I need time dilation help please?

With your level of mathematical knowledge there is an approximately zero chance you understood what was said. The language of physics is mathematics.

With your level of mathematical knowledge there is an approximately zero chance you understood what was said. The language of physics is mathematics.

You will find relative to an inertia reference frame a proper length is referred to as it's rest length also used in relativity.

In imagination, imagine standing on a central platform between two trains, one train on the left and one train on your right. We measure both trains to be an equal rest length of lets say 50 meters. Now if the trains travel at the same speed away from you and parallel to each other, the observer on the platform witnesses a length contraction of both trains, people on the trains still measure the trains to be at rest length relative to each other.

The train the people and their ruler have contracted , so they still measure 50 meters.

Indeed.




Yep. We measure the trains to have contracted because we're moving relative to them. The people on the first train aren't moving with respect to the train so still measure its rest length. The same holds for the second train.




Well in their reference frame the people on the train haven't contracted and nor have their rules. But yes if we watch them measuring their train, it will look to us as if both their rulers and the train have contracted so they'll measure 50m.

No real disagreement so far!

Ok, so half way through the journey one of the trains breaks down, and the other train continues its journey. The observer on the platform gets on his bicycle and decides to travel tot he broken down train to confirm his original measurement of 50 meters, He arrives to confirm the rest length is 50 meters, but was curious about the contraction they had just observed, So in being a scientist , the observer placed two sensors on the stationary train , one at the front and one at the rear to record the returning passing trains measurement by sensor alignment What do you think the result was?

Can we clarify precisely what the sensors are measuring?

The sensors are measuring alignment

but we already know they will align because the trains travelling parallel in motion measured the same .

The fact that they are the same length (which is what I assume you mean by alignment i.e. check that when the fronts are aligned the backs are also aligned) when they are stationary with respect to each other does not necessarily mean that they are the same length when one is moving relative to the other. We need to check this; otherwise we are presupposing that there is no length contraction.

Yea you got this, you understood, I already know there will be no contraction you can check,

The sensors are measuring alignment , but we already know they will align because the trains travelling parallel in motion measured the same .

If you have legitimately performed this experiment and think you have found no length contraction, I have two things for you to consider. First, think very carefully about precisely how you measure the 'alignment'. It's very easy to say things like 'oh we'll just use a lightgate and measure the time it spends clicked off', but you have to be very careful to ensure you consider everything relativistically. It's very easy to forget this when you consider the time taken for light signals to move between sensors and objects etc. More importantly, to what precision did you run the experiment? The factor by which lengths contract and times dilate is denoted by $\gamma$, and is given by

$\gamma=\dfrac{1}{\sqrt{1-\frac{v^2}{c^2}}}$.

The UK high-speed trains go at a maximum of 300kmph, which is roughly 85 m/s. So even if you ran the experiment with trains that went this fast, you'd be looking at a gamma factor of

$\gamma=\dfrac{1}{\sqrt{1- \Big(\frac{85}{300,000,000} \Big)^2}}$.

It's very unlikely that your calculator will be powerful enough to even compute this number, and will just tell you that there is no change. The exact factor by which the train would contract at such a high speed is 1.0000000000000402. For a slower speed this would be even closer to 1 (no change). Was your equipment sensitive enough to notice this? Was it the change outside your error tolerances? For equipment that measured values to a precision of 1 in 1,000,000,000,000, you wouldn't measure a difference even if there was one! Your equipment just wouldn't be good enough for the job! You'd need much higher speeds or much better equipment.

The detectors will see that the trains will not be perfectly aligned.

How would you try to explain this -

For an object to contract in length. the rear has to be travelling faster than the front.

All the maths in the world doe's not explain reality, I have not tried this experiment, but there is without an uncertainty I know I am correct. Physical contractions involve forces, I do not consider air is an equal and opposing force to contract molecular structure that is dense. There may be some expansion and contraction in the overall form involving thermodynamics, but there is cert is not the way you imagine.

You are correct I should hold judgement until something like this is tested, but I am sure I am right.

Now this is a good idea

I know lol,



Phys 101

If you are defining a physical contraction to be one involving forces, then indeed special relativistic length contractions are not 'physical contractions'. But this is not a definition used by anyone else in physics so isn't very useful. In fact, we really do observe that the molecules making up a solid are closer together when viewed from a reference frame in which the solid is moving. If you like, you can pass this off as a 'visual distortion' - which in some sense it is. But these distortions are a fundamental part of space and time, and the fact is that in frames where certain objects are moving, those objects interact with the rest of the universe as if they are shorter than they are in their own frame. It isn't just humans who 'see' a difference.




The problem is that SR has been tested and confirmed many times. Maybe not using an experiment identical your own, but the same principles have been used and special relativity confirmed.

It puts great strains on a lot of science, and as yet nobody has proven any of this to be wrong.

Scientists do not submit 'theories' then proclaim to the world "Go ahead and prove me wrong".
That is not how it works and is childish.
YOU need to back your theories with either proof or predictions.

It is obvious you have limited formal education in physics.