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# Looking for educated help on relativity.

Fri 23 Feb, 2018 01:29 pm
So my question has to do with the relativity (or lack thereof) of the speed of light. We are told that the speed of light is the cosmic speed limit and that it is not relative. This means that anyone moving at any speed will get the same speed for C. So when dealing with the speed of light, speeds are not additive (i.e. I am traveling at half the speed of light and shine a flashlight, that light is still only moving at 186,000mps. So if speeds are not additive in this way, how are we moving apart from other galaxies at faster than the speed of light. I am aware of the warping of space and all, but this part is bugging me for some reason. I know logically that two things moving at the speed of light in opposite directions should be moving away from each other at a rate of 2c. Is it because neither of them are moving faster than light? So i guess the root of the question is, if the speed of light is not relative, how are the galaxies moving farther apart at faster than the speed of light? My first thought is that like the 2c explanation, neither individual is moving faster than light, only relative to each other. But then how does this not violate the relativity of C rules?
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Type: Question • Score: 6 • Views: 1,422 • Replies: 40

View best answer, chosen by jdunlap
rosborne979

4
Fri 23 Feb, 2018 03:32 pm
@jdunlap,
jdunlap wrote:

So my question has to do with the relativity (or lack thereof) of the speed of light. We are told that the speed of light is the cosmic speed limit and that it is not relative. This means that anyone moving at any speed will get the same speed for C. So when dealing with the speed of light, speeds are not additive (i.e. I am traveling at half the speed of light and shine a flashlight, that light is still only moving at 186,000mps. So if speeds are not additive in this way, how are we moving apart from other galaxies at faster than the speed of light. I am aware of the warping of space and all, but this part is bugging me for some reason. I know logically that two things moving at the speed of light in opposite directions should be moving away from each other at a rate of 2c. Is it because neither of them are moving faster than light? So i guess the root of the question is, if the speed of light is not relative, how are the galaxies moving farther apart at faster than the speed of light? My first thought is that like the 2c explanation, neither individual is moving faster than light, only relative to each other. But then how does this not violate the relativity of C rules?

There is a big difference between the speed of light through space and the inflation speed of space itself.

When you hear that we are moving away from galaxies at faster than the speed of light, it's because of spacial inflation, not "speed".
jdunlap

0
Fri 23 Feb, 2018 03:42 pm
@rosborne979,
Ok, that is kind of what I thought, only I called it warping. Should have said inflating. So then it is possible to go faster than the speed of light, just not "actually traveling" faster than light. Like a way of expanding and contracting space to essentially bring "whereever" you are going, to you instead? Although that would probably be impractical because of energy requirements. I know this is more science fiction than anything, at least at the moment, but it seems to fit.
ekename

1
Fri 23 Feb, 2018 08:26 pm
0 Replies

fresco

1
Sat 24 Feb, 2018 02:43 am
@jdunlap,
The fact that you put "actually traveling" in inverted commas points to a significant issue in the philosophy of science...that of 'scientific realism' versus 'theoretical cohesion'. Philosophical pragmatists, like Richard Rorty, dismissed the 'realism' issue in science in favour of 'what works'...a move in line with Nietzche's point that all we ever have is 'description' and some descriptions are merely 'more useful' than others.
(Niels Bohr's celebrated argument with Einstein about 'the reality status of sub atomic particles' is a further example the issue.)
0 Replies

rosborne979

1
Sat 24 Feb, 2018 07:41 am
@jdunlap,
0 Replies

mark noble

-2
Sat 24 Feb, 2018 08:38 am
@jdunlap,
Nassim Haramein.

uploader 'seinfrie ware' (Full HD Copy)
Then watch EVERYTHING of his.
You will never ask a question on physics or reality - Ever again - I assure you.
0 Replies

maxdancona

1
Sat 24 Feb, 2018 09:11 am
@jdunlap,
Ok.... I am a former Physics teacher with a Physics education. These questions frustrate me a little bit because most people responding have no idea of the basics.

If you want a real understanding of this, you have to start at the beginning. You have to understand what the word "Relativity" means. If you don't start here, the rest of the question makes no sense.

The basis of relativity is that the only way to determine the velocity of any object is to specify a frame of reference. If you don't specify the frame of reference, then the whole question makes no sense. You wouldn't know how to measure the velocities of the galaxies you are talking about.

If you are looking for "educated help", we should start with the basics of what we call Galilean relativity. Then we can talk about Einstein and GR.

0 Replies

maxdancona

1
Sat 24 Feb, 2018 09:32 am
@jdunlap,
Quote:
I know logically that two things moving at the speed of light in opposite directions should be moving away from each other at a rate of 2c.

This statement is not true under special relativity... you would have to use lorentz.
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justafool44

1
Sun 19 Jul, 2020 07:36 pm
@jdunlap,
Except the excuse that claims that those galaxies are not moving at more than light speed, because it space that's expanding, is moronic nonsense.
Its an excuse, not an explanation.
Here are the facts.
We are here, watching something move away at a measured or derived speed of 2c.
It doesn't matter a fig what "imaginary frame of reference" you invent, the relative speed differential is still 2c.
Saying that the object is not moving, but the nothing in between (the space) is expanding, and space CAN go faster than c, is nonsense.
That's like saying that the bullet from my gun is not really moving anywhere, but the gas between the bullet and my gun is expanding!

That's like claiming that the plane is not moving in the sky, its the sky expanding. However, EVEN IF it was space expanding, (which its not) how can it both expand AND also SHRINK, giving us red and blue shift?
Further, even if it was space expanding the net result it that it causing that distant star to MOVE AWAY AT 2C! The reason that's its space expanding does not change the fact that the distance between me and that star is increasing at 2c. (for ANY reason, this is an impossibility according to Einstein)

These weak excuses are a feeble attempt to hid the fact that Light speed WILL NOT, CAN NOT ever be measured at still just c, even if we are moving at 75% of c ourselves.
The concept is irrational, and quite impossible.
Blue and red doppler shift of starlight is evidence that we DO measure light speed as c+v and c-v.
In exactly the same way we use wavelength, speed of the radar gun emission to detect relative velocities between that wave and the approaching car.
To say that wavelength is NOT happening at the speed of light is irrational, because that's the principal we use for the speed cameras.

All the weirdness of modern physics can be traced back to Einsteins wacky, quackery of his Theories of Relativity.

mark noble

1
Sun 19 Jul, 2020 07:56 pm
@justafool44,
I agree.

So does Nassim - But other than having measured the mass of the proton and having equated thus as equal to the mass of the (Known) Universe - He claims to have been abducted by ET's and conversed with a 100 delegation of the 'Galactic Federation'.

I believe Him - I mean, Why Not?

Have a Lovely day
justafool44

2
Sun 19 Jul, 2020 08:24 pm
@mark noble,
Is it possible that you might drop the sarcasm and try to post what you actually are trying to say in plain English?
And stop wishing that I have a lovely day, its not genuine so don't say it.
But its a free world, so do what you want I guess. Ill just skip over comments when I see they are yours.

mark noble

0
Sun 19 Jul, 2020 08:48 pm
@justafool44,
No.
Bye.

Have a Lovely day
0 Replies

justafool44

0
Mon 20 Jul, 2020 09:35 pm
@maxdancona,
Yes, under an incorrect model called Lorentz transformation, you will get an equally nonsensical answer.
The call to SR and Lorentz is not Physics, its a faith based belief system.
The rational answer is c+c =2c, c+v and c-v. These are rational equation fragments, and work demonstrably well for Physics.

McGentrix

0
Mon 20 Jul, 2020 10:30 pm
@justafool44,
justafool44 wrote:

The rational answer is c+c =2c, c+v and c-v. These are rational equation fragments, and work demonstrably well for Physics.

I'd like to just admire that for awhile.
justafool44

0
Tue 21 Jul, 2020 12:16 am
@McGentrix,
it sure beats the equation of Lorentz, and the difference is that the idea behind these equations, (v' = c +v and v' = c -v) is that the hypothesis is rational and does not require magic.
0 Replies

maxdancona

2
Tue 21 Jul, 2020 09:21 am
@McGentrix,
McGentrix wrote:

justafool44 wrote:

The rational answer is c+c =2c, c+v and c-v. These are rational equation fragments, and work demonstrably well for Physics.

I'd like to just admire that for awhile.

I am going to bet that he can't even explain his own equations. What experiment could you do to show the c+c = 2c?

And what does "c" mean anyway? It doesn't even make sense.

I wonder how Justafool would suggest we measure "c"?
justafool44

1
Tue 21 Jul, 2020 06:22 pm
@maxdancona,
Well that really ironic.
A person who thinks that no mater how fast or even in what direction a moving observer is going relative to light, he would still MAGICALLY and INEXPLICABLY measure light at velocity c relative not only to him, but to every other moving thing at the same time, is saying that my far simpler and logical explanation "does not make sense".

As we have never measured Light in as a "one way" measurement, or demonstrated that light always goes at c relative to ANYTHING and EVERYTHING, we are hardly in a position to measure what c + c might be. But we do know that for EVERY other thing that moves, V=V=2V, and that IS verified. There is no reason to believe that this is not suddenly correct for light.

On one hand you claim that light is not relative to the source, then immediately you contradict yourself when you claim that its immutable velocity IS measured at that set velocity relative to the observer, WHO IS HOLDING THE SOURCE, so in that instance, light IS relative to the source!

I wish you crazy relativists would pick a side , and stay with it. Having a foot in every possible camp is cheating. You can never be wrong, as you get to change feet at will.

maxdancona

1
Tue 21 Jul, 2020 06:23 pm
@justafool44,
You can't define what "v" is. How can you do any any math with it?

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