I heard that it is theoretically impossible to reach the speed of light? Is that true?

Answer 1

Yes - at least according to the special theory of relativity.

Answer 2

Yes. As you accelerate toward the speed of light, several things will occur. First, no matter how fast you are going, light will still pass you (even from a source behind you) at exactly the speed of light. So you cannot catch up to it. In addition, your mass will increase such that it becomes more and more difficult to accelerate further. The speed of light is a limit that cannot be reached using technical knowledge that we have today.

This has been demonstrated repeatedly in particle accelerators, so it's not as theoretical as it may sound.

Answer 3

Yes. The mass of an object is relative to its velocity in any given frame of reference (that is, imagine a ball being thrown from a moving car at a person: say the ball is thrown at 10 miles per hour from the car and the car is moving at 60 miles per hour relative to a person standing on the side of the road; relative to the car, the ball is moving at 10 miles per hour, but relative to the person, the ball is moving at 70 miles per hour - these are two different reference frames). Specifically, the mass of an object is related to 1/(1-v/c) [there are some exponentials that I ignored]. So imagine that v (velocity) is 0.999c, where c is the speed of light: 1-0.999c/c = 0.001, 1/0.001 = 1000. If it were 0.9999c, then it would be 10,000 times the rest mass. So as you approach the speed of light, you become infinitely massive.

Now this may not seem like a problem, except that you need to have a force enacted upon you in order to accelerate, and force = mass * acceleration. This means that when mass becomes infinite, the force required to accelerate you becomes infinite. This means that you can never reach c because you would need an infinite amount of force to accelerate you to that speed.

Hopefully this is comprehensible, but if you look into special relativity and relativistic mass you might be able to understand it better. I will include a link to hyperphysics in the source, which has some more clear mathematics.

Answer 4

In theory it is true that accelerating matter to the speed of light is impossible.

As one gets closer to the speed of light, relativity dictates that mass increases. Thus, it would take ever increasing energy to accelerate the ever increasing mass - forming a conundrum.

All this said - people tend to 'poo-poo' the idea of interstellar travel at relativistic velocities (a meaningful percentage of the speed of light). I think this is short sighted.

If we ever commit to scientific exploration like we did in the past (Manhattan project, Apollo program) we might be able to experiment with relativistic space probes. Indeed, a big gun in orbit (a 'rail gun' which uses electromagnetic propulsion) could imaginably launch an interstellar 'Sputnik' with technology available today - it wouldn't do much except perhaps send signals back for a while - but that would be so inspiring and allow us to explore relativistic space travel; even a 10th the speed of light would have an impact on the passage of time for the probe.

KEEP STUDYING SCIENCE - AND DON'T STOP BELIEVING IN THE FUTURE! Also, don't vote for religious fanatic whack job zealots like George W. Bush in the future. He is the worst President in modern American history and a monumental failure.

Answer 5

I have another take on this. I'll admit that I haven't had much success convincing people. So take it with a grain of salt.

Keep in mind that the whole point of "relativity" (when speaking of speed, in particular) is that the speed of an object can have almost infinite variations depending on the frame of referrence. An example would be two objects, both receding from, say, us. One is travelling at speed X, the other is travelling at speed 2X. To a person onboard object A (2X) the Earth would seem to be receding at speed 2X and object B would seem to be receding at speed X. To a person onboard object B (X) object A and the Earth would both be receding at speed X. In opposite directions, yes, but there would be no 2X involved for them. To keep this brief I won't go on with examples. But with a bit of thought you could conceive other examples with other multiples of X, getting into higher and higher speeds. And you'll soon come to examples where an object is travelling faster than light from the standpoint of some objects, yet travelling slower than light from the standpoint of others.

So, how do we resolve this seeming paradox? Well, consider how we measure the speed of an object. We use the Doppler effect. The light waves that reach us from a receding object are "stretched" by this movement. This stretch is measured and that gives a measure of the objects speed. If you imagined an object receding at more than the speed of light, the light that it emits toward us would be "red shifted" as far as it can be. Red shifted right down to zero, as a matter of fact. The light that it emits would simply not have enough energy to reach us. It would be all used up in trying to overcome this "speed gap".

I am convinced that this is what Einstein meant; when an object breaks the speed of light, relative to us, the "information" that we would normally use to perceive it will be lost and can not reach us.

Don't forget also, that if an object were pictured as moving faster than light relative to us, there would still be plenty of objects in the universe that it would be moving less than the speed of light, relative to them. So which is the "real" speed?
Neither. That's another point of relativity; there's no such thing and one frame of referrence is just as valid as another.

In fact, it was a failed attempt to measure Earth's "absolute motion" that got him to think about these things at all.

A summary might be; it's entirely conceivable that there are objects moving faster than light, relative to us, but there is no way for us to "spot them". Relative to us, they are not emitting light, you might say.

but this beautiful line of reasoning does have a flaw that I've never been able to get a handle on; what about an object that is moving toward us at some faster than light speed? It's light would have to be "blue shifted" for us. Would it be blue shifted up into some super high frequency that we have never given any thought to. Is there even an upper limit to this?
Can light be blue shifted to the point that it is not perceivable?
That would seem strange.

Answer 6

Yes, it's impossible. Suppose you flick a particle at 50% the speed of light (ie 50% c). Now you flick it again only 3 times as fast. Common sense says that its speed will be 150% c but what actually happens is that it only goes at about 90-95% c. This is valid with Einstein's theory of special relativity and countless experiments. c is the cosmic speed barrier and is unbreakable whatever sci-fi tells you.

Answer 7

Current theories are such. But as in the past as we learn more and become more technologically advanced, this will just be a barrier that we have to pass. So someone will challenge that theory.

As with the sound barrier and the theories involved there with the ideals of the planes would break apart and other things happen. None of it did, we broke that barrier and we will head to this one as well.

Theories are that a theory. An idea about something, not actual fact entirely as we haven't really got there and we are not technologically advanced enough to really challenge the theory. Although we currently have devices that can give us an idea, we are not quite there yet. We'll see what happens in another 10-20 years.

Answer 8

It follows from Einstein's E=M*C^2; which says that ability (E) is comparable to mass (M) prolonged via the cost of the cost of sunshine (C=3 hundred,000,000 m/s) squared. Or, thinking approximately it yet in a various way mass is purely exceedingly concentrated ability. one way of thinking approximately what occurs once you attempt to enhance up an merchandise to the cost of sunshine is that when the speed will advance it starts off to hold mutually kinetic ability, a number of this ability is became into better mass. The extra mass the merchandise obtains, the extra ability it takes to advance the speed the subsequent volume. So much extra ability ought to be further, that's became into much extra mass. This technique retains repeating itself till, in case you need to attain the cost of sunshine, a limiteless volume of ability could be required to get to the cost of sunshine, with the aid of fact on the cost of sunshine the mass could be countless. so which you would be able to no longer attain the cost of sunshine except you have an source able to producing a limiteless volume of ability. The equation a million/2*m*v^2 is purely an approximation for the kinetic ability, valid whilst the speed is plenty, plenty, under the cost of sunshine. The "genuine" equation takes the exchange of mass into attention.

Answer 9

The idea that the speed of light is a universal speed limit and not source-dependent is a falsity that was proven wrong back in the sixties when powerful radar signals were bounced off the planet Venus from multiple radar stations around the globe simultaneously. As Bryan G. Wallace showed, signals from the side of the earth rotating towards Venus came back sooner than those from the side rotating away, to a degree that fits source-dependent models: http://www.ritz-btr.narod.ru/wallace.pdf

This suggests that [as common sense would have it] the speed of light is additive, i.e. light emitted from a source with velocity v, will have a velocity of c+v on emission. Light is capable of travelling through space with differing velocities. Wallace's observation refutes relativity but unfortunately, by this time relativity had already become more like a religion than science. No career-minded physicist could be seen to be paying heed to a "relativity-denier", so Wallace's paper did not get the attention it deserved and no further investigation was made. The mainstream scientific community carried on believing in the fallacy that the speed of light is always constant.

There have been other astronomical observations that suggest source-dependence too like this: http://www.news.ucdavis.edu/search/news_detail.lasso?id=8364
But such observations are seen as some minor curiosity and the theorists will bend over backwards to invent any kind of fantastical nonsense to explain them so that they can avoid ditching relativity.

The time-dilation seen in type 1a supernova is likely down to light being source-dependent too (rather than expanding spacetime!). And, many apparently variable stars may well be binaries in which light bunching is occurring as faster light emitted from a star moving at it's maximum velocity towards us in it's orbit, catches up with slower light it emitted later: http://www.datasync.com/~rsf1/binaries.htm

Experiments on earth can give the illusion of source-independence but that is due to the EM fields of the earth's matter interfering and effectively normalizing the speed of light from a moving source (i.e. slowing it down to c almost as soon as it is emitted). You have to look at astronomical and interplanetary observations to see how light really behaves. It's planet-bound behaviour is the special case.

There is no mass increase with velocity either. It is only charged particles in a particle accelerator that become more diffcult to accelerate with increasing velocity, i.e. as they approach the propagation speed of the accelerating field (c with respect to the static accelerator). Nothing to do with increasing mass though — this page gives the common sense explanation: http://www.alternativephysics.org/book/RelativisticMass.htm (specifically the "Wind Tunnel" section)

Answer 10

It is indeed impossible. A photon of light has no mass. The mass of any other object increases as it approaches the speed of light. At the speed of light, its mass would be infinite - as would the energy required.