How to travel faster than light

How to travel faster than light

You don’t have to be much of a science enthusiast
to have heard that you can’t go faster than light. Well, I’m going to tell you at least one
way that two real, honest-to-god objects, that exist in our universe, can move away
from one another faster than the speed of light. Now, don’t get super excited. I’m talking about ways this can happen without
breaking the laws of physics. To be ultra clear, I’m not talking about
something that will lead to this. Or this. Or this. We’re gonna have to go right to- ludicrous
speed! Ludicrous speed? Sir, we’ve never gone that fast before! I mean, I totally want to know how to go ludicrous
speed. But, unfortunately, and I hate to have to
tell you- these are all fiction. So, if it’s possible to go faster than light,
what exactly do I mean by the speed of light? I mean the speed of light in a vacuum in a
location where spacetime is not bent or changing. Under those conditions, the speed of light
is about 186,000 miles per second or, for the metric crowd, precisely 299,792.458 kilometers
per second, or fast enough to circle the globe 7.5 times in a single second. Light is like really, really, fast. When physicists use the symbol “c” to
denote the speed of light, it’s this speed that they’re talking about. So, how can you go faster than light? I can think of three examples, although they
all aren’t quite what you probably think. The first is cheating. When light enters a transparent medium like
water or glass or something, it slows down. In glass, light travels at about two thirds
the speed it does in a vacuum. In water, it’s about three quarters. You can see the effect of this change in velocity
by simply sticking a pencil in a glass of water. The pencil doesn’t really bend, but appears
to because of this effect. While light slows down in a transparent medium,
other particles do not. That means that if you shoot an electrically
charged particle like an electron or a muon traveling at near the speed of light at that
same medium, the charged particle travels faster than light in the medium. Cool, huh? When this happens, the charged particle emits
blue light like you see here. This light is called Cherenkov light after
its discoverer, Pavel Cherenkov. Explaining just how Cherenkov light is formed
is, well, tricky- and maybe I’ll make a video about it. But the blue light you see here proves that
it is possible for objects to move faster than light in a transparent medium. In this example, the light is formed when
radioactive material emitting highly energetic particles is immersed in water. It’s all way cool. So that’s maybe a cheat. Particles move faster than light, but it’s
not because particles got faster, but because light got slower. Are there other examples? Well there is another instance of information
traveling faster than light which I’ll mention only briefly and this involves a topic called
quantum entanglement. Quantum entanglement is a category of quantum
mechanics, which is known for its bizarre predictions- cats both alive and dead and
all that. It is not possible to explain it in detail
here. That would actually require not just one video,
but an entire series, but here I can give the highlights. In quantum mechanics, probability rules. Anything that is possible can happen, governed
by the probabilities of that particular situation. As an example, a subatomic particle can have
a spin of plus or minus. You can’t know which of those spins it has,
until you actually measure it. It’s important to understand that this isn’t
a simple case of ignorance. It’s not that the spin is plus or minus
and you just don’t know. It’s both plus and minus and it becomes
plus or minus when you measure it. Now suppose you take two particles and set
them up so that they have opposite spins. If one is plus, the other is minus, and vice
versa. When physicists do this, they say that we’ve
entangled the two particles. You can’t know in advance which particle
is plus and which is minus. You then separate the two particles by a large
distance and look at one of them. Say you find that it’s a plus spin. If you look at the other particle, you’ll
find it’s a minus spin- every single time. And this will be true even if you look at
the second particle so quickly that you see it before a signal arrives from the first
particle traveling at the speed of light. Einstein called this a “spooky action at
a distance” and it says that the information in quantum mechanics can travel faster than
light. Nobody understands this, but it’s well established
and it’s just a true effect. So that’s a case of something traveling
faster than light, but you can’t use it to send a message and it’s still not the
same as an object moving faster than light like the Starship Enterprise or the Millennium
Falcon. So let’s talk about a third situation where
things actually can travel faster than light. And that’s the expansion of the universe. Now I should be cautious. When you hear people saying “the universe
expands faster than light,” it’s obviously a statement that requires some care, because
your first question should be “what does that mean?” Well, obviously the universe can’t mean
our planet, our solar system, or even our galaxy. After all, none of them are expanding much,
if at all- and certainly not at the speed of light. In 1929, American astronomer Edwin Hubble
combined measurements taken by several people and found that distant galaxies are moving
away from Earth and, the further away they are, the faster they’re moving. This is now understood to be evidence that
the universe is expanding. Using modern numbers, a galaxy a megaparsec
away is moving away from us at 70 kilometers per second. A megaparsec is million parsecs, which is
3.26 million lightyears by the way, but astronomers use megaparsecs, so I will too. If a galaxy a megaparsec away is moving away
at 70 kilometers per second, a galaxy two megaparsecs away is moving away at 140 kilometers
per second. Three megaparsecs means 210 kilometers per
second, and so on. So we know that the speed of light is 300,000
kilometers per second, so we can figure out how far away we have to go to have a galaxy
moving away from us at the speed of light. That turns out to be 4,296 megaparsecs or
just shy of 14 billion lightyears. This means that the surface of a sphere, centered
on the Earth, and with a radius of about 14 billion lightyears is moving away from us
at the speed of light. It also means that bigger spheres are moving
away from us at faster than light. A sphere with a radius 28 billion lightyears
across is expanding at twice the speed of light. So, what does this mean? Does it mean that there are galaxies moving
away from us at speeds faster than light? Yeah. Yeah, it does. Of course, it also means that we can never
see them. If objects move away from us faster than light,
then that means that light emitted by them never get to our eyes. So, we can never see the light emitted by
anything currently further away than 14 billion lightyears. The true number is a little different because
of details of how the expansion speed has changed over time. To get the number right means we have to take
a more nuanced approach than I’m doing here, but those details don’t change the big message. It’s also incredibly important to be super
careful about how we envision it. The reason is that it’s not precisely accurate
to say that these galaxies are moving away from us faster than light. Yes, the distance between us is increasing,
but it’s because space is expanding, not because the galaxy is moving away in space. It’s kind of like putting a rubber duck
in a river. The duck isn’t moving as far as the water
is concerned. It’s the water that’s carrying the duck
away. Or like drawing dots on a balloon that’s
inflating. The dots don’t move on the surface of the
balloon, but the distance between them is increasing because the balloon is stretching. So it’s entirely fair to say that there
exist galaxies that move away from us faster than light, but only in the sense that the
expansion of space makes it happen. Those galaxies are stationary, or at least
nearly stationary with respect to their own space. They’re not moving through space. I’ve described three examples of the phenomenon,
but none of them are something that those of us who hope to explore the cosmos would
like to see. According to our best understanding of the
laws of physics, light obeys the ultimate speed limit. Now, our understanding of the rules that govern
the universe are constantly improving and it’s okay to hope that we’ll discover
some new principle that makes it possible to go faster than light. Although unlikely, it may be that we will
eventually find some new phenomenon that changes our prospects for exploring the galaxy, and
then, and only then, we will have finally figured out a way to go- LUDICROUS SPEED! People say that it’s impossible to go faster
than light, and, as a practical matter, it’s probably true. But we’ve learned in this video about a
few ways in which we can at least kind of break that rule. So now you have some tidbits to use at your
next cocktail party. You’re welcome. If you like what you’ve seen, remember to
be sure to like, share and comment. We want to know what you think. And, as always, remember- physics is everything.

100 thoughts on “How to travel faster than light”

  • Let me move faster, away from you than a bullet from a gun pointed at you while I pull the trigger . suggestion to you, move.Or , that bullet will shoot me.

  • It does means that “we” are moving at speed of light for an observer situated on that far far away galaxies???

  • Colby Wolford says:

    But wait, does this also mean that we here on Earth are moving 2x the speed of light away from an observer on a planet 28B Light Years away from us?

  • I think that it is impossible to get the same speed or even higher speed because if this were the case we couldnt obviously See it because the Light cant catch it and reflect it

  • Surprised you didn’t mention the Alcubierre drive at the end. It might work with dark energy, which seems to warp or expand space at a rate > c

  • The speed of light isn't rely all that fast if it only orbits the earth 7.5 times a second you could notice that at night

  • Ah, just a moment. Those galaxies at 28-billion light years distance that are receding at twice C. "We will never see them" because the light won't reach us? Since Einstein we've known that the speed of light is constant, regardless of the speed of its source. The light from three objects, all placed at 28 billion light-years from Earth, will reach the Earth simultaneously even if one is stationary, the second is receding, and the third approaching … at any speed, in any direction. What am I missing? I would really like a clarification on this. Perhaps physics has changed since my old school days. Can the expansion of space really overcome the speed of light to the point that from our frame, light stands still … or even moves backwards?

  • I petition NASA to label any of their future space ships going over a certain speed to be considered going "Ludicrous Speed". This must happen.

  • If the universe is expanding, and space is a fabric that stretches. Wouldn't it all retract back to a single point in the very center and explode causing another Big Bang?

  • If the speed of something can be converted into how far it travels over a period of observable time then the speed of the object is variable. The speed of light is variable and is not a speed limit. If light slows then objects can match or surpass it's velocity.

  • Hexacaust Archon says:

    Dear Dr.Don. The thing that is faster than both light and information is explosive diarrhea. Because when it happens at night, one is running so fast to the bathroom they neither get to turn on the light, nor do they get to think about it!

  • QLCL Corporate says:

    I'm surprised that he ain't mention the tachyon al though a hypothethical particle but that is just because no-one knows how to detect it

  • If the universe is 92 billion light years across and its only 14 B L.Y old, then stars and galaxies must be moving at 3 times the speed of light. Simple maths.

  • Edward Biskind says:

    Is it possible for two separate particles to each move from a single point 180 degrees from each other at the speed of light? Then what would be the speed of the two particles with respect to each other?

  • This saying that we can never see thing moving away faster than light doesn't make any sense. Unless they drag their light with them… Light shot away from a location would eventually get here.

  • not tru—-sorry.
    scientist in ger reached 2.1x Light speed in a lab with one single atom….soooooooo….there is a way 🙂
    And Einstein id not want to believe that " Spookie Action " so, were did you get that einstein believed that fact ? in his time there was no way to figger this out… ??????
    Sorry…a hole lot of " Miss information "

  • Thomas Koehler says:

    is there only one center of universe expansion, in all of existence? Are there no galaxies expanding away from other centers of expansion? If there were, some of them would be expanding in a direction towards us, wouldn't they?

  • Brendan Greene says:

    Speculation – that space is expanding at speed of light – we can't see it to measure it. The fundamental particle light photon – nothing travels faster – hence why it is used as a constant. You might as well say – fire two photons 180 degrees from each other at speed of light – state that one is actually stationary – as you have defined that as frame of reference – the other is travelling at two times the speed of light – it's this sort of poorly explained bunkum that just fuels "fake news" and "conspiracy theories".

  • Doctor Too-Much says:

    so theres no energy transmitted or converted to any mass by the spacetime expansion itself and therefor the masses arent moving faster or accelerate?

  • 8:16 according to the theory of relativity the speed of light is same in all reference frames
    So,why will not light reach the earth if it is projected from a frame of velocity 2c as light must not have any initial velocity -2c according to the earth reference frame and velocity would always be c?
    someone please explain this to me 'cause I'm just a college student

  • The Sparkle Zone says:

    5:54: Wait, why can't you send a message like that?? If you have a pair of particles with polar charges, couldn't you convey data like a computer using electrons to make binary language?

  • I just need to have a ship that travels slightly faster than half the speed of light (we'll call my ship matter A). Then i get another ship and give it to my friend, one just like mine (we'll call his ship point B). We then head off in exact opposite directions from each other and, voilá, matter A is moving away from point B faster than the speed of light 🙂

  • James Wienbarg says:

    IN the current theory of the speed of light, we have the reason we don't get faster then light from an equation that makes an atom as hevey as a space ship.

  • This is how the intelligent brain wash the non intelligent . All that high tech learning to out smart people with no high tech learning. Oh my who really believe this crap. Hey who is crazy ??

  • Zom Bee Nature says:

    Could you be more stilted, over-act more, flap more chins, and rasp your microphone more? I want to have the ultimate repulsion experience.

  • Traveling the speed of light will not work when going to the nearest star. It would take years! You have to use warp drive!

  • Thank you. I'm underprivileged and have a learning disability. But, am fascinated with the content of these mini lectures. Please teach more.

  • There is a 4th way to travel faster than light, buy using light that is moving at its "normal" speed, namely c.

    The answer is that SHADOWS, which are actually the ABSENCE of light, can be made to change their locations at a rate faster than c. Just put your finger in front of a flashlight and move it across the face of the flashlight at 1 mile per hour. On a sheet of paper a few inches away from this arrangement, the shadow of your finger will "move" across the lit up part of the page at, say, 2 mph. With a bright enough light source to replace your little flashlight, by moving that piece of paper far enough away from the light source and your finger, the shadow of your finger on the paper can be made to alter its location as it "moves" across the page an any speed you choose, NOT limited by c or any other limit.

    I wonder if anyone has ever thought of doing an experiment about this because it seems that this would offer the possiblity of communicating faster than the speed of light.

    If you can move your finger's shadow across the page at a certain speed then on paper far enough away its shadow could be "moving" across a (pretty enormous) screen or paper or backdrop, many times the speed of light. Observers sent to confirm this could carry watches synchronized to the same time at a certain location on this screen or backdrop, then slowly travel apart so as to avoid any significant relativistic changes in the synchrony of their watches. Each could note when the shadow of your finger arrives and passes, then slowly travel back to their common starting point and compare notes. They would see that the time between its move past the first fellow, and the time it reached the second fellow, when divided into the distance between those 2 locations, would be faster than the speed of light.

  • speed of light is constant, its just it bounced around when going through things like water.
    Maybe if you had negative mass, you can go faster…..

  • Jack of Croydon says:

    The universe is GROWING not expanding you Sheldons have to work out what’s feeding it.
    There’s a saying “if a tree falls in a forest and no ones there to hear it does it make a noise” the answer is no. No ears no noise. Light is the same no eyes no light please take the OBSERVER out of your equations

  • If the universe is expanding faster than light away from us (which I guess assumes we are stationary or at least at a point of reference in space), would it not be fair then to say that we could also be traveling at the speed of light from the prospective of other heavenly bodies or galaxies? That we are also riding the same river of expansion? If so, why is time not standing still for us?

  • Are black holes gravity pulling in faster than the speed of light, or space collapsing faster than the speed of light?

  • A LASER beam can has a wave- particle duality, the reason it travels through space in a straight line is that in the process of lasing and transverse population inversion it acquires a greater likeness to matter. This allows the beam of light to pass through space as though it were a bullet in a straight line having a greater amount of kinetic energy than a beam of incoherent light. In other words, it acquires a greater component of matter to its wave- particle duality.

  • 8:30 I have learned that the Hubble sphere is also expanding with space therefore we could see the light of galaxys that are today outside of the Hubble sphere in the future. Did I learn wrong?

  • An analogy or thought experiment to describe motion. Imagine a golfball at rest in the Higgs field that permeates all space with Higgs bosons. This golfball is imagined to have orbiting Bosons that give it mass and an inertial resting position, held in space by the Higgs field and boson matrix. The golf club hits the golf ball, the bosons orbiting the golf ball experience the force moving their orbits outwards and imparting energy to the bosons and mass of the golf ball. The increased orbits of bosons now create greater inertial resistance to the ball from moving forward through space through the Higgs field, this brings the golf club and the ball to a near halt in space, and aligning its atoms and subatomic and boson spins. Now the increased orbits of the golf ball begin to rapidly collapse into an elongated spiraling corkscrew- like speeding up as they do so around the golf ball. This twisting wavelike cigar- shaped orbit of bosons having kinetic stored energy now begins to penetrate the Higgs field, In a similar manner that a wave of electromagnetic energy penetrates space with ease. The orbits of the bosons around the golf ball having a semi- major and a semi-minor axis in the direction of acceleration. Basically, the golf ball acquires some wavelike properties that enable it to move through space unimpeded by the Higgs field. The matter of the golf ball now has a type of flywheel of bosons corkscrewing it through the Higgs field, even though the golf ball itself is not spinning, only moving forward in space.

  • if light travels instantly to any distance from its view and dosent experience time, but the universe ages while light travels through it, why does my brain hurt so badly?

  • Time is a three- dimensional projection of an object onto a graph of imaginary numbers, therefore time is imaginary. The object in the distance is imaginary. It only becomes real when merged with real numbers in the positive x,y,z coordinates graph of reality, this requires adding energy to the object. Energy that can be present in the imaginary field and the real field, because of its wave- particle duality.

  • I have yet to hear anyone ask the right question.
    We do not even know what an electron is yet nor attractive or repulsive forces. We can only quantify and manipulate on a primitive level.
    I'd love to see what happens in 500 million years.

  • Dark matter? So suppose dark matter is in Alise's looking glass… a mirror universe. What effect does our matter have on theirs or THEIR universe.
    It's depressing to think this universe is doomed ti heat death. I'd rather have it be a closed universe cycling over and over.

  • ThoughtlessGamez says:

    Wait… I thought light didn't travel slower in transparent objects, but they didn't move in a straight line so they weren't as fast (but they were the same speed).

  • Doesn't make sense. If any point in the universe is the same as any other point then how is it possible to be moving at different speeds relative to each other?
    So if we go to one of these lightspeed galaxies, call it LG1, and look back at the Milkyway what will we see? Is the Milkyway now moving at the speed of light too or is it only LG1?

  • Since we can't go into deep space between galaxies it could just be light slows down and the universe appears to expand but isn't….

  • I came to this video due to the smart title… very smart, for it is certain.
    Once here I got the trick… on 3:25.
    Thumb up…

  • Note to self: Complain to the writers of The Simpsons that the radioactive item Homer loses down his shirt in the opening credits ,should be glowing blue.
    Accuse them of creating the worst opening credits evah!

  • István Szennai says:

    I can confirm that bs travels faster than light 🙄

    Btw. I wouldn’t put quantum entanglement on the list, as it doesn’t involve any kind of “transmission”. Brian Greene told a nice (although not exactly accurate) analogy in one of the WSF talks: you take your gloves and with your eyes closed you throw them into two separate boxes, which then you close. You don’t know which one is in which box. You take one of the boxes to New York, and leave the other one at home. When in New York you open the box, you find the left glove in it; then you will instantly know that the right glove stayed at home (and vice versa).

  • Two particles, the sum of whose speed is greater than light speed, if moving away from each other, are actually moving faster than light wrt each other

  • as far as I know the generell theoretical consensus is that we COuLD travel faster than light if we were to bend space. Which, technically, falls into category three in this video I guess

  • Shuggy McGonagall says:

    I'm not the sharpest knife in the drawer but I understood that, and its down to the Doc's way of explanation. He knows how the laymen think and explains his videos with that in mind. De Grasse Tyson, Kaku, Greene et al are all great but i am less befuddled watching Dr Don. Excellent stuff.

  • Dr. Lincoln, thank you for that explanation and for your series of videos. You have made wonderfully interesting concepts easily understood. I also liked your other video on quantum entanglement. Keep on making your videos.

  • It always amuses me to watch earth scientists say "this is the way it is" then say "we don't understand why or how" but then continue to be convinced they are right just because we can't figure it out in any terms other than those within our own limited understanding…..that is what religion is made of.

  • Closest spacecraft we can maybe make go faster than light would probably be an hall thruster engine and sling shotting it with a black hole

  • So science proves the Bible right yet again, as God stretches out the heavens. Keep denying it, though. Heaven shouldn't get overcrowded anyway.

  • So if you are traveling to another galaxie at speed of light you will never get there because of the expansion of the universe going faster than you… im right?

  • But, how do you know that the speed doesn´t cap at the speed of light? Just because it doubles the speed that we can see, doesn´n mean it automatically does that outside the observable universe? And also from what i heard, mass can´t travel FTL?

  • Kameron Briggs says:

    Can you please contemplate tachyons? I want to hear it. Im curious what areas in physics could be explained by tachyons.

    There has to be some mystery that could be explained by creating particles that are born faster than light, and never go slower than it.

  • Solomzi Nofemele says:

    Google tells me that the sun is 149,6 million km from the Earth, but since the universe is expanding, does this mean this distance is actually increasing?

  • But still, we gain "new" light from the past from stars long dead, at the present time. How can we accurately predict the engulfment of the earth by our slowly bloating star, when calculating gravitation pull, vs. expanding universe,.. coupled with all the potential cosmic events? I just don't think we can absolutely know what the future holds when. Agreed?

  • Larry The loafer says:

    Thought is fast
    Blink is fast
    Light is fast
    But the fastest is diarrhoea
    The reason is before I could think , blink or switch the light on I pooed my pants

  • You placed a example of balloon expanding the size of the dark mark Is also expanding so if we consider earth as that mark what will happen to earth? Please reply anyone

  • I call b.s. If the center of the universe is an unknown point, how can you possibly say that everything is moving away from US? To make this assertion, one would have to assume that we are at the center.

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