The Speed of Light

[Grandliseur]

just occurred to me....

if you gain the speed of light...... hold to it for a while.....
your return to the starting point would be everyone else's future
(everyone you left behind would continue forward)

and you would be the past

At the speed of light, a person wouldn't age. Those left behind would. Thus, any large increase e.g. 50% of light speed, would also affect your aging relative to others on earth. Thus they would seem to be aging more quickly while you would seem to be aging slower. Of course, this is because time moves at a different rate, and not because your longevity is increased.

 

[Polymath257]

Well, I once heard Professor Michio Kaku speak on time travel. Without wanting to be disrespectful - I thought it a lot of baloney. I do not believe time travel to be possible. (except forward by approaching the speed of light, thus reducing the rate you age relative to those who do not move this way)

If you should want to engage in this subject, let me know. It is not that my claim is that long btw.

Well, I'll leave off my views of Kaku. Let's just say that most physicists agree that time travel is hokum (outside of the fact that we go through time at the rate of 60 seconds every minute and relativistic time dilation). But talking about it gets a certain amount of attention.

 

[Polymath257]

At the speed of light, a person wouldn't age. Those left behind would. Thus, any large increase e.g. 50% of light speed, would also affect your aging relative to others on earth. Thus they would seem to be aging more quickly while you would seem to be aging slower. Of course, this is because time moves at a different rate, and not because your longevity is increased.

This is not quite accurate.

Again, all motion is relative. It makes no sense to simply say you are moving at 50% of the speed of light. It *only* makes sense to say you are moving at 50% of the speed of light in some reference frame. But, if this happens, that reference frame is *also* moving at 50% of the speed of light in *your* reference frame. There is a symmetry.

So, if you are moving at 50% of the speed of light past the Earth (i.e, in the reference frame of the Earth), then the Earth is moving at 50% of the speed of light in *your* reference frame. So, to people on Earth, you look like you are moving slower because of time dilation. But, symmetrically, if you look at the people on Earth, *they* look to *you* like they are moving slower. Both sides see the same time dilation in the other.

So both sides see the other as aging slower.

This is the 'twin paradox': how can both sides consistently see the other as moving slower? What happens if you go at 99.99% of the speed of light (with respect to the Earth), turn around and come back home? Who has aged less and why?

Well, the answer is that whichever one feels the acceleration (change of velocity) will age less. Since you are the one that needs to turn around, the rockets firing will make *you* feel the acceleration while those on the Earth do NOT feel the same. So you will age less. But the difference is due to the acceleration and NOT the speed alone.

 

[Thief]

At the speed of light, a person wouldn't age. Those left behind would. Thus, any large increase e.g. 50% of light speed, would also affect your aging relative to others on earth. Thus they would seem to be aging more quickly while you would seem to be aging slower. Of course, this is because time moves at a different rate, and not because your longevity is increased.

and you would return to your loved ones......as they knew you in the past
you would be.....the past

of course there is that assumption......your immediate condition would not accelerate

 

[Grandliseur]

Let's just say that most physicists agree that time travel is hokum

Thank you. That is my undiluted opinion.

But talking about it gets a certain amount of attention.

That what it is about, it seems.

It is totally irrational to me. Still, it may at times be used for not-so-bad fictional novels.

 

[Grandliseur]

Post ref: 63

It *only* makes sense to say you are moving at 50% of the speed of light in some reference frame.

This one makes sense. I have used the logic of the 'reference frame' before.

So both sides see the other as aging slower.

That is news to me. It is also somewhat hard to understand.

What happens if you go at 99.99% of the speed of light (with respect to the Earth), turn around and come back home? Who has aged less and why?

Well, the answer is that whichever one feels the acceleration (change of velocity) will age less. Since you are the one that needs to turn around, the rockets firing will make *you* feel the acceleration while those on the Earth do NOT feel the same. So you will age less. But the difference is due to the acceleration and NOT the speed alone.

Is it possible to verify this?
We do see the satellites in time experiments, perhaps due to gravitational difference, experiences time slight different from ours, i.e. their clocks run a tiny bit slower. That doesn't seem to be dependent on acceleration, though gravity perhaps functions as acceleration does in this case.

 

[Grandliseur]

and you would return to your loved ones......as they knew you in the past
you would be.....the past

of course there is that assumption......your immediate condition would not accelerate

I think I am going to quote your own material:
"
First you are told.... 'this is this...and that is that'.
Then someone else will come along and say...'No it ain't'.
"
Better quit while being ahead, right.

 

[Polymath257]

Post ref: 63

This one makes sense. I have used the logic of the 'reference frame' before.

That is news to me. It is also somewhat hard to understand.

Is it possible to verify this?
We do see the satellites in time experiments, perhaps due to gravitational difference, experiences time slight different from ours, i.e. their clocks run a tiny bit slower. That doesn't seem to be dependent on acceleration, though gravity perhaps functions as acceleration does in this case.

Yes, that is the case here.

And yes, this can be verified. Essentially every particle accelerator has to deal with these relativistic effects. If you have muons going close to the speed of light, they don't decay as quickly. The effect has been verified even with airplanes going at typical speeds.

 

[Grandliseur]

Yes, that is the case here.

And yes, this can be verified. Essentially every particle accelerator has to deal with these relativistic effects. If you have muons going close to the speed of light, they don't decay as quickly. The effect has been verified even with airplanes going at typical speeds.

Having fun!
I have read too much SF. When they travel at speed of light in the stories, or close to it, they are the only ones not aging. This relative aging - ruins it all.

 

[Grandliseur]

You know what I find so incredible, besides everything you wrote making sense, the ideas you put forth are so far from the mind of the average human being that they would think you are crazy.

I just found something about space-time you might like.

In paragraph, or subsection, #6 of the article, it speaks about some of what we discussed.
https://www.forbes.com/sites/starts...hat-quantum-gravity-could-solve/#5c19faf62ba3

 

[Thief]

I think I am going to quote your own material:
"
First you are told.... 'this is this...and that is that'.
Then someone else will come along and say...'No it ain't'.
"
Better quit while being ahead, right.

and who would be ahead?

the guy that can travel at the speed of light.....and assuming he won't age (if at all)
or the people left behind......moving into the future

to avoid dying.....you can't shut down your movment

 

[Grandliseur]

and who would be ahead?

the guy that can travel at the speed of light.....and assuming he won't age (if at all)
or the people left behind......moving into the future

to avoid dying.....you can't shut down your movment

There is rarely a win win situation. It usually comes down to in the end - loose loose.
Hope the end comes with a donut and coffee, and sweet dreams.

 

[james dixon]

If my understanding is correct, the maximum speed of light is independent of physical motion or frames of reference, therefore the velocity of the train would have nothing to do with it. There is the velocity of the train, and the velocity of light, separately. Did I get that right?

What you are saying is correct as I see it but the speed of light is known. And it is not the speed of light that is the issue, it is the increased speed of the bullet that was fired from the train. The velocity of the bullet did increase from its normal velocity to the velocity of the train plus (+) the velocity of the bullet.

 

[Polymath257]

What you are saying is correct as I see it but the speed of light is known. And it is not the speed of light that is the issue, it is the increased speed of the bullet that was fired from the train. The velocity of the bullet did increase from its normal velocity to the velocity of the train plus (+) the velocity of the bullet.

Suppose you were on a train going at 50% of the speed of light past someone and fired a super-high speed bullet that, from your perspective goes at 70% of the speed of light in your direction of travel (so, intuitively the speeds would add up). The person you are going past will NOT see the bullet going at 50%+70%=120% of the speed of light. The reason? There are time dilation and length contraction effects.

What the person on the ground *would* see is your bullet going at (.5 +.7)/(1+ .5*.7) =1.2/1.35 =.8889 =88.89% of the speed of light.

The general formula is (v1+v2)/(1+v1*v2) where v1 and v2 are the fractions of the speed of light. If v2 goes in the other direction, just change the +'s to -'s.

So, if you shot your bullet *backwards*, the person you are going past would see it going (.5-.7)/(1-.5*.7)=-.2/.65 =-.3077=30.77% of the speed of light in the direction opposite of you.

 

[james dixon]

So, if you shot your bullet *backwards*, the person you are going past would see it going (.5-.7)/(1-.5*.7)=-.2/.65 =-.3077=30.77% of the speed of light in the direction opposite of you.

That is a very interesting point of view. It will take me some time to wrap my head around it.

Thanks for the post -

 

[Milton Platt]

I read up on relativity today, and am wondering if there is extra theory behind why the speed of light in a vacuum is 299,792,458 m/s and not some other value? Or is this simply a measured phenomena with no further explanation right now? Thanks!

It would be a good idea to ask a physicist, no?

 

[sayak83]

That is a very interesting point of view. It will take me some time to wrap my head around it.

Thanks for the post -

It's not a point of view FYI. These effects have been directly observed by physics. It happens at all velocities, but at slow speeds, the corrections are too small to be noticed without a high precision instrument.

 

[james dixon]

You are missing the point or,.,. I am not explaining it properly; I am not sure which, at this moment.

Set aside the speed of light. This is irrelevant to this discussion.

Now using my analogy; tell me whether that bullet increased from its stated speed potential to a greater speed.

Check the appropriate box below:
[ ] no
[ ] yes

-

 

[Polymath257]

You are missing the point or,.,. I am not explaining it properly; I am not sure which, at this moment.

Set aside the speed of light. This is irrelevant to this discussion.

Now using my analogy; tell me whether that bullet increased from its stated speed potential to a greater speed.

Check the appropriate box below:
[ ] no
[ ] yes

-

With respect to whom?

With respect to the gun that fired the bullet? no. still 70% of the speed of light.

With respect to the person for whom the gun is going past? yes. Now it is going at 88.89% of the speed of light.

ALL speeds are relative.

 

[Thief]

With respect to whom?

With respect to the gun that fired the bullet? no. still 70% of the speed of light.

With respect to the person for whom the gun is going past? yes. Now it is going at 88.89% of the speed of light.

ALL speeds are relative.

all motion is relative

an object moving with you alongside will appear to be motionless
you need that third point