# SR is that nothing can move faster than light

• nieuwenhuizen
In summary: The result is c-u=u-v. However, this is only true if the speed of light is the same in all inertial frames of reference. If not, the result would be different.
nieuwenhuizen
Can somebody explain my error to me?

1. The base of SR is that nothing can move faster than light, c + v == c,
c - v = c

2 The next step many authors do is proving non-existance of simultaneity by
on observer at the platform versus one in a fast train. Flash from the
front, to be received at the tail, which is. they say "racing toward the
rays". Conclusion: Speed of approach is $c+v$ so that
$$( c + v ) \cdot \Delta t = L$$
Combination with a forward flash [ c - v ] leads to

$$\frac{1}{c+v} + \frac{1}{1-v} = \frac{1}{c^2 - v^2 }$$

Why does this not contradict the base - statement 1 ?

Thanks to the one that does.

Nieuwenhuizen, J.K.
2009-02-16T15:36

nieuwenhuizen said:
Can somebody explain my error to me?

1. The base of SR is that nothing can move faster than light, c + v == c,
c - v = c

2 The next step many authors do is proving non-existance of simultaneity by
on observer at the platform versus one in a fast train. Flash from the
front, to be received at the tail, which is. they say "racing toward the
rays". Conclusion: Speed of approach is $c+v$ so that
$$( c + v ) \cdot \Delta t = L$$
Combination with a forward flash [ c - v ] leads to

$$\frac{1}{c+v} + \frac{1}{1-v} = \frac{1}{c^2 - v^2 }$$

Why does this not contradict the base - statement 1 ?

Thanks to the one that does.

Nieuwenhuizen, J.K.
2009-02-16T15:36
I am new to this and this is only to find how a reaction is handled. Sorry

nieuwenhuizen said:
Can somebody explain my error to me?

1. The base of SR is that nothing can move faster than light, c + v == c,
c - v = c

2 The next step many authors do is proving non-existance of simultaneity by
on observer at the platform versus one in a fast train. Flash from the
front, to be received at the tail, which is. they say "racing toward the
rays". Conclusion: Speed of approach is $c+v$ so that
$$( c + v ) \cdot \Delta t = L$$
Combination with a forward flash [ c - v ] leads to

$$\frac{1}{c+v} + \frac{1}{1-v} = \frac{1}{c^2 - v^2 }$$

Why does this not contradict the base - statement 1 ?

Thanks to the one that does.

Nieuwenhuizen, J.K.
2009-02-16T15:36

No body can travel at greater than c, but there's no problem with the distance between two moving bodies closing at more than c. Two bodies approaching each other, each at nearly c in the observer's frame, will close distance at nearly 2c. Of course, in the frame of reference of one of the bodies, the distance is closing at nearly c, not nearly 2c, because all of the motion is in the other body, which cannot travel faster than c.

nieuwenhuizen said:
Can somebody explain my error to me?

1. The base of SR is that nothing can move faster than light, c + v == c,
c - v = c

2 The next step many authors do is proving non-existance of simultaneity by
on observer at the platform versus one in a fast train. Flash from the
front, to be received at the tail, which is. they say "racing toward the
rays". Conclusion: Speed of approach is $c+v$ so that
$$( c + v ) \cdot \Delta t = L$$
Combination with a forward flash [ c - v ] leads to

$$\frac{1}{c+v} + \frac{1}{1-v} = \frac{1}{c^2 - v^2 }$$

Why does this not contradict the base - statement 1 ?

Thanks to the one that does.

Nieuwenhuizen, J.K.
2009-02-16T15:36
Consider please the following experiment performed in an inertial reference frame in the limits of Newton's mechanics. A source of light S located at the origin O emits successive light signals in the positive direction of the x-axis at constant time intervals t(e). The light signals
illuminate a target that moves with speed u in the positive direction of the x axis. When the first signal is emitted the target is located in front of the source. We impose the condition that the second emitted signal illuminates the target at a time t(r) i.e.
c[t(r)-t(e)]=ut(r).
where from
t(r)=ct(e)/[c-u]
Special relativity is not involved so far. Is c-u the result of a classical sddition law of velocities? That is the way in which the classical Doppler Effect formula is derived.

## 1. Why is the speed of light considered to be the universal speed limit in special relativity?

In special relativity, the speed of light is considered to be the universal speed limit because it is a fundamental constant in the universe. According to Einstein's theory, the laws of physics are the same for all inertial observers and the speed of light is the same for all observers, regardless of their relative motion. This means that nothing can move faster than light without violating the laws of physics.

## 2. Can anything ever travel at the speed of light?

No, according to special relativity, it is impossible for any object with mass to reach the speed of light. As an object's speed approaches the speed of light, its mass increases infinitely and it would require an infinite amount of energy to accelerate it to that speed. This is why the speed of light is considered to be the upper limit for the speed of any object in the universe.

## 3. What happens if an object exceeds the speed of light?

According to special relativity, it is impossible for an object to exceed the speed of light. If it were to happen, an object would require an infinite amount of energy and its mass would become imaginary, which is not possible in our physical world. This is known as a violation of causality, meaning that an object would be able to travel back in time, which goes against the laws of physics.

## 4. Is it possible for information to travel faster than the speed of light?

No, according to special relativity, information cannot travel faster than the speed of light. This is because information is carried by particles and waves, which are subject to the universal speed limit of light. Even if an object were to somehow exceed the speed of light, it would not be able to transmit information faster than the speed of light.

## 5. Are there any exceptions to the rule that nothing can move faster than light?

Currently, there are no known exceptions to this rule in the context of special relativity. However, there are some theories, such as quantum entanglement, that suggest the possibility of particles being connected in a way that allows information to be transmitted instantaneously. However, this is still a topic of debate and has not been proven conclusively.

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