# The Naked Scientists Forum

### Author Topic: Is the speed of light the same to all observers?  (Read 12275 times)

#### yor_on

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##### Is the speed of light the same to all observers?
« Reply #25 on: 30/05/2011 14:32:56 »
Yep time is most important :)
Without it no causality.

Without causality no motion.
==

As for the way you want to narrow it down to 'time'.
I don't know? Go to 'New Theories' and define what you think :)

I see 'time' as one of the most confusing phenomena I know.
But 'times arrow' seems also to be a property directly coupled to 'SpaceTime'.
And it and radiation keeps the same count, to me that is :)

They goes hand in hand, both being 'constants' from your own 'frame of reference'.
Then there is one more thing, we need to differ between 'conceptual truths' and those we actually can measure first handedly. A conceptual truth is a 'time dilation' to me. A measurable truth is that at no time will you find your time to differ, using your wrist watch against your heartbeats for example :)

But write it up in New Theories, and we will see.
« Last Edit: 30/05/2011 14:50:24 by yor_on »

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #26 on: 30/05/2011 15:29:39 »
Hi again Yor_on,

It's all written down in my new book, which I am not allowed to advertise here.

By the way, your comment about time dilation being unmeasurable is incorrect. I agree that WITHIN your frame, your clock rate will never change whether you speed off at "c" or land on a black hole (these are the limits). BUT, relative to other frames your clock certainly DOES change its rate. This IS measureable (Hafele & Keating 1971)
This is all mainstream
« Last Edit: 30/05/2011 15:35:01 by Ken Hughes »

#### yor_on

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##### Is the speed of light the same to all observers?
« Reply #27 on: 30/05/2011 15:50:23 »
You didn't get what I said Ken. I said it was a 'conceptual truth'. It can be confirmed by a twin experiment but at no time will any of the 'frames of reference' find their own 'time' to start behave differently. That's what make it into a 'conceptual truth'.

You have the measurements you can do, and then you have 'frames of reference'.
Try to see what I mean.
==

Btw: You're not using this site to advertise your book, are you?
Because if you are then you're at the wrong place. TNS has a rather strict policy not allowing 'self aggrandizing'. It's mostly a place for questions and discussions :)

As for no 'frame of reference' being the 'exact same' it's been shown beautifully with two atomic clocks, putting one on the floor relative the other still being on a table. And in television no less :) So I have no arguments with that. But if we define you as having only one '¨frame of reference', then that also mean that although you will see the 'clock ticks' start to differ between the floor and the table, your own 'frame of reference' still only will have one same 'clock tick', defined by ? Pick your choice.
« Last Edit: 30/05/2011 16:01:00 by yor_on »

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #28 on: 30/05/2011 16:01:11 »
Yor_on,

If you read my previous response, it is very clear that I do indeed understand what you are saying. "You'll never see any difference in your clock from WITHIN your frame of reference". This we agree on, right?

BUT........ by definition, "Time Dilation" is the RELATIVE change of time rate between frames of reference at different gravitational potentials and/or in relative motion. This is not just a conceptual thing, it is REAL and was proved in 1971 and subsequently.

#### yor_on

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##### Is the speed of light the same to all observers?
« Reply #29 on: 30/05/2011 17:28:08 »
Let me ask you a question, if you went out tomorrow and finding all people one year older than before your coffee break, would you then assume that it was you or them changing? As you drank that coffee? Let's assume that none of those comparing ever found their own time behaving 'different' for this.

And then change view, assume that you were one of those guys being one year older, watching 'you'. Would you then assume that it had been you 'accelerating' your time, or would you assume it was the 'other guy slowing down'?

A time dilation is a effect between 'frames of reference'. It will always be a arbitrarily defined 'system' in where one part, for example making a acceleration, introduce a different 'room time' relative it's counterpart (& origin) by that acceleration. Without another 'frame of reference' to compare that 'time dilation' against there will be no measurable proof, no matter your acceleration, or mass, or energy..

And so it is 'real', but on the conceptual plane. As the guy traveling, your time do not 'change', but your 'positional system' in time and space/room will relative all other comparisons.
« Last Edit: 30/05/2011 17:34:24 by yor_on »

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #30 on: 30/05/2011 18:26:31 »
Hi Yor_on,

It doesn't matter what I might think from either frame of reference, or what others might think from theirs. The fact is that the moving frame's clock (or the one that has been in a low gravitational potential), has lost time relative to the frame it left behind.  This effect is not due to acceleration, but only to the amount of time it spent in the different frame and the difference in time rates between the frames. This is standard Special Relativity. I am not changing it or presenting it any differently than Albert Einstein.

I would be interested to know what you think about length contraction. Do you think this is the same as time dilation, or more real or less real?

#### yor_on

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##### Is the speed of light the same to all observers?
« Reply #31 on: 30/05/2011 19:31:41 »
Yes, we agree on that the frames of reference have changed relative each other :)
But, where did you think the change came about?

Assume that we have three observers. One on Earth, two 'alien observers/spacecrafts' in space.
For this we will use Earth as the 'inertial frame', defining their speeds.

Then assume that both space farer's are moving uniformly. From Earths perspective we don't need to know if they ever accelerated to measure their 'speed', relative our 'inertial earth frame' that is.

Will they see a Lorentz contraction? Will both of the aliens observe the other space-crafts 'clock' to go slower than their own? Will they have a time dilation? What will define that 'time dilation'?

In a uniform motion all motion becomes unmeasurable inside a 'black box scenario'. You trying to measure the infalling light from a lightbulb situated at the front of your ships 'motion' will find it to have no blue shift as you measure it at the aft. You will also find yourself weightless, following a geodesic. This effect and that you will find all experiments, at least all I can think up, giving you the same outcomes, no matter your 'speed' as measured by earth, or for that sake anywhere else, give all uniform speeds the same equivalence to me. They are all 'at rest' relative gravity, becoming inseparable from 'standing still' inside that room.

But we both expect a time dilation, don't we :)
And we both expect a Lorentz contraction.

There are no 'inertial frames' that won't have a 'gravitational acceleration', as long as we're discussing something made from matter. And in that way all three can be defined as being 'inertial frames'. Each one of them can define themselves, when doing a direct measurement on any of the other frames, as either moving with the other one being still, or anything in between, all the way up to themselves being the one not moving.

So where did that time dilation get 'created', relative what?

« Last Edit: 30/05/2011 21:59:08 by yor_on »

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #32 on: 30/05/2011 20:06:48 »
Yor_on,

There is insufficient information to answer the questions so I will cover the situations I think you are getting at. (I ignore gravity and concentrate on relative motion) ;-

1. The two alien space craft are moving together, in the same direction at the same speed and therefore have no relative motion between them. In this case, the Earth observer will see both space ship's clocks slowed down by the same amount due to their equal speed relative to the Earth. Both Alien observers will see NO time dilation from the other craft, but SR predicts they will see time dilation of Earth clocks to the same degree as the Earth observer sees for their clocks.
2. The two alien craft are both moving at the same speed as before, but now in opposite directions, passing one another. Now they will observe time dilation for each other's clock but greater than previously observed by the Earth observer due to their doubled relative speed. The Earth observer will see the same time dilation as previously for both craft.

I see exactly where the time dilation comes from in each case. It is the time dilation due to relative motion and is quantified by Lorentz.

Is there anything I haven't covered?

Actually, yes there is. I have neglected the Earth's time dilation due to its gravitational field and that will have an effect on all observations of objects higher up in the field. Locations higher up in space at the alien craft positions will have a faster clock than on Earth. So, if we start with the crafts having faster clocks due to their elevation and then slow them down due to their motion, we get the resulting time dilation (or quickening) for the craft as observed from Earth.
From the craft's frames, observing the Earth, and for both options above, they will first see the gravitational redshift (that's what we're talking about), then they will see the redshift or time dilation due to the relative motion added to this.
The observations between the craft remain unaffected by the Earth's time dilation field, unless they are at different elevations.

I think that covers it
« Last Edit: 30/05/2011 20:22:07 by Ken Hughes »

#### yor_on

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##### Is the speed of light the same to all observers?
« Reply #33 on: 30/05/2011 20:46:26 »
It's fun laboring with it, ain't it :)

And yes, you have about the same conclusions as me there. The point here being that we're discussing a 'uniform motion', inseparable from being at rest in a black box scenario. Now assume the two alien ships to have a different uniform 'speed' as defined by Earth. Then look at the time dilations. They will be differently defined for each one of them, relative each one of them it will differ too. The clocks though, as measured of the others ships-clock/earth etc will still be equivalently slow, not caring of whom is really 'moving'.

So, how do the universe keep count?
And, what defines motion?

#### yor_on

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##### Is the speed of light the same to all observers?
« Reply #34 on: 30/05/2011 21:16:53 »
The question can be stated as. Do the universe have a 'gold standard' of 'time'? If it has then all of those frames described can be expected to be 'time dilated' versus that standard. If it doesn't then all 'time dilations' will be arbitrarily defined. That mean that the only way you can discuss a 'time dilation' will be by a direct comparison, as in the twin experiment, or by watching those atomic clocks differ on the table relative the floor. The other point is that we actually seem to have a 'ground state' as shown in that there is no way to define any 'temporal change' in your own 'frame of reference' no matter if you're moving close to the speed of light in a vacuum. That is, ignoring really, really, hard radiation and tidal forces.

So, how do time and motion go together? The hard radiation will come through your 'relative motion' right :) And the different 'time dilations' you will have, simultaneously, as defined per what object you 'measure yourself' arriving to conclusions of different speeds will still be there. And lastly, that time you really have measured for living your life, by fate or (..insert word of choice :) doesn't really care about that motion, neither about that mass or energy. It is the same measure wherever you are.

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #35 on: 30/05/2011 22:28:15 »
It seems I am unable to post

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #36 on: 30/05/2011 22:28:33 »
At least, to post the message I wanted

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #37 on: 30/05/2011 22:28:45 »
Here goes again

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #38 on: 30/05/2011 22:31:12 »
Nope ! It's no use, it seems my message has been prevented from being posted. I don't know why.
Any suggestions?

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #39 on: 30/05/2011 22:33:31 »
I get an error message saying there were the following errors  but no list of errors

#### yor_on

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##### Is the speed of light the same to all observers?
« Reply #40 on: 30/05/2011 22:33:54 »
I don't know?

What was it, some words are 'black listed' I'm afraid?

#### yor_on

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##### Is the speed of light the same to all observers?
« Reply #41 on: 30/05/2011 22:35:37 »
And sometimes, depending on connection and location it do seems to 'hang'. At least as I've experienced? Try again after a reboot and see if it makes a difference.
==

Or possibly you tried to insert to many words for one post?
That can give a error too.
« Last Edit: 30/05/2011 22:37:11 by yor_on »

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #42 on: 30/05/2011 22:38:51 »
I'll try splitting the message

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #43 on: 30/05/2011 22:45:15 »
No good. I can't think I used any words which might be banned. I give up.

Anyway, I was making the same point as you regarding a "Universal Time Rate" which is the hypothetical time rate at a "stationary" position at infinite distance from all the mass in the universe. Yes I agree, all time dilation is from this time rate downwards

#### yor_on

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##### Is the speed of light the same to all observers?
« Reply #44 on: 30/05/2011 22:49:45 »
Yes :)

Then you and me suspect the same there. I haven't seen anyone defining it as a 'constant' yet but I think it is one myself. You might want to define SpaceTime as a whole 'system' interacting where 'entropy' becomes the 'time rate', but myself I don't like it :)

Just because of that fact you bring up there. that we do seem to have a same 'ground state'.
If we didn't no frames should be expected to 'fit' as I see it, coming together, but they do, always..

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #45 on: 30/05/2011 22:52:06 »
It is not by chance we have come down to discussion time as time is THE fundamental that explains some of the problems with current theory.

I have developed some definite ideas regarding time and its effects and will post these in the new theory topics soon.

#### yor_on

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##### Is the speed of light the same to all observers?
« Reply #46 on: 30/05/2011 22:56:12 »
Do that Ken. Time is a very interesting subject to me :)
And weird..

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #47 on: 30/05/2011 22:58:30 »
I'm not sure it is a simple constant. I see it perhaps as a constant for each "universe" or set of frames, infinite in number.

I don't see the link between time and entropy. There just different. Entropy is our way of looking at a particular property whilst time is a FUNDAMENTAL entity, however we may look at it.

#### yor_on

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##### Is the speed of light the same to all observers?
« Reply #48 on: 30/05/2011 23:00:50 »
I think it has to be the server, looking at the post count under our names it hasn't updated the count at all? You got '25' posts the whole page.

0uch..
==

Weird, it did update . Okay it does it globally for each post..

So something else then?
« Last Edit: 30/05/2011 23:02:26 by yor_on »

#### Ken Hughes

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##### Is the speed of light the same to all observers?
« Reply #49 on: 30/05/2011 23:01:01 »
Yor_on,

It's been great having this discussion with you today.

It is now midnight here in Spain so I shall now get to bed.

Goodnight and thanks

#### The Naked Scientists Forum

##### Is the speed of light the same to all observers?
« Reply #49 on: 30/05/2011 23:01:01 »