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# Why Can’t Anything Go Faster Than The Speed Of Light?

Einstein once called the speed of light “The Universe’s speed limit”. He claimed that traveling faster than the speed of light would violate the causality principle. For the layman, that means cause and effect. An example of this would be a bullet hitting a target before the trigger was even pulled.

Accelerating to light speed or exceeding it would also violate certain fundamental energy conditions. It could even allow for time travel.

## So why can’t anything go faster than the speed of light?

Before we can dive into that, we have to know what the speed of light actually is, what it means, and clear up some common misconceptions regarding this “universal speed limit“.

The speed of light, (or the speed of a photon) in a near-perfect vacuum is exactly 186,282 miles per second. We perceive photons (light) traveling at this speed because they are massless, or have no ‘weight’ (but they do have kinetic energy, more on that in a bit).

Every particle in our universe (including photons) move or ‘swim’ through what scientists call “the Higgs field”. As a result of this interaction, particles acquire their mass. Different particles interact with the Higgs field with different strengths, which is why some particles are heavier (have more mass) than others. Photons move through, but do not interact at all with the Higgs field.

### What does that mean?

Since photons don’t interact with the Higgs field, it means they aren’t bound by any speed limit. They’re free to move at the fastest possible speed – their own “light” speed. Why isn’t the speed of light slower or faster than 186,282 miles per second? It’s because that exact speed is a fundamental constant of our universe.

Wondering why light doesn’t travel at a different speed is like wondering why gravity isn’t reversed or what it would be like if our universe only had 2 spatial dimensions instead of 3 (4 if you include time). Those constants, along with the speed of light, were set in place when our universe was created at the moment of the big bang.

### Universal Speed Limit

Particles that have mass require energy to accelerate them. The closer to the speed of light you get a particle, the more energy is required to go faster. This is because the particles themselves get more massive in proportion to the increased velocity. In short, the faster you go, the heavier you get.

Thanks to this inconvenient truth, if you wanted to accelerate a single electron to ‘light speed’, you would need an infinite amount energy due to the electron becoming infinitely heavy. There isn’t enough energy in the entire universe to propel just a single electron to the speed of light.

### From A Photon’s Perspective

One of the methods Einstein used to help formulate his theory of special relativity was to visualize what the universe would look like from the perspective of a photon. Einstein saw that life as a photon would be quite bizarre. For instance, if you were a photon, time would have no meaning to you. Everything would appear to happen instantaneously.

Imagine for a moment that you are a happy little photon created by a star in another galaxy some 4 billion light years away. From my perspective here on Earth, it took you exactly 4 billion years to travel from that star till you reached my retina. From your perspective, one instant you were created and then the next, you are are bouncing off or being absorbed by my eyeball. You experienced no passage of time. Your birth and death happened instantaneously.

This is because time slows for you as your get closer to light speed, and at it, it completely stops. This is also another reason why nothing can go faster than light. It would be like slowing down a car to a stop, and then trying to go slower than completely stopped.

One should think of the speed of light as ‘infinite speed’. A common misconception is thinking the speed of light is just like any other finite speed. The speed of light is only finite from the perspective of the outside observer; from the perspective of a photon, it’s infinite. If you move at exactly the speed of light you could go anywhere, no matter how far, in exactly zero seconds.

### Can light be slowed down?

There is at least one real world example of superluminal (faster than light) travel. It’s cheating a bit, but it occurs when light passes through water.

Remember, nothing can go faster than 186,282 miles per second, but the photons that normally travel at that speed can be slowed down. An example of this can be seen in water where light is slowed to 3/4th of its normal speed.

In nuclear reactors, the charged particles emitted off radioactive rods through the water they are submerged in exceed this reduced speed.

Because the particles contain an electric charge, they emit energy called Cherenkov radiation. Any particles they bump into become radioactive, giving the water an eerie, mysterious blue glow.

### So what’s the speed of gravity?

It’s an interesting question that many people may not think about. Does gravity also have a speed and if so, what is it?

Gravity does in fact have a speed. The speed of gravity is technically the same as the speed of light. The reason for this speed is the same reason why light travels at the speed it does. It’s simply a fundamental property of spacetime itself. If the Sun were to disappear right this instant, the earth would continue its orbit for 8 minutes (the time it takes light to reach Earth from the Sun) before the orbit would be perturbed by the Sun’s absence.

So to sum up, nothing can travel faster than light because the speed of light can be thought of as infinite speed. To match or exceed it would be to go infinity miles per second/hour. A loop-hole does in fact exist, however. The loop-hole requires a control or warping of the fabric of spacetime itself which we’ve touched on in a previous article. (See: “Why aren’t we exploring the galaxy yet?” and “What is a warp drive?“)

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1. science4life

May 7, 2011 at 3:54 am

• CueStick

May 7, 2011 at 3:57 am

Tachyons are only theoretical particles. With that in mind, they never existed at speeds less than the speed of light, so break no rules. Their existence is somewhat reversed of light speed. They travel faster than light but they could never go slower than light speed.

May 7, 2011 at 3:58 am

Correct. If they exist, it would take an infinite amount of energy for them to go light speed or slower. They would bound by the same laws.

• raghav

January 17, 2017 at 11:49 am

What is the speed of electron in an atom and if it is approx the speed of light, then what causes the electron to move at this high speed? And how does the mass of electron not change when it is moving near the speed of light?

• Gabriel

May 7, 2017 at 11:43 am

Electrons travel at less than 1% of the speed of light, so its mass barely changes despite its speed of 2,200 km/s.

• Boson

November 27, 2011 at 2:06 pm

Tachyons are unfundemental, also meaning they do not exist… Most likely, I was just reading an artical about neutrinos being speed up to a tiny fraction faster than light! If it is true than E does not equal MC squared, atleast not in man made nature

• jb

January 21, 2012 at 9:26 pm

All transparent media have an “index of refraction”(see Source – Wikipedia.), an internal speed of light, which produces the ‘bend’ (refraction) of wave-fronts. “Cherenkov Radiation”, badly described as ‘Any particles they bump into become radioactive, giving the water an eerie glow.’ should read “light speed particles slow on interacting with the medium releasing that energy as a glow (photons)”.

TheStalkingHead: Gruff is right (see Source – Wikipedia). Contrary to common experience, speeds are not added, they are only “relative” to C (of E=mc^^2), (no matter who views it) so the “+5” just takes you a tiny percentage closer to C.

Kotsybar: (nice!: slim limerick 88669 AABBA)
A very old lady quite bright
and trav’ling at the speed of light,
said, “I am never late
but I worry my weight
goes to infinite though I’m quite slight.”

See the ‘Brain of Brian’ ‘Santa-cookie conundrum’ ;)

• phil

January 17, 2017 at 2:58 am

All this stuff is just a theory, until someone gets in a rocket and keeps accelerating nobody knows if you can travel faster than light.

• Gabriel

May 7, 2017 at 11:49 am

That’s a very ambitious, yet ignorant view. Take this case study: The Voyager Spacecraft.

The Voyager had been accelerating for an extremely long amount of time, but due to its mass and structure it was unable to surpass 62,140 km/h and stayed at this speed for a very, very long time. If your theory was true, Voyager would have reached 200,000km/h in the first year – according to my calculations.

• Abhishek

April 22, 2012 at 11:18 pm

Tachyons are hypothetical particles they don’t actually exist, there was an experiment conducted which stated that neutrinos are faster or as fast as the speed of light but that is not actually true, there was a problem with the fibre optics and the atomic clock.

• miguel miller

January 28, 2017 at 11:34 am

I don’t believe the speed of light is infinite speed, just the fastest speed of something we can detect with what science knows or our senses… If light was infinite speed it wouldn’t take any time to travel from here to other stars or from our sun to another star which takes light years. The speed of thought is a faster speed, and much closer to infinite speed. Remember Einstein’s theory is just a theory.

• Allan

June 7, 2017 at 5:53 pm

Saying it was infinite speed was in reference to no time passing for the photon. It’s still only travelling at roughly 186,000 mps.

The speed of thought most definitely has a slower speed. You’re talking bio-electics stuff now. Which is mostly electrons, they travel at 1% the speed of light. Just watch slow motion reaction video’s to people getting surprised. There’s a clear delay.

2. Andrelle

August 25, 2011 at 5:35 pm

1). In water sound waves travels faster than light waves.

2). What about blackholes, since light is unable to escape a blackhole. I’m not sure if there’s some sort of speed involved from the pull of the blackhole like you mentioned about gravity.

• Gaurav

September 20, 2016 at 10:12 am

My question is what is the relation between speed of light and time? Why does a clock become slow when we travel with speed of light? What is time, actually?

• Karim Abotaleb

November 30, 2016 at 9:06 am

When you are traveling faster than the speed of light, the clock is slowing down is because you are moving faster than light and you are time traveling. So for my opinion, Time travel is real.

3. Graham

October 22, 2011 at 11:30 pm

Wrong! Things can and have gone faster then the speed of light. There was a recent particle that went faster. I guess we can time travel now.

• Joppi

April 7, 2015 at 5:19 pm

November 4, 2011 at 1:46 pm

What if I was in a space ship moving at the speed of light, and then I ran towards the front of the ship at 5 miles an hour? Or would my blood stop moving in any direction apart from backwards (spaceship orientation)?

• Gruff

December 23, 2011 at 10:08 pm

Einstein’s theory says you cannot move at the speed of light, so let’s say your spaceship was moving at 1 mph less than c (the speed of light). Inside the ship, you observe yourself running forward at 5 mph. An observer outside the ship would see that time had slowed down greatly for everything inside the ship – for example, the watch on your wrist would be be ticking incredibly slowly. And you would be running in slow motion, maybe only doing 0.1mph relative to the spaceship. So, you speed relative to the outside observer would be 0.9 mph less than c.

• nikita sen

June 15, 2013 at 7:35 am

Yeah, I figure you are correct, but this ship moving with a speed of light can be the time machine because scientists state that if we find even a particle faster than the speed of light, time machines are possible. This means you are traveling at the speed of light but your external surroundings are in their normal state, hence people outside that ship will observe that time inside the ship is in synch with what’s outside.

• benditharder

March 30, 2013 at 1:08 am

Impossible, your spaceship would disintegrate. Nothing can push your spaceship fast enough close to the speed of light, except maybe a hyper-nova which would destroy even the atoms in your spaceship. lol

• hoosierdome

April 15, 2014 at 12:24 am

The spaceship wouldn’t disintegrate, it would become a tiny dot of light with infinite mass. It’s when you try and stop that the ship would disintegrate.
In essence you have transferred mass into energy – how does one reverse that?

• Zeeshan Asghar

May 6, 2013 at 2:44 am

You cannot move at all in your ship if its moving at light speed. Imagine you’re standing on top of a moving train. The wind is trying to push you and your train backwards and trying to slow you both down independently. Now you would find it extremely difficult to move forward because of the wind pushing you back and you would require a lot of energy. Same is the scenario with your space ship. The “HIGGS Field” is a retardation to both you and your ship independently. Your ship is somehow getting the infinite energy required to move at light speed but what about you? Your legs wont give you the infinite energy required lol!!

• TiagoTiago

June 22, 2013 at 3:57 am

Action and reaction, you would be moving faster than your ship, but your ship would be moving slower because your feet are pushing it back.

December 5, 2014 at 6:08 pm

At the speed of light, your clock would stop. You wouldn’t be able to move in your spaceship, because there wouldn’t be time to move. This is just a different way of saying what the article says. Everything would happen at the same instant.

5. Todd T

November 19, 2011 at 5:08 am

Unfortunatley, this is one area where it is not as clear cut as Einstein makes it out to be. He never actually proves the light speed constant, only declares to go faster would violate a causality principle, which in turn implies time itself also moves at the speed of light. I doubt time is constrained at all.
Now the so called proof of cesium clocks and etc moving fast around the planet in a plane or satellite only proves the mechanical or chemical mechanisms keeping time are affected by gravity and speed in different ways. A clock is not a measure of time. Not like a thermometer measures the actual thermal radiation of an object. Clocks to not measure some sort of time radiation, they are just mechanical or chemical actions that occur in predictable increments of time but are not time itself.

There is in fact no proof at all that time could be traveled, which would violate the causality principle as well, lol. Now this is not to say that we could get a particle to move at the speed of light or faster. BUT is there some unknown type of particle that could? Photons may not be the only things able to bypass the higgs field. Also, space is not constrained by speed either. Collapsing space between two points faster than light travels would be traveling between two points faster than light, relative to the observer. So traveling faster than light with currently known particles in a higgs field is likely impossible due to the energy needed for acceleration but to claim that light speed is the fastest possible speed is not proven this is assumed. Einstein was right about most everything but we must question a part of his theory where he dismisses faster than light speed over a causality principle, then turns around and predicts the nonsense about time travel, which would definitely break a causality principle.

• Arun

November 3, 2017 at 7:00 am

You said this – “There is in fact no proof at all that time could be traveled.” If it is accepted that time slows and accelerates, isn’t it as good as saying time can be traveled.

• Arun

November 3, 2017 at 8:28 am

Where does object start and where does it end? How can presume that a certain thing can’t be fractioned? The mass of an electron may be very high to be accelerated to the speed of light but how come a fraction (say, 10^-100 kg) in the mass of electron can be said to be very high?

• Barry Benedict

October 27, 2018 at 9:03 pm

This is all fun to consider but just to add to the conversation, what if the ”dark matter” we are unable to explain or see were actually some as yet undiscovered particle or energy travelling faster than the speed of light so it would be unseeable?
Would it even be considered to ”be” of this universe?
Couldn’t it also be in another ‘plane” or dimension while still having an influence on our own universe?

• Stan

December 8, 2018 at 8:30 pm

Maybe particles we can observe are not moving faster than light. But then again observing means light bouncing off those other particles and then being detected. We do “observe” particles coming into and going out of existence … which is exactly what you would expect to observe if you observe faster than light particles…

Moreover, unlike what the article claims, we do know with great certainty that gravity does move (a LOT) faster than light. The article claims that if the sun disappears we would circle around the sun for another 8 minutes (Curious when we observed that happening?). But that means we’re attracted to the point in space where the sun was 8 minutes ago. That is a long distance away from where the sun is now… If that was true we would not circle around the sun but be ejected from the solar system in a very short time (years or possibly decades, but certainly not billion of years…)

6. prashant kumar

December 10, 2011 at 6:51 am

What happens when we lessen the mass of some object? Is it possible for it to go faster than light in an area with no gravity?

7. Zulu

December 21, 2011 at 12:05 am

They found a subatomic particle that can go faster than the speed of light. So that like changes our idea of physics. makes me wonder if even bigger objects like other beings or planets can live of move faster than the speed of light.

8. Maya

January 27, 2012 at 8:13 am

So if the speed that light travels at is infinite, why can nothing go past the speed of 186,282 miles per second?

• benditharder

March 30, 2013 at 1:02 am

They just explained why up the top, read it through a few more times and you might get it. :)

9. winston anderson

February 29, 2012 at 2:28 pm

If light takes 8 minutes to get here from the sun, how can you say that is from the photon’s perspective if is created by a distant star 4 billion light years away, and then destroyed by my retina in a split second?

• kg

March 7, 2012 at 8:57 am

That’s relativity in action. The 8-minute wait you observe is from a human perspective. Likewise, if we were to patiently wait 4 billion years for that photon to reach us, it would take all 4 billion years as far as we humans were concerned. However, time does not go at the same speed for everyone. From the photon’s perspective, it is instantaneous.

• upendra

May 16, 2012 at 1:08 pm

Thank you. Now I have a much better understanding. You’re right, from the photon point of view there is no time to pass. So it feels like everything is instantaneous.

• EpiphanyUniverse

March 26, 2013 at 3:29 am

So in other words, a photon doesn’t exist until it is seen by a human eye (or human machinery)?

• TiagoTiago

June 22, 2013 at 4:00 am

No, the photon exists regardless of human eyes. From their perspective they only exist for an instant, but from an outside perspective that instant is stretched to whatever is the time it takes from it being created to being destroyed/absorbed.

• Bill

May 15, 2020 at 8:00 pm

Yikes – if you were that photon, it would seem like no time at all had passed but to an outside observer like us, it would take 8 minutes. Theory of Special Relativity.

10. Tomas Real

March 5, 2012 at 4:38 pm

It always amazes me how people complicate and fail to understand why it’s impossible to exceed the speed of light. The reason is really incredibly simple. Light is the speed of energy, so no matter how much energy you use you can’t push something faster. Going faster than light is like trying to pull your self up with your shoe laces.

• upendra

May 16, 2012 at 1:14 pm

You’re right. If it’s possible to go faster than light then light itself would have gone that speed. Light travels at the speed of light because it’s the limit.

• dsaflk

May 18, 2012 at 1:38 pm

Then how is the universe expanding faster than the speed of light?

• 6ytg

May 18, 2012 at 5:29 pm

I don’t know where you get your information but the universe is not expanding faster than light. If it were you would not be able to see or detect it. How would you be able to see it when light is what you must see it with?

• Allan

June 8, 2017 at 10:05 am

I think you’re imagining this wrong. Universe expansion is not adding another mile of space on the last mile of space. Think of it like blowing up a balloon. The universe is already infinite. The dimensions that make it up (space and time) are being stretched.

• Dark

January 28, 2013 at 3:55 pm

The thing is, light rarely travels at the speed of light if you think about it. If you measure light moving in 2 opposite vectors from our perspective they appear to have the same speed, namely, c. If you think about it from the perspective that we, ourselves, are moving, then one of those lights is moving faster than c and the other is moving slower because you must add or subtract the speed that we ourselves are moving at as the origin of the light. The only situation in which light coming from a flashlight which you hold moves at the speed of light would be if you shone it perfectly perpendicular to your line of movement through the universe.

December 5, 2014 at 6:38 pm

That isn’t how it works. ALL light rays, regardless of which way they (or you) are going are traveling at the speed of light.
If a light ray goes past and you’re watching it, and I simultaneously go by at 1/2 of the speed of light and look at the same light ray, we will both say it is traveling at the speed of light. How is that possible? Because we will disagree on how far the light ray has traveled. We will also disagree about how much time has passed. That’s how relativity works.

11. Jeff

March 12, 2012 at 3:29 am

We will not/cannot travel to other planets. The distances are so great and our limits on speed so limited that space travel is limited to our solar system. If we could ever detect a planet, the odds are that the planet would be unable to sustain life of any kind. Theories of other planets are based on what logic?? We have had radio telescopes for years and any alien life would have found us by now or we would have detected some evidence of some kind. We are alone. God has made us unique and allowed our location to be ideal!

• Huddles

November 30, 2013 at 9:54 pm

Don’t be silly. It’s only been around 75 years since the first radio signal has left Earth. That means that the only extraterrestrial creatures who could have received our radio signals have to be both advanced enough to receive them AND be within 100 light years away. So no, they probably wouldn’t have found us yet.

• CLOUD

January 27, 2014 at 4:41 pm

Not to mention signal degradation. Only a few light years away, any radio signal would be background noise at best. You’d have to aim and power specific radio waves to specific locations to have any chance at that location receiving a signal intact. Too many directions to point….

12. Ric

March 12, 2012 at 9:53 pm

In your article on the ‘Big Bang” you state that at that time all matter within traveled faster than what you say can’t happen in this article — and then slowed down. It’s a bit confusing…

• Geord13

March 12, 2012 at 10:07 pm

Matter can’t travel faster than light, but spacetime itself has no such restriction. At the moment of the big bang, spacetime expanded faster than light.

13. wayne

March 18, 2012 at 3:32 pm

So, light has no mass. Yet light exhibits a number of characteristics of having mass.
Light has momentum. Are there other examples of momentum without mass?
At what point are physicists starting to play word games? If it smells like a rose and looks like a rose?

14. Noel Brown

March 29, 2012 at 1:30 am

Well it was once fact that we would never break the speed of sound so like all other obstacles this too will be overcome someday if we don’t blow ourselves up first. How can anyone say it can’t happen? We have not mastered the universe and how it truly works yet. Perhaps folding space lol. How well do we really understand quantum physics.

15. Glenn

April 6, 2012 at 11:13 pm

I’m just a geek with a little too much time on my hands, but some things are like an aching tooth, and I have to check them every once in a while. This is one of those things.
I was told “Nothing can travel faster than the speed of light”. Okay, lets go with that. So, if nothing can travel the speed of light because the energy required to push something that fast is infinite, and because the mass of anything pushed to the speed of light becomes infinite, why can light travel the speed of light?
Light travels the speed of light because it has no mass. The same with gravity, and who knows what else?
These things have no mass because they are not influenced by the Higgs field. Okay. Why not?
Just about everything else that has mass, therefore, is influenced by the Higgs field. Why not photons, a thing, something that exists?
I don’t get it. It does not make sense.
I understand the concept of traveling at relativistic speeds. I understand that your perspective and an observers perspective are different, but to state that in the reference of light, space travel is instantaneous?
Even energy takes time to go from one point to another. As you elongate the distance, the time to travel it is longer, no matter what your speed is.
You cannot be in two places at once, no matter how fast you travel. To suppose that light exists everywhere at once makes no sense.
Why would something move if it had no mass? What would affect something that has no mass? Not even the thing that gives things mass, the proposed Higgs Boson, can give light mass, and yet light moves?

• Chuck Boyer

April 24, 2012 at 10:54 am

Thought goes faster than any matter particles. In less than a second I can place my mind/thought on any planet, any solar system.

• TiagoTiago

June 22, 2013 at 4:02 am

Zero times infinity equals zero.

• Mohammed

February 23, 2017 at 8:14 pm

Nope, zero times infinity is undefined in the set of real numbers.

December 5, 2014 at 6:50 pm

Photons have no *rest* mass. If it were possible to stop a photon, it would have no mass. But you can’t stop a photon. This is a trick of the mathematics and a wonder of nature. Moving photons have a relativistic mass and thus they carry energy at the speed of light. Light is made of photons.

The faster you move, the slower your clock ticks according to non-moving observers. A photon’s clock doesn’t tick. Time is stopped for photons. This means the instant it leaves the surface of a star is the same instant (to it) that it arrives billions of light years farther away. A photon is everywhere at the same time, from its point of view. That’s why space travel for a photon is instantaneous. It has a special property of having zero rest mass that normal matter can never achieve – so it has a special view of the universe that normal matter does not.

As to WHY a photon doesn’t interact with the Higgs field, all we can say right now is that is just how the universe works. Perhaps one day, we will know the answer.

• Dimon

March 15, 2017 at 1:33 am

Never liked answering on these kind of comments, to be honest I just spaced out for few minutes gazing nowhere, I’d recommend to start with basic physics, rather than trying to understand infinite but in infinite becomes overcomes takes adds and…..confused..

16. ray

May 14, 2012 at 6:46 pm

The reason why faster then light travel is not possable right now, and the fact that we cannot detect objects moving faster then the speed of light is…….. easy answere ALL of our technology is based at or slower then the speed of light. Its like asking a microphone to tell you threw your speekers that light exists. Yes you can pick up em fields with a mic, but it cannot tell you that its light. Furthermore even if they could make a sensor that has 0 lag time that sensor is still powered by electricity and electricty moves at the speed of light, slower if its restricted threw a poor conductor. Having said that untell we come up with somthing that either can absorb faster then light particals and conver them into electricity that we can mesure or come up with a energy sorce that isnot electric in nature and the tec that can use that energy, we will never know if objects the size of our sun or sub atomic particals are flying by faster then the speed of light.

17. Kal

May 16, 2012 at 9:00 am

Point of emission of photon is same as point of obsorbtion of atom.So it is not travelling. But we percieve time so we perceive light.

18. Bwrpurv

January 14, 2013 at 2:28 pm

You guys should all get together at a particle physics summer camp take some mescaline and discover astral travel! All will be revealed.

19. Nic

March 13, 2013 at 10:21 am

I think man is limited my his own cockiness and his ability to accept that he can be wrong. Accepting that the speed of light is as fast as you can go just because you cant imagine a way to achieve a higher speed is in itself one of the reasons that we cant. Hundreds of years ago the Earth was flat. It was a fact to millions of people, in 50 years I think the fact that nothing can travel faster then the speed of light is going to be just like the fact that the earth is flat. Just takes one person to turn fact into fiction.

20. Daryl

March 15, 2013 at 2:00 pm

Is it safe to say that there is more nothingness than “something”? Nothingness being the vacuum of space?

If so, “something” is smaller than nothing.

21. benditharder

March 30, 2013 at 12:15 am

Amazing. So you look back and see our Milkyway galaxy and there is something trying to get from one side to the other side of the galaxy. This would take billions of years to get there, even at light speed, but when it reaches the super massive black hole in the middle of the galaxy (that is pulling massive stars billions mph in orbit), the black hole will actually suck anything including light up faster than light speed.

• TiagoTiago

June 22, 2013 at 4:10 am

Actually, things being sucked by blackholes still obey the speed limit. Think of “space” as a water, and the blackhole as a whirlpool; there is a point where even the fastest boat (light) is still too slow to avoid being sucked in, but if that boat measures its speed in relation to the water like they did in the old days, by throwing a plank tied to a rope with evenly spaced knots onto the water, they would still count the same number of knots.

• Hazardous

January 20, 2015 at 6:40 am

I find it easier to understand speed of light from spacetime perspective. Instead of thinking of a photon crossing the fabric of spacetime, imagine the fabric itself shrinking towards it. For a photon, the fabric rushes up at infinite speed thereby stopping the time…

A photon doesn’t travel straight, it is rather guided (and I am taking a few liberties with that word) by the curvature in the fabric of spacetime. So when a photon crosses near a huge body (our Sun, for example) which curves spacetime, the photon curves on it too, aka gravitational lensing. This was the proof (observed during a total solar eclipse) which vindicated Einstein’s theory for the first time.

If you are still with me, it should now be easy to see why black holes can eat light. They curve spacetime fabric to the point of drilling a hole (the pun is very intended) in it thereby swallowing anything which travels through that fabric.

22. Tanmoy

April 6, 2013 at 2:17 am

If light has no mass, why does it get pulled into black holes?

• Jay

June 6, 2013 at 4:36 am

The gravity of black holes create infinite or near infinite curvature in the space within the event horizon. Anything caught in such a region of space would never be able to get out of it. To an outside observer the photon would be going round and round the curved space, not due to gravity

• TiagoTiago

June 22, 2013 at 4:12 am

Photons moves in a straight line, but black holes curve space itself. From the point of view of the photon, it looks like a straight line is actually a spiral towards the black hole.

December 5, 2014 at 6:59 pm

Two ways of looking at this. 1) Moving light has energy, which is equivalent to mass. 2) Gravity is a warpage of spacetime. When light travels into a black hole, it is simply following a straight path through a warped space time. These two views are equivalent.

23. bukweat

May 5, 2013 at 4:20 pm

Theoretically, with the proper (MM) mechanical machine (assuming one could construct such a machine- almost certainly impossible) the communication of information could be made to move/travel almost instantaneously. MM could hypothetically be constructed by utilizing an unbreakable, probably straight, and absolutely rigid string/wire/cable transmission line (obviously made of some currently unknown material and/or process). Assume a tangible cable/line lain down from one end of the universe to the other (or for that matter almost any line distance). Functionally made of any device capable of vibrating/moving the full cable back and forth (just for amusement let’s say a cesium atom powered device can do it) the MM could communicate information relative to any distance via the established cable and code. Transmitting information instantaneously to other points would only be limited to MM’s location, length of the wire/cable, the communicating language/code developed and the transmitter and the receiver. MM communication would occur much (infinitely) faster than communication by current devices which utilize the speed of light. Theoretically we have almost instantaneous communication from one edge of the universe to the other.
Laying the communication line(s) would be a centuries-long slow process but once established the information communicated along the line could travel almost instantaneously.

• Jay

June 6, 2013 at 4:41 am

Not really, since any information generated by motion triggered at the source would only propagate along the medium at a max of c. If you laid such a cable between Earth and the sun, any vibration you initiate here will only be received at the other end after eight minutes.

• Gary

October 22, 2014 at 5:04 am

What if it was so dense it could not be compressed anymore? What would happen and how would the energy be transferred if it could not push the atoms any closer?

• Marshal

December 10, 2014 at 4:57 pm

Then that matter would be infinitely dense, and turn into a black hole.

• Bill

May 15, 2020 at 7:57 pm

Nope, sorry. Black holes are not infinitely dense, only so dense that their gravitational pull prevents light from escaping. The only “infinitely” dense state existed immediately before the Big Bang.

24. patrick

June 7, 2013 at 1:36 pm

Mass is not “heavier”, it has more matter – not more force of gravity upon it.

25. patrick

June 7, 2013 at 1:42 pm

I don’t agree. A photons “life” is instantaneous. Still travels at the speed of light – a finite speed! It still takes time to travel a set distance.

26. john

June 27, 2013 at 2:23 pm

Just to throw it out there, this article is outdated. With the fact that a couple of particle DID, in fact, go faster then light (in a partial accelerator), and the discovery of the Higgs Boson particle (AKA the God Particle), faster then light (FTL) travel is possible. NASA is so convinced that this is possible that they have formed a team to start working on said drive. It’s kinda a warp drive, but not completely. There has been a lot of discoveries in the last few years that have been proving Einstein wrong! It makes one wonder about what else we were wrong about now…

• Allan

June 8, 2017 at 10:13 am

Incorrect. Einstein’s theory of relativity has been proven correct time and time again.

27. Ted

July 1, 2013 at 7:56 pm

If you could get a bus going the speed of light and you walk from the back of the bus to the front of the bus wouldn’t you be going the tiniest bit faster?

28. Dion

July 12, 2013 at 3:05 pm

Let’s say light is emitted in front of a black hole that was just created at the same time the light was emitted. Since gravity is the same as the speed a light, wouldn’t that light would always be in front of that black hole and therefore if the two move at the same “speed” they wouldn’t catch each other.. Is that right? (based on the “What about the speed of gravity” section.)

July 20, 2013 at 11:02 pm

Which of the following is true:
a) Nothing can accelerate beyond the speed of light
or
b) Nothing can travel faster than the speed of light
Your’s Sincerely,
Dazed & Confused

• Allan

June 8, 2017 at 10:14 am

It’s “Nothing with mass can accelerate to the speed of light.”

30. William

August 4, 2013 at 10:29 pm

Our instantaneous observation of the universe in which we live is the energy that drives ones reality, so this to me would seem to serve as an example of something which is “faster then the speed of light.”

31. changocoy

August 15, 2013 at 12:49 pm

I think the part about gravity acting at the speed of light might be wrong. I am no expert, but i seem to recall Steven Hawking commenting on how gravity baffles science by acting instantly on an object. So if the sun “disappeared”, the orbit of the earth would instantly go off course. Could be wrong though…

32. Glenn

August 17, 2013 at 2:07 pm

Recently, scientists have said that they have clocked the speed of “the seemingly instantaneous interaction between entangled quantum particles” (bypassing the concept of measuring something faster than we can measure) http://www.extremetech.com/extreme/150207-chinese-physicists-measure-speed-of-einsteins-spooky-action-at-a-distance-at-least-10000-times-faster-than-light
Riddle me this joker…if nothing can travel the speed of light or faster (except light of course because it’s “special”), how can quantum particles interact instantaneously?
Energy wave…physical connection…what? And if this is correct, does it not invalidate the proposition that the speed limit of the universe(s) is the speed of light?
Put directly, this cannot happen, because they cannot communicate, in any matter whatsoever, equal to, or faster than, the speed of light (based on the prevailing theory).
So who’s wrong?
Maybe it’s magic? And, for the love of science, please, no one mention Schrodinger’s cat.

• Kushina

August 17, 2013 at 2:14 pm

Riddle me this joker…if nothing can travel the speed of light or faster (except light of course because it’s “special”), how can quantum particles interact instantaneously?

Quantum entanglement is not information traveling faster than light. It’s something entirely different. It appears “Spooky” because it seems like it is, but in reality, it’s not. That’s why Einstein called it spooky action at a distance. It’s a trick, an illusion.

December 5, 2014 at 7:02 pm

Entangled particles simply *know* the state of their entangled partners. This isn’t recent. The EPR paradox has been known about since 1935. It has been demonstrated to be true many times since 1976.

33. Marci

October 31, 2013 at 2:07 pm

I strongly disagree with anything that says nothing can go faster then the speed of light. At one time they said you couldn’t go faster then 30mph then it went to 100mph then they said nothing can go faster then the speed of sound (tell Chuck Yeager that). The only reason people say nothing can go faster is because no-one has done it yet. The person talking about being in a ship moving at the speed of light and running forward at 5 mph, yes you are right. You would be moving at the speed of light (186,282 miles per second) + (5mph) but it would be faster the the speed of light.

Secondly, moving past the speed of light would not make you time travel. It would only get you from point A to point B that much faster. And seeing as light comes from every direction as you hit the speed of light, you would see nothing change to the normal person traveling at the speed — only the instruments could detect the photon particles that were traveling the same direction as you would seem to stop as you matched their speed then reverse as you past the speed they are traveling at. Think of it as 2 cars traveling at night in the same direction and all you can see is the cars — 1 doing 50mph the other 40mph. The 1 doing 50 is moving away from the slower but if the slower was to pick up speed to 60mph then the car at 50mph and ahead would seem to be slowing down as now the other cars is catching up and as the cars past each other. They both would seem to have stopped for a split second. The one that was ahead would seem to be going backward but it really isn’t.

Speed is a concept of man and there is No limit. The faster you move, the less time it takes to get from point A to point B — that’s all speed is. The only thing about time, is that its infinitely divisible (a day divided into hours, hours divided into minutes, minutes divided into seconds and so on) so no matter how fast you go you will never time travel. Like I said, you only get from point A to point B in a shorter amount of time. Another thing is if 2 friends traveled from point A to point B, it took one friend 1 minute to get from point A to point B traveling at 186,282 miles per second and the second friend traveled from the same point A to point B only doing half the speed. The first person and the second person would still be the same age when the second person reached point B. The only thing that would happen is that the first person would have to wait the extra time at point B for his friend to show. Still no time traveling or miraculously becoming younger.

The reason why no-one believes faster then light travel is possible is because everyone has been brainwash to believe that. Like everyone use to believed the earth was the center of the universe and was flat because they were told that by others till some started to think on their own.

34. Greg

December 11, 2013 at 4:30 pm

I’m having a bit of a discussion with a friend who believes that one day mankind will develop a way to travel at or faster than the speed of light (he watches Star Trek… go figure). I explained why it’s not possible, and he agreed with that, but reminds me that they used to think it wasn’t possible for man to fly either. So for arguments sake, lets say we did discover a way. I know there is a lot of matter in space, what would happen to a spaceship about the size of the space shuttle, traveling at the speed of light and it hit something as small as a water molecule, or even a hydrogen particle? Nothing, minor damage, or total destruction… Nothing left but dust (that’s my guess).

35. David

January 5, 2014 at 9:09 pm

I think it’s important that we stop thinking about going beyond the speed of light. The only reason I say this is that speed is a function of distance over time. And as we have established the “speed of light” is effectively the limit of observable velocity, a better way of putting it would be to say the limit of observable interaction. The speed of light is infinite, which means anything on this energy level effectively becomes observable at any point in space time. We give it its speed because of the point at which we observe the interaction, however, this is from the observers perspective and so is limited by our perception of space time. The only way to alter this limit would be to manipulate the higgs field. For example, it’s kind of like having a large pipe which gets thinner and thinner, the velocity of the water in the thin part is greater that that in the thicker part to allow the flow to stay constant. If you could manipulate the Higgs field then you could theoretically change the observable interaction and there for be able to move beyond the normal limit.

36. John

March 14, 2014 at 1:25 am

Did the big bang travel at the speed of light? Or did it travel faster than the speed of light and now we are left with the 186k+ miles/per sec. expansion? My opinion, SOL is slowing down. Re: dissipation theory (my own). Based on initial energy with finite resource = SOL eventually slows down itself to 0 = time itself (or the expansion of the universe) eventually stop. Without expansion speed, the universe must retract because of the created gravity force from the expansion of the universe will pull back and then will implode. The process starts again and again and again, to infinity repetition. Energy or motion/movement is essential for existence of matter. Movement of objects/particle matter is measurable for speed. However, without particle mass there is no measurement of light speed only space that will eventually stop expanding then draw back. The retraction or implosion will be at the same rate of “speed” as the big bang. Most likely faster then the SOL.

37. Mark Cloutier

May 4, 2014 at 9:44 am

After years of observing the effects of radiowaves and electrical signals interact in radio semiconductors it seems to me that nothing can move without interacting with the ether. I don’t believe free space exits. Missing matter, Higgs field, or what ever you want to call it. When a transient current flows an energy is stored in the matter. The faster it goes the more energy is stored. This is real energy being left behind. Hence an infinite velocity is not possible. The transient runs out of energy. Particles loose energy when they travel through the ether and make waves in the ether. Waves in the ether propagate with real energy and make your phone work.
Electrons move when pushed around by waves in the ether. There is no free lunch. No free space.

38. Keith

June 18, 2014 at 7:49 pm

You CAN travel faster than the speed of light and still protect causality, Einstein was wrong. This is what I predict will happen in the next 20 years:

1. We will discover that light is in fact nothing more complex than a wave of energy moving through gravity. Our eyes have simply evolved to detect waves of energy in gravity in exactly the same way as our ears have evolved to detect waves of energy in a gas.

2. Gravity, including acceleration and constant acceleration (centripetal force) when applied to matter, causes the movement of particles to slow at the quantum level. This is why time slows down when matter is accelerated or placed in a high gravitational field. Time is actually only a measurement of the relative movement of matter and if all the subatomic particles in any piece of matter slow in their movement, time itself is slowed.

In this theory, we don’t need to worry about the countless paradoxes of Einstein’s work. Even at maximum acceleration, time could only ever be effectively stopped because the force g would be so strong as to stop the movement of all the particles in the matter. The movement of the particles could never be reversed, which is the only way time could be reversed, so at any speed causality is protected without the need for a universal speed limit.

I know I’ll be called a crackpot, but so was Darwin. I’ve been working on this theory on and off for 10 years and resolves every single paradox which Einstein’s work raises, such as the famous Twins paradox, the concentric circle paradox and the paradox of a muon particle travelling at close to light speed in a particle accelerator. You heard it here first. :)

39. Bhagwan K

October 10, 2014 at 3:20 pm

The article does not make sense. It’s like first assuming that Mr. A cannot be wrong and then proving that something Mr. A said is right. There is no test so far that proves the speed of gravity is equal to speed of light. So far gravity has either shown that it is instantaneous or the laws of motion does not hold. Also, gravity distorts light (black holes) so there is energy in the universe that allows photons to travel at the speed of light.

• Marcus Weng

October 11, 2014 at 2:21 am

So far gravity has either shown that it is instantaneous or the laws of motion does not hold.

Gravity is instantaneous. Everything is relative, this is what people get hung up on. The speed of light, for all intents and purposes, is instant. We can assign a speed to this because of our frame of reference (relativity). From a photon’s perspective (and from gravity’s perspective), it’s instant.

40. ZZBrandon

October 27, 2014 at 2:48 pm

What about gravity? If gravity affects the speed of light and travels at the speed of light, how is light able to travel at all? Also black holes which are dense masses of gravity are so strong that light cannot escape. Based on that, wouldn’t the speed of light in a vacuum be an average based on the equilibrium of gravity’s pull on light from varying directions throughout the universe? Are we not assuming that light’s speed is constant and is the speed of energy? We have actually observed the sun gravity pulling back on light that is trying to leave it so how can we not take gravity into the equation when light is moving through space? Obviously it is affected by something or we wouldn’t have observed it.

41. Bigpicture

November 29, 2014 at 8:10 pm

I never have been comfortable with the speed of light being a constant theory. I am not of mathematical bent, but of “a theory needs to stand the test of reason”. It all started with the is there an “ether” or “no ether” debate, and irrespective what they choose to call it, it is about is space empty or not? Then along came the Michelson–Morley experiment, which just basically measured “if the earths rotation had any effect in the measured speed of light” which apparently it doesn’t. But it is a big twisted leap in logic from the results of this experiment being interpreted that (1) the speed of light is a constant (2) there is no “ether” in empty space. But there is “dark matter” and “dark energy”, Oh if we call it a different name, maybe it will go away.

Einstein never claimed that there was no “ether” he just maintained that it’s existence (or not) did not matter to the Relativity Theory. And of course the whole foundation of these Theories is that the “speed of light is a constant”. BUT WHAT IF IT IS NOT? What is there really is some sort of foundational media through which light propagates? What if this foundational media affected both the physical dimensions and time measurements of any planetary bodies moving through it? Then the M&M experiment would be pure crap, and prove that this was only a local phenomena. I never could understand the logic of how gravity could affect the “direction” of a light beam, but not its “speed”, it just never made sense.

42. Noob

December 16, 2014 at 3:22 am

If time is basically nothing for photon, and if earth would be destroyed in many more years to come, have photons already seen the Earth being destroyed?

43. duke

December 16, 2014 at 5:35 pm

So according to the photon, it doesn’t travel and everything is instant, but according to an outside observer, it can take billions of years for the photon to travel to the eye. So what is the reality? Has it traveled instantly or not? Who is being tricked? Is the photon traveling through space at 186,282 mp/s and it doesn’t know it? Or does it just appear everywhere in the universe in an instant but we think it has taken a billion years to reach us?

If a star dies right now and it is 4 billion light years away, it will still shine in our sky for 4 billion years, even though the last photon would have left 4 billion years ago.

44. utkarsh kumar singh

January 30, 2015 at 8:53 am

The article says that if “you move at exactly the speed of light you could go anywhere, no matter how far, in exactly zero seconds.“. But wouldn’t that make the speed of light to be infinite m/sec and not 300 million m/sec?

• Frankie Man

February 3, 2015 at 9:16 am

That’s why it’s called “relativity”. Everything is relative. It means spacetime for you may be very different for me.

For a photon, yes, it’s “infinite speed”. But for us, our frame of reference is different. We can measure light’s speed. If you’re a photon and you tried to measure your speed, it would be infinite. But to outside observers, it’s not.

That’s why it’s called relativity and not “Absolute”. If spacetime was absolute, then yes, it would have to be the same in all reference frames. But it’s not. Photons as one commenter here has noted, really live in a different reality from us.

45. Satyam

February 1, 2015 at 12:10 pm

Can someone please explain to me why a photon doesn’t experience time when traveling at speed of light?

• Samual A Wise

February 3, 2015 at 9:08 am

A photon has no mass. Since it has no mass, it’s not bound by any restrictions. It doesn’t move through “spacetime” as we know it. The Higgs Boson can’t reach out and grab it.

Since it isn’t bound by any speed limit, it moves, from its perspective, at infinite speed. It literally teleports from point A, to point B. It doesn’t experience any passage of time. Remember, time is relative according to Einstein. We experience time thanks to relativity but photons do not since their relative frame of reference is different from ours. They almost exist in a separate reality from us.

May 12, 2015 at 9:26 pm

There was a suggestion apparently given by Einstein but got forgotten and not seen mentioned anywhere now. It goes like this (my understanding); there is only one speed in nature and that is the speed of light (the numerical value of it comes from the our arbitrary choice of the units of length and time. It changes by changing these units and normally taken to be c=1 in a lot of research). The reason why we see other speeds is because singlets moving at c trap each other, make a doublet and have a velocity zero as a result and this is the smallest element of mass. This way singlets are energy and doublets are mass. This will also correspond to bosons (singlets) that can be aggregated at will and fermions (doublets) that occupy a certain space that cannot be occupied by others.

If you break a doublet you get two things (photons) flying in opposite directions at c. The mass and energy become one by this construct and E=mc^2 is automatically satisfied. Now if you add more ‘things’ moving at c to a doublet at zero velocity, the speed(momentum) will increase a little and if you add another you can increase it further and so on, but the maximum speed you can reach is c which you can easily check using simple momentum relations (take the mass=1 for each particle). Further more, the energy increases indefinitely with such addition so is the momentum- despite the fact that the speed can not be faster than c. This explains the apparent increase of mass with the increase of speed. Also explains the fact that you can create heavier particles by colliding fast (but light) electrons. Fast electrons for example, are basic electrons with bits stuck to it that were originally moving at c. When you accelerate an electron, it radiates by shedding these extra added bits. An electron and a positron annihilate by destroying the doublets in each and releasing the constituents that fly at c.

47. Gary Mark Skinner

June 12, 2015 at 5:04 am

Does this mean that every photon has been (or could be) at every point in the Universe at once?

48. snaktack

September 2, 2015 at 8:29 am

Wouldn’t a particle accelerated to the speed of light have its mass increased to infinity? Wouldn’t this create a singularity with infinite mass and gravity?

November 6, 2015 at 8:26 pm

I’m sorry, but you’re you’re the one who is wrong. While mass doesn’t increase directly, it does so indirectly through the mass energy equivalence. It “functionally” has the same effect which means the distinction you’re making is but a moot point. You’re being pedantic and normally that would mean something, especially in science, but in this case, it means nothing since the object does in fact, get heavier. As the math shows, once you reach the speed of light, the energy/mass increases to infinity, creating a black hole or a singularity. The end result is the same.

• Jamie Anderson

November 12, 2015 at 11:32 pm

Mass is not a form of energy – you’re the one who’s confused. If mass were equivalent to energy there wouldn’t be two words for the same thing and there would be no equations like E=mc2. Capiche? There is no such thing as energy/mass, or mass increasing indirectly, or functionally. Physics requires precision of language.

November 14, 2015 at 10:48 am

You typed it out yourself E=mc2. “Energy = Mass” Mass and energy are the same thing, they’re just in different forms. It’s the same way an ice cube and water are the same thing, just in different forms. They’re both still water. Even then, the point you’re making is irrelevant in this context; even if it was different, it still “functionally” has the same end result/effect. In fact, if you were to plug in E or M into the equations for light speed, the solution is still infinity. It doesn’t matter because you get the same answer. A singularity.

This is an article for the layman, it’s not some dissertation or mathematical proof where “the precision of language” has any relevance. Its goal is to convey complex ideas in a way that the average person, someone without a background in physics can understand. As such, pedantry is actually harmful.

• Jamie Anderson

November 16, 2015 at 8:19 pm

All the article had to say was “As a mass approaches light speed it needs disproportionately more energy to go faster. It can never reach the speed of light as that would require an infinite amount of energy.”

Saying that mass increases as speed increases is confusing, anti-intuitive, and just plain wrong. What happens if they read this article then pick up a high school science book only to learn that mass does not increase as an object approaches light speed?

• karamat

August 13, 2017 at 11:34 am

what about a spaceship revolving around the earth, powered by the solar energy and accelerating at 10m/s ( a man on a spaceship will feel like home as the gravitational pull is 9.8 m/s). It will achieve 315000 km/S in a year time. The increase mass principal may apply only if we tries to achieve the speed of light instantly (due to inertia). It appears nothing will happen even if we go twice the speed of light. once the ship stop accelerating, the man on the ship will feel stationary and weightless but to us will see moving with the speed of light (if we could see). it will be just fast moving object completing 7 circle around the earth in one second or 14 circle in one second. Where is the time dilation fantasy in this? I am no physicist, excuse me if I am wrong

50. steveweinberg

January 14, 2016 at 10:27 am

How does a photon have the energy required to move at the speed of
light …… forever? At least for billions of years?

51. EndertheDark TDMFan

January 14, 2016 at 6:20 pm

Empty space can travel faster than the speed of light. All we have to do is harness the power of empty space, and boom, faster than the speed of light.

52. hencca

July 28, 2016 at 2:09 am

I’m trying to understand. Let’s say I’m a photon, starting my journey one light year away from earth. I travel instantaneously to earth, yet I see it spinning 365 times before I reach it. How can it be both?

• RA

August 15, 2016 at 4:54 pm

Hmm. I don’t think you will be able to see it spinning because it is instantaneous, there’s no change… time stopped.

• Tiyamike Thakwalakwa

September 1, 2016 at 9:03 am

I have been following on different forums the discussions on the Speed of light. I have always wanted to put forward the correct conclusions drawn from Theory of Relativity.
-Nothing with mass can reach the speed of light.
The equations of relativity drawn by Albert were derived by considering clocks placed in two frames of reference relative to the observer of those clocks. Example is to put one clock on earth and another on a particle accelerating somewhere in Space. To tell the time on the particle an observer on earth needs to visually receive the light reflected by the clock. Notice that light is being used to transmit the clock signals between earth and the particle. The photon reflected from the clock on the particle has a finite time to reach earth and register a clock hand tick to the earth observer. So the event of one clock tick on the particle cannot be said to happen simultaneously by observer on earth and observer on the particle.
Let the particle accelerate away from earth.
• Observer on earth will be receiving the information about the particles clock tick evermore slowly leading to conclude that time is ticking more slowly on the particle compared to his own clock.
• Observer on the particle observing the particle sees no change in the periodic ticks of his clocks but if he sees the clock on earth he will conclude that time is passing more slowly on the earth clock.
Notice that these effect are Relative (Relativity) not actual as they depend on the finite propagation times of speed of light whose speed is agreeably constant in all flames of reference.
Here is where interpretation of the Special Theory of relativity is messed up by a lot of people.
-Nothing with mass can reach the speed of light.
This is a wrong conclusion because it is now applied to everything without consideration of the relativity. If the observer and the observed are in the same frame of reference, the speed at which the particle can travel at has no limit as there is no relativity applied.
However if the observer and observed are in different frames of reference, the observer observing the motion in the other frame of reference has an upper limit as to what he can meaningfully observer in the other flame of reference. This limit is determined by the speed of light bringing information to his eye.
A correct conclusion is – No information about speed, mass, length and time can be transmitted to a stationary observer in relation to an accelerating frame of reference as the speed of the accelerating system approaches the speed of light.

September 2, 2016 at 6:55 pm

As a child I often answered a why-question with the word “because”. It’s just an obnoxious way of saying that you don’t really have a good answer, but at least it doesn’t take minutes away from the person who asked the question like this article did.

I used to love physics up until high-school and the reason was that everything they taught was logical and based on something more fundamental that could also be explained. At university level all this fell apart. Now I have come to believe that physics works this way.
Someone comes up with a formula that matches observed experimental data. All good so far, but the next step is to try to explain why the formula looks the way it does and that is where it falls apart, because there is no more fundamental knowledge to base these assumptions on. They become pure fiction.
What is really humorous is when a group of scientists comes up with an alternative set of formulas also matching known data(like string theory) also comes up with an alternative set of made-up assumptions that collide with the first groups assumptions and physics boil down to who you think is the best science fiction writer.

• Frank Reynolds

September 12, 2016 at 2:00 am

You’re missing a fundamental point of the article. The answer is laid out plainly, it gives you the “why”. It’s just not an easy answer to comprehend or wrap your mind around.

The speed of light isn’t the speed of light, it’s “infinite speed”. We only call infinite speed “the speed of light” because of relativity. It’s something we can relate too, and understand. Space, time and speed are all things that are relative. There is no single “correct” answer. For something going the speed of light, traveling from point A to point B is instantaneous. Whether you’re traveling 1 mile or 1 trillion miles — it is instant, like teleportation. But from our perspective, it’s not instant. This is the part that people are having trouble wrapping their minds around. We can measure that speed since we aren’t moving at the speed of light. Someone moving at the speed of light would be unable to measure their speed because everything happens instantly. No passage of time to measure.

You yourself are suffering from a collision of sorts — a collision of how you perceive the world to be and this explanation of the speed of light which contradicts what you know to be true. Your mind can’t make sense of it so it immediately rejects it. This doesn’t mean you’re dumb, stupid or ignorant, because this happens to the smartest and brightest, but it does mean you have a closed mind. One which isn’t as accepting of adopting new information. It means you have trouble adapting and evolving with changes.

54. Zoe

September 6, 2016 at 4:59 pm

How are light rays affected by gravity if the photons that make it don’t have a mass?

• Allan

June 8, 2017 at 10:22 am

Because gravity isn’t a force that attracts matter. Gravity is the curve in space itself, photons are simply gliding across the lines of the universe. If they hit a black hole it would be like getting grabbed by a whirlpool.

55. Tim

October 31, 2016 at 1:02 pm

Light is affected by gravity because gravity bends spacetime. Light travels through spacetime and now it’s plane on witch it travels has been bent around the mass that is creating the gravitational field that is bending spacetime. Although spacetime is 4 dimentional, to make it easier to picture, you can think of it in 3 dimetional terms by stretching a piece of rubber. This rubber will represent spacetime. Then place a mass in the center of it. The rubber will now bend around the mass. If light were a ball rolling past this mass, it’s path would be changed as it rolls past it. However, unlike a literal ball, light always moves at a constant speed so it’s speed would be unaffected by passing by the mass.

56. P.Balagurunathan

March 9, 2017 at 12:37 pm

The LIGO experiment detecting the gravitational waves by Sep 14,2015, emitted during the merger of two black holes at last confirmed the speed of gravitational waves is really more than that of light! Any doubts on this?

• Allan

June 8, 2017 at 10:29 am

You’ll need to site your source that states this. I believe it is incorrect. I haven’t heard of anyone making this claim.

From the LIGO webpage:

“Einstein’s mathematics showed that massive accelerating objects (such as neutron stars or black holes orbiting each other) would disrupt space-time in such a way that ‘waves’ of distorted space would radiate from the source (like the movement of waves away from a stone thrown into a pond). Furthermore, these ripples would travel at the speed of light through the Universe, carrying with them information about their cataclysmic origins, as well as invaluable clues to the nature of gravity itself.”

https://www.ligo.caltech.edu/page/what-are-gw

March 10, 2017 at 11:04 am

March 10, 2017 at 11:06 am

Also why are photons slowed down if they don’t react with higgs field at all?

59. Kirby

September 19, 2017 at 3:27 pm

Firstly, the section labeled “So why can’t anything go faster than the speed of light?” does nothing to actually answer that question.
The next section: “What does that mean?” refers to us living in “spatial” dimensions: “3 (4 if you include time)” Time is, by definition, NOT a spacial dimension. That is why people refer to “time AND space”
“Universal Speed Limit” – Never explains WHY the particle gets heavier
In the section “From A Photon’s Perspective”:
the article states that “One of the methods Einstein used to help formulate his theory of special relativity” I believe his theory was on spacial or spatial [depending how you prefer to spell it] relativity. This section also states that “If you move at exactly the speed of light you could go anywhere, no matter how far, in exactly zero seconds.” That defeats the EXACT purpose of defining a speed. That statement basically negates the fact that light does, in fact, have a speed.
“Can light be slowed down?”:
“Any particles they bump into become radioactive, giving the water an eerie, mysterious blue glow.” Wouldn’t that make all water radioactive? And we were so fearful of radioactivity! Haha!
“So what’s the speed of gravity?”:
“The speed of gravity is technically the same as the speed of light.” That is just not true. The speed of gravity is approximately 9.8 meters/second^2, and as stated previously in the article, the speed of light is 186,282 miles per second

• The Correct One

November 21, 2017 at 3:02 am

“What does that mean?” refers to us living in “spatial” dimensions: “3 (4 if you include time)” Time is, by definition, NOT a spacial dimension. That is why people refer to “time AND space”

They did say 3, they said 4 in parenthesis for the pedantic buffoons like yourself.

“Never explains WHY the particle gets heavier”

It doesn’t get heavier in that sense, it gets more massive.

“That defeats the EXACT purpose of defining a speed.”

You missed the point of relativity. Relativity states everything is relative, which means you need a speed to measure against. Otherwise how can something be “relative” to something else? It’s a moot point anyways because at the speed of light, everything happens instantly. There is no passage of time.

“That is just not true. The speed of gravity is approximately 9.8 meters/second^2, and as stated previously in the article, the speed of light is 186,282 miles per second”

You’re not particularly intelligent, are you? That 9.8 meters per second squared is the Earth’s surface gravitational acceleration. That’s how fast you fall towards the earth, in a free fall. That is not how fast gravity propagates.

60. izraul

November 13, 2017 at 1:56 pm

I cringe every time I hear the “big bang” theory. An explosion cannot and does not last 13 billion years, no matter how big it is. The universe isn’t speeding up because it’s being pushed by an ancient explosion, it’s speeding up because were getting closer to a blackhole. It’s more logical to think we live inside of a giant black hole with billions of other black holes inside of it that are around us tugging from all directions.

The “Big Bang” could very well have been a “Big Suck” instead. Being sucked could also seem like being pushed. But since it’s nonsense to think an explosion would not only last for billion of years, but strengthen in force after 13 billion, it’s more logically sound to assume these forces come from a black hole or holes. Anyway, that’s my opinion. I can’t explain why or how I know, but I know I’m right. I’ve always known. It’s the only thing in my life I’ve ever been sure about since I was kid. Maybe not all of it, but we do live inside a black hole. That much I’m certain of.

• BWis

June 16, 2020 at 5:29 am

I don’t know if you’ll ever see this but you’re totally misunderstanding the Big Bang. The Big Bang is not an “explosion” from a point in three dimensional space. Think of the surface of a balloon, and suppose the universe was 2D. As the balloon inflates the surface area expands. Each point on the balloon appears to be moving further apart faster and faster, but it’s really the surface of the balloon expanding.

Now think of the universe as if it was a part of the flat surface of the balloon, but it’s actually three dimensional from our perspective. There IS NO CENTER of the explosion from our perspective. Everything is stretching in all three dimensions. There is no center of the explosion in our three dimensions.

61. izraul

November 13, 2017 at 2:03 pm

And it just so happens to be that a black hole is the 1 thing light can’t escape. I’m not a scientist or a physicist or even a lab technician. I’m just an average nobody who didn’t graduate high school, and yet for some unknown reason, I just know I’m right. None of it makes any sense to me, except the black hole. Go figure.

• Ecneics

February 5, 2018 at 7:37 pm

Izraul, I like the way you think. I have the same arguments as you do. Physicists can site so-called facts without answering the questions you pose. My biggest argument is how the speed of light is finite and takes time to travel, yet it has been said that travel would be instant for the person traveling at that speed. Also, they speak of time slowing down or speeding up based on the speed of travel. This is being based on clocks? Mechanical devices made by man? Change the surroundings/pressure/gravitational forces of any object (especially a clock and it’s mechanical workings) and it’s going to have an effect on the object. I think that argument needs better testing tools than a clock. As far as your theory of us being inside the black hole, I like it. Perhaps the center of our galaxy is actually the exit of the hole we are in. It also supports the multiverse theory. Go through the hole and you’re in another universe. It has been said that there are numerous black holes in our galaxy but the super massive center of our galaxy is 28,000 light-years away. Why aren’t Astro-physicists sending probes to closer black holes since they claim the holes are everywhere and of numerous sizes and places.

62. Virtualabe

December 13, 2019 at 4:26 am

The speed of light is a Universal constant? Where does that come from? I was asking why the speed of light has settled on being 186,000 miles a second, opposed to something else? It’s not an answer. I hope someone knows and would explain it in layman terms. Thanks!

• Ted Fundy

March 23, 2020 at 3:27 pm

A layman way of saying it, IS “that’s just what it is”. Let me ask you a question, why is up, “up” and down left, down or right? Why does gravity pull us down to the ground instead of pulling us straight up?

If you were going the speed of light, you have attained infinite speed. You can’t go faster than infinity. And by infinite speed, I mean instant speed. You could travel from the other side of the universe to Earth in literally the blink of an eye. How can you go faster than instantly? It’s like bringing your car to a complete stop at a red light, then trying to go even slower than completely stopped. You can’t go slower than not moving at all.

63. KJK

January 23, 2020 at 2:32 am

Let me get this thing straight. How can photons have kinetic energies if they don’t have mass? Well an elementary physics says you must have mass of an object and its velocity( or speed , however you like it ) because the kinetic energy is: (mv²)/2.
Are you saying this equation is not working any more ?
Or what the heck happened to physics ?

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