commuting and atmospheric pollution. Of course you wouldn't want to accidentally teleport yourself to oblivion. The scene from Wrath Of Khan (the interaction between Kirk and McCoy) on the Regula One teleporter still makes me laugh:
      Of course it's a great movie with many great lines. 40th anniversary also.

    • Well that's the thing engineers are trying to address with warp travel. Because just traveling near light speed would kind of suck in terms of time passage on earth. You would go on a mission and by the time you got back, your children would have passed away from old age.

      Teleportation is something viable. You could send the appropriate equipment to a distant system, then activate it. But it wouldn't like Star Trek's teleporters. They only transport limited distance and it appears to do it at the speed of light. Because they are turning your mass/body into energy, transporting the signal, the reintegrating you.

      The teleportation I talked about is actually instantaneous. And it uses cloning. If we could create a machine to clone every single planck unit of your being, it should still be you when you materalize on the other end.

      Brian Green explains it best.

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    I can't keep reading.
    Why would time stop being just because you reached the speed of light?
    All things being relative, you should still experience the passage of time, if you didn't then how would you travel any distance?
    Time is required, even for light, to get from one place to another.

    • You are kidding right? The fact that time stops at the speed of light isn’t a hypothesis. It is a proven fact. We only have to look at a photon. We only have to look at what happens in particle accelerators. And all of our physics in the classical realm is dependent upon Einstein’s discovery. Your speed through spacetime must always equal the 186000 miles per second. And if you are moving through space, your movement through time must be conserved.

    • RACSKC0B

      I'm not saying that it won't slow down significantly, relative to someone else, but it can not completely stop. If time stops for things traveling at TSL, they would be trapped, forever traveling at TSL.
      Relative to someone on earth, yes, you would experience significantly less time. But it can not be 0.

    • Of course it completely stops. Again, are you kidding? Have you found the greatest scientific discovery since Einstein and are just hanging out on the internet instead of raking in billions? Time stops completely at the speed of light with respect to the passenger. From the outside we could look inside the vessel and see the clock stopped. To us everyone inside would be frozen.

      And from their perspective they would not notice a thing. They would simply know that at light speed all their journeys happen instantaneously. Einstein is no joke. He said that momentum must be conserved. You are constantly moving forward with respect to time. If you move through space at the speed of light you cannot have any momentum through time. It is a fact of life. Where have you been for the last 120 years? You only have to watch the first two minutes.

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  • Adam1978

    No your wrong if I leave earth four hour before I get sent a message. I will have been traveling for over four hours when it reaches me. When I reply to this message it will take slightly longer to send it back. Since I have traveled further away. So the reply will arrive much later from the person on earth view point. Time is relative. No paradox on either end they both experience the same order just within different time frames.

    • Haha! No dude. You didn't read the scenario.

      If you travel at 87% of light speed, you will experience time dilation of one half. So if if one hour passes on earth, you will experience a time passage of 30 minutes.

      Note; you will never know how quickly time passed on earth. You are in your own reference frame not noticing a thing.

      Here is a time dilation calculator. 87% of the speed of light is 261,000 km/s. If you punch the numbers in you will see your relativistic time is twice that of earth time. And the most important part is, having an FTL messaging system. FTL means faster than light.

    • Adam1978

      Doesn't matter if you have a ftl message system, it still arrives in the same order you put the message into them. You just reduces the message travel time. So you will never get a reply for a message before it's written. Independent of what direction the ship is traveling compared to the observer.

    • This is hilarious. . . you are stating your error without realizing it. Let's say you have a sub-space messaging system just like on Star Trek. If you notice, Star Trek has instant communications. The problem is that the reference frames are never reflected on television.

      If a person is stationary sending a message, then that message will arrive in their past with respect to the person traveling at relativistic speeds.

      This isn't my theory. The was created and proven over 100 years ago by a guy named Einstein. And the theory again, is called "The Special Theory of Relativity".

      You are not getting time dilation.

      But if you don't understand physics, it is kind of hard to grasp.

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  • AviatorTom

    Interesting post, thank you.

    My take on the whole travel faster than light (FTL) thing is that we humans don't really know.

    Time is not a universal property, it's created by humans. Speed involves distance per unit time, and is therefore also a human created measurement, not a universal property. The speed of light as a constant is, therefore, something created by humans, and the human-created limitation that one can't travel faster than the speed of light is simply based on the fact that the equations (created by humans) don't support it.

    Like you, I too am a Trekkie, and the concept of a warp bubble created by warp engines could simply be an expansion of human-created physics to what the universe actually supports.

    Not that long ago, humans said travel faster than the speed of sound was impossible, then Chuck Yeager in his X-1 did it. Maybe 2063 will see Zefram Cochrane travel at warp speed and prove that FTL travel is possible.

    Helpful 1 Person
    • Oh, I definitely agree, we don't know. We haven't scratched the surface yet. We created a microscopic wormhole. We have seen Quantum Entanglement. The rest is nothing but conjecture and theory. We need models to test the different types of drives that are just concepts now. There is so much to do. But we are getting more and more investment in the science because folks are seeing this as a business opportunity.

      Of course, Time is a concept we created. But we did not create casual relationships. You see when I talk about the speed of light, I really mean the speed of information or. . . of casual relationships.

      Casuality cannot more faster than the speed of light. The fastest speed, we can even know about an event, is the speed of light. To know something faster than that is to break casuality.

      That is the concern.

      Who knows? Maybe the universe steps in and does something to block knowledge or transmissions. Maybe something happens similar to the speed of light. Where before casuality is broken, a barrier is erected.

      I dunno.

      No one does. But we won't know until we start building actual models and testing this stuff.

  • Wade12345

    The real reason you can't travel faster than light through space is the debris you will hit from space dust and gas in space. The kinetic energy from hitting a piece of dust the size of a grain of sand is like a gallon of gasoline exploding ideally, which would destroy your ship.

    • There are FTL alternatives that address that. I posted about wormholes and teleportation.

      The problem is with causal connections. We live in a universe of cause and effect. With FTL, you can have effects before causes.

  • Sarahplus2

    No making a Jump to light speed to evade Imperial warships?

    Funny 1 Person
    • Star War dudes are always hurt when we tell them that warp speed is way faster than light speed.


    • Sarahplus2

      Hypothetically, how would aliens be getting here if they were visiting? Interdimension?

  • captain_voidwalker

    This is also why black holes break causality. Anything beyond the event horizon is traveling faster than light. Dpace is so irrevocably twisted past the event horizon that ll directions even the one you enter into the back hole at, now point directly at the singularity. Even if you could travel faster than light you can never escape a balck hole since all of space and time are now unidirectional.

    • Wow, you posted some stuff right there. I want to do a take on black holes. But I want cover neutron stars first.

      It is still an amazing point that once you past the event horizon, spacetime (as you said) is flowing into the black hole faster than the speed of light.

      The thing I have problems visualizing is that in the black hole space and time swap roles. Do you know of a diagram or a visualization that explain that?

  • exitseven

    yes, it is true that from a space traveler's perspective time moves more slowly but externally it does not This only effects the traveler and not the whole rest of the universe.

    • I am not understanding how this disproves anything.

      1. The universe is filled with an infinite amount of reference frames.
      2. Each one of those reference frames has its own clock, ticking at its own rate.
      3. The point is that time is not universal. The speed of light is. So the universe is bending and stretching in all of these different areas to keep the speed of light constant.
      4. That's why when you travel close to the speed of light, then someone sends you a message faster than the speed of light, it breaks casuality.

      Now we can really wreck this, by talking about actual FTL travel.

      Tell me @exitseven. . . if I move at the speed of light, what do I perceive about my speed?

      Let's begin there.

  • kao118

    Also because c is the ultimate speed. It exist but we can’t achieve it. I appreciate this post as a physics lover, although im curious as to why you posted it on this site.

    • You could pm me. But if you look at my history you will see I have a habit of posting about physics. The funny thing is I doubt you confront the folks who constantly post about politics. Which have nothing to do with relationships or dating.

    • kao118

      I stay away from politics by principle. But I think there’s a section for politics. Either way, I glad you’ve posted about it, nothing like physics to brighten up my day and surprise me, especially on such an intriguing topic,

    • There is also a section for science and technology. So look out for my takes on neutron stars and black holes.

  • msmissydc

    So to your last part. No we can never arrive before we left. We moves slower true time yes, but still allways forward. We can travel into the future but dont have a way back.
    About the message part: It would be a theoretical concept that is at first not related to the other parts. Because that would actually need FTL capabilities. Maybe not for particles but for information. At this point in time as far as I know there is no such thing as a theoretical concept, that this could be possible without disproving relativity.

    • We move forward at different rates. You are not understanding this.

      Time dilates when objects are in motion, with respect to objects that are at rest.

      If I move at 90% the speed of light. My clock will tick at a fraction of yours. And what may be six hours for you, will be two hours for me. If send me a message, I will receive it in your past. And when I reply, it will be in your past.

      I didn't travel backwards in time from my perspective.

      I traveled to your past.

      And all you have to do to understand that is to use the Lorentz transformation to switch to my reference frame.

      Start at 10:00. . .

    • msmissydc

      This still implies that there is FTL Travel for information.

    • It isn't implying that all.

      Did you read mytake?

      The point was we were always taught that if we only figured out the rules for FTL, we could live like Star Trek in the future.

      But that may not be true. Because we would be breaking casuality. We only know of an universe where cause must proceed effect.

      Now maybe that is the case or maybe it isn't. Or maybe casuality is preserved in some other way. We simply do not know. I was just giving an example of the possible consequences of FTL travel or FTL messaging.

      It is basically the same thing. Because we are talking about the fastest possible speed of usable information.

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  • monkeynutts

    You should watch Red dwarf if you have not already, it's loaded with pop culture references, and comedic scientific conundrums. Very funny.

  • RealMarek

    I think the way time dilation works, if you were able to send messages in a warp bubble (instantly) it would work like this:

    Earth-based person sends message at four hours into the journey according to earth time, the person on the spacecraft receives it two hours into the journey according to spacecraft time. If the space-person replies two hours later (total of four hours according to the spacecraft’s time), the earth-based person receives it at eight hours after launch according to earth time. The message doesn’t go back in time, the gap in elapsed time between the spacecraft and earth widens the longer the journey continues. The perceived time between messages on earth is greater than the perceived time between messages on the spacecraft.

    • You seem to be talking transmissions happening at the speed of light. We are talking about instantaneous communications. I ask this of everyone who questions this logic which is based on Einstein. If you send a message at the speed of light, from the perspective of the message, how much time elapses.

      Or let’s make this even worse. Let’s say you go on a mission to Proxima Centuri, which is 4.5 light years away. When you engage your engines to travel at light speed how much time does it take you? And of course, from your perspective. Not anyone else’s.

  • 1stupidrobot

    Realistically, the reason we (humans) will never achieve faster-than-light-speed travel is that we are going to cause our own mass-extinction event in the very near future.

  • msc545

    Actually, if you reach the speed of light, time *stops* - with unknown but probably unpleasant consequences.

    • Well, that is another issue altogether. Could human beings even survive being in a ship that could come close to the speed of light? The answers are all over the place.

    • msc545

      Maybe not. The gravitational issues and changes in mass would probably kill us.

    • There was a prediction that said at around 80% of “c”, the change in mass would kill us. But there are other methods for faster than light travel.

      So that question about casuality is still an issue.

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  • Luopio27

    I recomend Evacuate Earth documentary.

  • Anonymous

    Wow you're so smart op

    • I just wanted to see about having a conversation just using rational thinking, science and logic, to see how folks here respond.

      It ain't going so good.

    • Anonymous

      I think it's because you're such an asshole in your usual posts that anyone smart enough to care warp drive has either blocked you or is going anon.

      Reflect on that you sanctimonious twat..

    • Well, you don't have me blocked.

      So that must mean you are stupid as fuck.


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