Is it harder to walk forwards in a moving train than to walk backwards?

Question

Like if you were walking in the same direction as the train would be traveling, so you end up moving faster than the train. is that harder than walking in the opposite direction of train travel.

Im sure most will answer that there is no difference, but that would mean if the train was at light speed it would only take a tiny amount of energy by the traveller to exceed the speed of light.

all hypothetical of course, and let assume the train can get to that speed in the first place.

Answer 1

Makes no difference whatsoever than if you did it on the pavement.
The air around you would be static, being enclosed in a carriage with you.
You would certainly notice the difference if you were on a flatbed as the air would be travelling at the same speed as the locomotive. Therefore air forces would send you flying backwards. Fast!

Answer 2

Excellent question. But first...

If you assume that you get a train up to the speed of light you are creating a hypothetical universe in which the laws of physics of the actual universe are not valid. You have created a science fiction universe and then you can choose the answer for yourself.

Back to the real universe. Let's assume that the train is moving at 99.999...% the speed of light. This is possible in the real universe if you have a lot of energy to get the train up to that speed. Then assuming the train is moving at a constant speed it would be no different to traveling on a train at 30 mph or a train that is stationary. The answer is no it makes no difference which direction you walk it is just as easy.

This is because everything is relative. Speed is relative. If an object is floating in space with nothing else around how do you know how fast is it going? You need another object in the area and then you can measure the speed of the first object relative to the second. But how can you say which object is moving?
The answer is you can't. You chose one and take that as the stationary point. Here on earth we chose the earth as a stationary point and measure speeds relative to the ground under our feet because it is convenient to do so. But this doesn't mean anything.

What I am trying to explain is speed is irrelevant to the laws of physics. It doesn't matter how fast you are going - you can consider yourself to be stationary and everything else to be moving.

After all the earth is moving round the sun at 1040 mph but it is not easier to walk in the direction of this movement than against it. And the sun and earth move through the galaxy at 486,000 mph but you cant tell because it is irrelevant to the laws of physics operating on the earth.

This is one of the postulates of relativity. In physics lingo it is described like this:
The laws of physics are independent of the inertial reference frame in which they are operating.

Answer 3

The rule that says you cannot go faster than light also intends that you cannot get to the speed of light. You seem to be thinking of it as if the train's speed can be less-than-or-equal-to light speed, when it really is restricted to less-than light speed. No matter how close to light speed the train gets, any additional kinetic energy applied will merely bring it an additional fraction closer, but not quite at light speed. The same goes for an object on the train. It can be moved slightly faster than the train, but still won't reach light speed.

Answer 4

It would be the same either way.

Whats more, the speed of light in the train would be - well - the speed of light. So you would be nowhere near reaching it. EVERYONE gets the same result for the speed of light and all motion is relative, not absolute.

If I am an observer and your train is moving close to the speed of light, then as you walk forward the speed you tell me you walk relative to the train and the speed of the train always add to less than the speed of light. The missing energy this implies goes into mass - you gain mass. Relative to me of course. Relative to the train you have the same mass.

Answer 5

If the train happens to be undergoing any acceleration forces, such as going around a curve, there can actually be a difference in effort in walking either direction in the train cars, because there is no rest frame of reference in such a case, Newtonian or as in special relativity. This is probably why train riders sometimes think that it does seem to make a difference, but the effect is tiny.
However, if the train is going straight, and it shoots out a beam of light in either direction, to the observer on the ground outside of the train the beam of light will appear to be going exactly at the speed of light either way. This is because we're actually in relativistic hyperbolic space, even though our common senses tell us that we're in an Euclidean one. We want to believe that our world is Euclidean, but all the experiments on this subject have proven otherwise.

Answer 6

Either. I can feel the difference and I assume it comes from the surrounding air contained within the carriage.
Since the physical mass of the train is progressing at the same speed as its prime mover, the air is constantly becoming compressed at the rear of each carriage.
As it is pushed out by more air arriving, the amount displaced expands and assists anybody who is walking to move easier.
Since there are two distinct movements of compression and expansion it really depends on the time the walking takes place and whereabouts the air cycle lies.

Answer 7

If the train were travelling at the speed of light, and you were walking in the direction the train was travelling, you would (technically) be able to look behind you and see yourself coming towards you.
The only thing that would make your walking on the train more difficult is if it suddenly stopped, accelerated rapidly, or went over a bump.

Answer 8

.but if u move in side the train you are only moving at walking speed. As light speed is concerned you, the air around you and everything in the train are part of the train and therefor part of it. Your movements inside are independent of the outside world

Answer 9

No, since the train imparts its own forward motion, and you only have to add enough to accelerate somewhat.

Thereotically, it would require a small amount more force to cause the same acceleration as if you were starting from rest, since mass increases with velocity. But the increase would be immeasurably small.

As to the speed of light, as you approach that speed your mass increases toward infinity. If you were traveling at that speed, it would require infinite force to cause acceleration of your infinite mass.

Answer 10

Both would be equally impossible from the point of view of an external observer.

To an external observer, if the person were walked forward 10 meters at 1/10th the speed of light (just to keep the arithmetic simple), the person's velocity would appear to be:

(.1c + c)/[1+(.1c)(c)/c^2] = 1.1c / 1.1 = c

If the person were walking backwards, his speed would appear to be:

(-.1c+c) / [1 + (.1c)(c)/c^2] = .9c / .9c = c

The observer would see no change either way. Of course, from the observer's point of view, the 10m inside the train relative to the train has been contracted down to zero:

10m * sqrt (1-c^2/c^2)

If you slowed the train's speed down to .9c, then, at least from an external viewer's point of view, walking backwards might look easier. Walking forwards would increase the person's speed to .918c from the external viewer's point of view while the walking backwards would reduce the person's speed to .87c from an external viewer's point of view. The 10 meters would only be collapsed to .19 meters in this case.