show me proof then that there are more than 4 dimensions?
someone had to go round the world to prove it wasn't flat at some point, so if you can show me hard evidence that a 5th or more dimension actually exist then I'll believe it.
show me proof then that there are more than 4 dimensions?
someone had to go round the world to prove it wasn't flat at some point, so if you can show me hard evidence that a 5th or more dimension actually exist then I'll believe it.
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I
imamartian
Joe, you seem to have respect on this site... too much respect in my book.... go and create you own thread for making banal comments on please... and leave my threads alone !!
I
imamartian
show me proof then that there are more than 4 dimensions?
someone had to go round the world to prove it wasn't flat at some point, so if you can show me hard evidence that a 5th or more dimension actually exist then I'll believe it.
ColJ, i get what you're saying, but we thnik time is the 4th dimension? but time changes according to ..... gravity? speed?
the point is..we can't prove anything can we?
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You only started this particular discussion martian. You don't own it or have control over where it goes. Just like real life really.
J
joinerjohn
I went on holiday once ,,,,,,, and almost dropped off the end of the world!!
At least that's what it seemed like, when I realised that my wallet had been stolen.
When I got back I filled the insurance forms in and got most of my money back
I
imamartian
You told joe to basically get off your thread. It's not your thread, you only started it and now it's everyones to contribute to as they like within reason. The only editors are the mods, not the OPs.
M
malcolmX
naughty.
M
malcolmX
I used to push my old handcart round the streets of Manchester at a snails pace
To get back to the original question ---
The whole time-dilation business came out of Einstein's solution to a problem that had nothing to do with clocks. Physicists had a problem in as much as they had been unable to find any fixed frame of reference against which to measure absolute velocity. There was no possible way to find out who was moving and who was stationary.
Einstein's fundamental postulate was that the laws of physics were the same for all inertial observers, an inertial observer being one who is travelling at constant velocity. If you couldn't tell who was moving, you couldn't tell who was getting the right answers so maybe they all are. It was a very plausible assumption but it had some unexpected consequences.
Question: What happens when two observers try to measure the speed of the same light beam? The light is travelling from the back of a moving train to the front. One observer is on the train while the other is on the ground. Common sense dictates that they must get different answers. The train will have moved forwards while the light makes its trip and so, as seen from the ground, the light must travel further.
Problem: Maxwell had already shown that the speed of light could be derived in a simple way from two physical constants, namely the permeability and permittivity of free space. Both of these constants can be measured in the lab and so, according to Einstein, both observers must get the same answers.
To get round this paradox, Einstein had to throw away the idea of absolute time. This was the only way to make the speed of light the same for all inertial observers. As seen from the ground, the clock on the train appears to run slow, and not just because it's moving. If you set up a pair of synchronized clocks along the track, you can check the moving clock against each one as it passes. It will be running slow. On the other hand, as seen from the train, a clock on the ground will run slow.
It gets even more complicated because, ridiculous though it may seem, a moving object shrinks in the direction of motion. If you measure the length of the train as it passes, it will be shorter than if it was stopped. Moreover, as seen from the train, a station will also appear shorter as it goes past.
When all of this is put together, something else drops out because the old law of conservation of momentum doesn't quite work. We can either abandon the law - which no physicist wanted to do - or modify the definition of momentum. Instead of P = m x v, it becomes
P = m x v /sqrt(1 - (v/c)^2)
If you look at this equation, you will see that momentum tends to infinity as you approach light speed. This effect is usually described by the rather dubious claim that "the mass goes up". If this forum was better suited to writing mathematical equations - and if I could be bothered - I could go on to derive what is probably the most famous formula in physics: E = mc^2.
The whole time-dilation business came out of Einstein's solution to a problem that had nothing to do with clocks. Physicists had a problem in as much as they had been unable to find any fixed frame of reference against which to measure absolute velocity. There was no possible way to find out who was moving and who was stationary.
Einstein's fundamental postulate was that the laws of physics were the same for all inertial observers, an inertial observer being one who is travelling at constant velocity. If you couldn't tell who was moving, you couldn't tell who was getting the right answers so maybe they all are. It was a very plausible assumption but it had some unexpected consequences.
Question: What happens when two observers try to measure the speed of the same light beam? The light is travelling from the back of a moving train to the front. One observer is on the train while the other is on the ground. Common sense dictates that they must get different answers. The train will have moved forwards while the light makes its trip and so, as seen from the ground, the light must travel further.
Problem: Maxwell had already shown that the speed of light could be derived in a simple way from two physical constants, namely the permeability and permittivity of free space. Both of these constants can be measured in the lab and so, according to Einstein, both observers must get the same answers.
To get round this paradox, Einstein had to throw away the idea of absolute time.
This was the only way to make the speed of light the same for all inertial observers. As seen from the ground, the clock on the train appears to run slow, and not just because it's moving. If you set up a pair of synchronized clocks along the track, you can check the moving clock against each one as it passes. It will be running slow. On the other hand, as seen from the train, a clock on the ground will run slow.It gets even more complicated because, ridiculous though it may seem, a moving object shrinks in the direction of motion. If you measure the length of the train as it passes, it will be shorter than if it was stopped. Moreover, as seen from the train, a station will also appear shorter as it goes past.
When all of this is put together, something else drops out because the old law of conservation of momentum doesn't quite work. We can either abandon the law - which no physicist wanted to do - or modify the definition of momentum. Instead of P = m x v, it becomes
P = m x v /sqrt(1 - (v/c)^2)
If you look at this equation, you will see that momentum tends to infinity as you approach light speed. This effect is usually described by the rather dubious claim that "the mass goes up". If this forum was better suited to writing mathematical equations - and if I could be bothered - I could go on to derive what is probably the most famous formula in physics: E = mc^2.
M
malcolmX
Space Cat,
You have lost me.
You have lost me.
MalcolmX said:
That's not unusual. I got lost myself when I first studied relativity. I think the whole class did. I was convinced that it was all a big mistake and there had to be a simpler solution - as did our daughter in her first year at university. When I told her that there was good experimental data to support the theory, she was horrified because she had made it her mission disprove it!
Here, in a nutshell, is the conundrum:
It is not possible to determine who is moving and who isn't. Are you moving past me or is it me that's moving past you?
Now let's do some experiments to measure some fundamental physical constants. Does our velocity matter? If it does then we have a problem because we won't know which of us is right. Einstein suggested that we would both get identical results - and experimental evidence bears this out.
Now lets do an experiment to measure the speed of light on two identical trains. Mine is static and yours is moving past it. As the back ends of the two trains pass each other, a spark jumps between them and we each measure how long it takes the light to reach the front of our own train. Note that we are both measuring the same light.
Now it is obvious to me that it must reach the front of my train first because, by the time it gets there, yours has moved on. So your answer will be wrong - or will it? You saw my train coming backwards towards you and so the light reached the front of it a bit too early. As far as you're concerned, it's me that's wrong.
We could solve the problem if light travelled at a constant speed through some invisible medium, namely the hypothetical aether. If we both took our own velocities through this aether into account, we would get identical results.
The problem was that no such aether could be found. On the contrary, experiments with light from distant stars proved beyond reasonable doubt that there was no such thing.So there we are, each getting a different answer for the speed of the same light, even though we can do other experiments to show that we should get identical answers.
There was one other way out of this mess and Einstein took it; he stopped assuming that our clocks and rulers were identical. With a nifty bit of mathematics, he showed how we could both get the same answer if a moving clock ran slow and a moving ruler shrank. At this point, half the class wanted to know which clock and ruler were wrong. The rather confusing answer is that it's always the moving one. If I time your clock as it goes past, it will be slow. But if you use that same clock to time mine, it is mine that will be slow! Similarly, your ruler will look short against mine but mine will look short against yours - and if you think all this is just too ridiculous to be true, you are not alone.
Seeing as you're here at the minute spacecat, I have to say I'm not feeling very enlightened here.
I want me money back or I'm putting a complaint in.
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