Why can't you go faster than the speed of light?

Question

If I was on a train moving 2 miles an hour below the speed of light and then took a step forward, why wouldn't I be moving at the speed of light?

Answer 1

The question you really have to ask is who you are travelling relative to.

If you were travelling on your train that was travelling away from me at 2 miles/hr below the speed of light and then you walked along the train at 2 miles/hr relative to the train, the question you have to answer is how much faster you are walking relative to me.

At the end of the 19th century experiments started to show that everyone gets the same result for the speed of light, regardless of how they are moving. This means that on your train if you turned on a flashlight then the light would move away from you relative to you and the train at the speed of light, and it would also move away from me at the speed of light. This is not what you expect from simple ideas of adding speeds, but it is how the universe actually behaves.

So when you walk down the train you will indeed be walking at 2 mph relative to the train, but relative to me your speed will not add to the speed of light or more - not even light can pull off that trick. Einstein showed that speeds actually add differently by a factor of sqrt(1 - v^2/c^2). For normal speeds v is much less than c and so this is 1. For very high speeds it is zero.

Answer 2

There is more than one part to this answer.

Firstly, we are talking about the speed of light in a vacuum. This is the limiting factor. Light itself does not have a fixed speed.

There might be things that can travel at speeds greater than the speed of light. There are posited particles called tachyons that ALWAYS travel at super-luminary speeds. They do not have mass. They have not been observed, proven or disproven, but they form part of various hypotheses.(See Tachyons/Wikipedia)

It is not possible for any vehicle to travel at speeds approaching the speed of light, according to Special Relativity. There is a problem with mass: as it approaches the speed of light it increases, so that it approaches infinity. You would need an infinite amount of energy to accelerate an object with mass to the speed of light. You also run into problems with cause and effect, where the effect occurs before the cause. Various ways have been suggested to overcome these problems, but this is mainly the realm of science fiction. They almost all require a completely new or different understanding of reality. Some of these might work, but we are far from being able to even say which ones this might be.

If you were on a vehicle travelling at say 1km/h below the speed of light and you travelled at 2km/h, you would travel at 2km/h, not at (speed of light + 1km/h). It doesn't work like that. You cannot just add the numbers together. Besides if your mass was approaching infinity, you would find it very difficult to move at all. In fact, it is hard to see how you could even stay alive.

Einstein never said that nothing could go faster than light, but it was assumed to be so for the purpose of constructing his equations. Relativity is a model of the Universe, the best we have at the moment. This work will no doubt be superseded in the future, other models will be formed. It is impossible to predict what might or might not be possible with these new models.

Answer 3

Massive objects can't accelerate to the spped of light because of something known as "relative mass". Einstein said that when an object move at different speeds, its mass differs: the faster you go the heavier you get. The effect is only apparent at very, very high speeds close to the speed of light. As you get closer and closer to the speed of light, your mass increases exponentially. For example at 99% of the speed of light, an object which weighs 100kg at rest will weigh 709 kg. The same object would way 2240kg at 99.9% the speed of light, and so on.

The relative mass can be calculated by the following formula:
m = (m0)/{sqrt[1 - (v^2/c^2)]}
where:
- m is the relative mass
- m0 is the mass of the object at rest
- v is the speed of te object
- c is the speed of light.
(sqrt stands for square root).

A close look at the formula shows you that when the objects speed (v) reaches the speed of light (c), the formula becomes like this:
m = (m0)/[sqrt(1 - 1)] since v = c, v^2 = c^2
m = (m0)/[sqrt(0)]
m = (m0)/0 since sqrt(0) = 0
m = infinity (division by zero).

So now, you can see that when an object reaches the speed of light, it's mass becomes infinite. A very famous formula of Einstein's goes: E = mc^2. In other words mass (m) and energy (E) are equivalent. More mass means more energy, and vice-versa. Hence, to move an object of infinite mass you need infinite energy. Sadly, there's no such thing as infinte energy.

Scenarios like the ones you propose are one of the complex aspects of relativity. After Einstein postulated that c was constant that was also the universal speed limit, he realized that other factors had to change to accomodate this constantness. Time and distance both change to make sure that for any observer no matter what conditions she is experiencing will always measure the ultimate speed at c. The problem is you're imagining the scenario as if you're in a bus enjoying your everyday. If you're 2 mph below c then I can assure you, things are very very different. For one thing, time is almost at a stop, and everything outside your train looks weird and distorted. The point is it's not as simple as "taking a step forward" to violate the universal speed limit, cuz you're unfortunately all the laws of physics will do everything in their power to prevent you from doing that. Consipracy theory anyone?

Answer 4

One of the prediction made by the theories of relativity is that an object's mass increases as it moves faster and faster. The effect is only of significance at speeds approaching that of light Hence, it becomes more difficulty to make that object move faster and faster. Near the speed of light it can't be done. In your scenario, you couldn't make that step. The maths is complicated!

Answer 5

You would have to step forward at 2 miles per hour. Then you would be travelling at the speed of light. Unfortunately , no train can get you to this speed in the first place. If we could travel at this velocity then we would be taking vacations on planet zog. What I want to know is, why cant I hear at the speed of light????

Answer 6

The answer is relatively simple (no pun intended). you likely would be traveling in a rocket ship rather than a train 9because of the vacuum of space). You could increase the speed of the rocket (accelerate) as long as you can eject gas, ions or even photons) from your tailpipe traveling faster than your rocket ship. Unfortunately, nothing has been observed in the Universe traveling faster than the speed of light and all photons travel at exactly the speed of light. As you approach the speed of light you can eject only photons traveling at the speed of light and they can never make you travel faster than they are traveling while being ejected. At anywhere near the speed of light your rocket ship would have to expend tremendous amounts of energy (more than you could store on board) to get even a little extra push. As the rocket ship goes faster and faster it contains more and more kinetic energy. That energy is equivalent to mass using Einstein's equation E = mc2. At the speed of light the rocket ship must attain infinite mass, yet it can have no more mass than it had at the start of the flight.

Answer 7

light has no mass, it is part electromagnetic spectrum. In order to travel faster than the speed of light an object must have no mass. For humans, this is impossible.

One day I will be smarter than Einstein and finally work out a way to travel as fast or faster than the speed of light. Nothing is impossible on this planet. We just don't understand it fully yet.

Answer 8

Einstein's theory of relativity says that for you to be travelling at the speed of light, your mass must be infinite or zero which is a physical impossibility.

Given that we are currently moving slower than the speed of light, we must at somepoint be moving at the speed of light in order for us to attain a speed greater than the speed of light.

The problems with mass will prevent physical matter from travelling at the speed of light and consequently we will never be able to travel faster than the speed of light.

Answer 9

The warp force works by making use of the indisputable fact that even nevertheless rely or something with mass can not return and forth speedier than gentle, area itself can. which ability that is no longer the deliver that strikes, that is area that strikes by making use of the enterprise collapsing the area in front of the deliver and increasing the area in the back of it. in fact it shortens the area from gentle years to three hundred million kilometres. As to the G forces, there are not any G-forces to to rigidity approximately. The warp force isn't a great effectual antimatter rocket, yet an engine that strikes area. and because that is area that strikes and not the deliver, then there are not any G-forces by way of fact the deliver would not boost up.

Answer 10

In a sense we can travel faster than the speed of light by using the bent space theory.