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Author Topic:   The Twins Paradox and the speed of light
RickJB
Member (Idle past 4990 days)
Posts: 917
From: London, UK
Joined: 04-14-2006


Message 61 of 230 (480508)
09-04-2008 6:43 AM
Reply to: Message 60 by cavediver
09-04-2008 6:36 AM


Re: Calculation
Units aside, that great news - it means that I understand the (very) basic concept!
I've always been visual thinker when it comes to maths, so graphs help me alot.

This message is a reply to:
 Message 60 by cavediver, posted 09-04-2008 6:36 AM cavediver has not replied

  
V-Bird
Member (Idle past 5584 days)
Posts: 211
From: Great Britain
Joined: 03-22-2004


Message 62 of 230 (480509)
09-04-2008 7:17 AM
Reply to: Message 57 by cavediver
09-03-2008 6:27 PM


Re: Calculation
It is often overlooked that some points or packets of energy will travel in time alone [along with us], for example the four forces attempt to be entirely time based, their 'energy' is occasionally hidden that way, we often see this energy in quantum fields, that 'appear' to have no motion, they have but none in the first three dimensions, it is part of how FTL gravitational exchange makes itself present in our SoL world.
In QFT, the replacement of 'virtual particles' with either particles that are time alone based or FTL phenomena produces further answers and yet does not disturb the theory or the results that have come from it.
In fact to date I know of not a single 'virtual photon' or similar account of action or actions that cannot be adequately or more correctly attributed to the two instances above.

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RickJB
Member (Idle past 4990 days)
Posts: 917
From: London, UK
Joined: 04-14-2006


Message 63 of 230 (480519)
09-04-2008 8:20 AM
Reply to: Message 60 by cavediver
09-04-2008 6:36 AM


Re: Calculation
Better?
Edited by Admin, : Reduce image width.

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boysherpa
Junior Member (Idle past 5371 days)
Posts: 19
From: Lomita, CA
Joined: 10-04-2008


Message 64 of 230 (485044)
10-04-2008 3:42 PM


why is this a paradox?
I have considered this and other so-called time paradox issues for many years. My major complaint with our view of time paradoxes is that we cannot test most of them. We really create these time paradoxes ourselves.
Not this issue - the twins "paradox". This has been, in a number of ways, verified. The GPS navigation system, for example, must account for this every nanosecond in order for you to have accurate clock and location data delivered to your navi-guesser (both high velocity and lower gravity influence the clock on the satellite relative to the NIST standard clocks). But, it is unclear what is really happening in terms of some separate concept called time.
It is clear that relative "time" between the observer on the ground and the satellite is what we are talking about (hence the term relativity). There are two questions, however. 1) What are the relative clock speeds, and 2) What _time_ is experienced by each clock. Note that these are not just semantic differences. Also note that the first is more related to the question of which twin has aged more, if you think of the body as a machine with only so many telomeric ticks in it.
So, a cool concept, which I encountered in a sci-fi novel, is the idea of living forever by being accelerated to near light speed. Is this a paradox? Can it actually occur? (setting aside the practical issues debate)
It is clear to me that time is not a "dimension". Time is what clocks measure, but perhaps time does not exist outside of the context of clocks. This seems to be a huge topic for discussion.
Edited by boysherpa, : typo

Replies to this message:
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New Cat's Eye
Inactive Member


Message 65 of 230 (485134)
10-05-2008 12:45 PM
Reply to: Message 64 by boysherpa
10-04-2008 3:42 PM


Re: why is this a paradox?
It is clear to me that time is not a "dimension". Time is what clocks measure, but perhaps time does not exist outside of the context of clocks.
Did you read through this thread?
There's some great explanations on how time really is a dimension and it is not just a result of clocks measuring.
1) What are the relative clock speeds, and 2) What _time_ is experienced by each clock.
Maybe this post will help. Its #24 in this thread.

Science fails to recognize the single most potent element of human existence.
Letting the reigns go to the unfolding is faith, faith, faith, faith.
Science has failed our world.
Science has failed our Mother Earth.
-System of a Down, "Science"
He who makes a beast out of himself, gets rid of the pain of being a man.
-Avenged Sevenfold, "Bat Country"

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New Cat's Eye
Inactive Member


Message 66 of 230 (485135)
10-05-2008 12:49 PM
Reply to: Message 50 by onifre
07-07-2008 2:22 PM


Re: Here is the simple explanation....maybe
The time dilation would only exist if the clock for measuring time is at the observers end. The clock in the twins shuttle will not have slown down.
Slown...
Then why aren't the twins the same age?

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Replies to this message:
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onifre
Member (Idle past 2950 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 67 of 230 (485138)
10-05-2008 1:57 PM
Reply to: Message 66 by New Cat's Eye
10-05-2008 12:49 PM


Re: Here is the simple explanation....maybe
Slown...
Slowed...sorry about that. LOL, sometimes I throw shitty english out when I type quickly. Im the by-product of a text messaging world where spelling is optional.
Then why aren't the twins the same age?
What im explaining is that if you have a watch, and I have a watch, and they are synchronized, and you are traveling away form me in a rocket, in both frames of reference the watches are ticking normally. That is Einsteins elevator experiment,
Einstein's Relativity
The twins paradox deals with distance being reduced when traveling through space...as per Son Goku's equation. The stationary twin is traveling through more space, and time. The twin that is moving is traveling through less space, and time. So the stationary twin, having traveled more time is older than the twin who traveled for less time.
Edited by onifre, : No reason given.

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Replies to this message:
 Message 68 by New Cat's Eye, posted 10-06-2008 10:03 AM onifre has replied

  
New Cat's Eye
Inactive Member


Message 68 of 230 (485202)
10-06-2008 10:03 AM
Reply to: Message 67 by onifre
10-05-2008 1:57 PM


Re: Here is the simple explanation....maybe
The stationary twin is traveling through more space, and time. The twin that is moving is traveling through less space, and time.
Wait... isn't it that:
The stationary twin is traveling through more less space so therefore more time and the moving twin is traveling through less more space so therefore less time.
Then we'd reach the same conclusion:
quote:
So the stationary twin, having traveled more time is older than the twin who traveled for less time.
because then, it make perfect sense to me

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Replies to this message:
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onifre
Member (Idle past 2950 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 69 of 230 (485222)
10-06-2008 12:35 PM
Reply to: Message 68 by New Cat's Eye
10-06-2008 10:03 AM


Re: Here is the simple explanation....maybe
The stationary twin is traveling through more less space so therefore more time and the moving twin is traveling through less more space so therefore less time.
Here's Son Goku's equation of the paradox'
Son Goku writes:
Stationary twin:
If one twin sits where they are for four seconds they end up with coordinates:
(1,200,000,000 ; 0) or t=1,200,000,000 and x=0.
Now I'll compute the spacetime distance. Since dx=0 (no difference or change in spatial coordinate) we just have ds^2 = dt^2.
dt = 1,200,000,000 - 0 = 1,200,000,000
dt^2 = 1,440,000,000,000,000,000
Hence ds^2 = 1,440,000,000,000,000,000 and taking the square root:
ds = 1,200,000,000 meters.
Moving twin:
The moon is roughly 384,000,000 meters from Earth. The second twin starts at Earth and travels to the moon in two seconds.
So they start at (0 ; 0) and end up at (600,000,000 ; 384,000,000).
The spatial difference is dx = 384,000,000 - 0 = 384,000,000
Similarly, dt = 600,000,000.
dx^2 = 147,456,000,000,000,000
dt^2 = 360,000,000,000,000,000
ds^2 = 360,000,000,000,000,000 - 147,456,000,000,000,000 = 212,544,000,000,000,000.
Taking the square root, ds = 461,024,945 meters.
Assuming the twin takes an exactly similar journey back to Earth, that is they return in two seconds, then the distance for the return journey is again ds = 461,024,945 meters.
Hence the total spacetime distance of the moving twin is
ds = 2 x 461,024,945 meters = 922,049,890 meters.
Which is significantly less than the 1,200,000,000 meters of the stationary twin. Hence spacetime distance is reduced by moving through space.
Which still gives us the end result of,
quote:
So the stationary twin, having traveled more time is older than the twin who traveled for less time.
CS writes:
because then, it make perfect sense to me
That's all I ever aim to do.

"All great truths begin as blasphemies"
"I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth."--Bill Hicks
"I never knew there was another option other than to question everything"--Noam Chomsky

This message is a reply to:
 Message 68 by New Cat's Eye, posted 10-06-2008 10:03 AM New Cat's Eye has replied

Replies to this message:
 Message 70 by New Cat's Eye, posted 10-06-2008 1:14 PM onifre has replied
 Message 71 by cavediver, posted 10-06-2008 1:43 PM onifre has replied

  
New Cat's Eye
Inactive Member


Message 70 of 230 (485227)
10-06-2008 1:14 PM
Reply to: Message 69 by onifre
10-06-2008 12:35 PM


Re: Here is the simple explanation....maybe
When you wrote:
quote:
The stationary twin is traveling through more space, and time. The twin that is moving is traveling through less space, and time.
I read that as:
"The stationary twin is traveling through more space and is traveling through more time."
Which I thought was counter to the discussion about this:
Where traveling through more space results in traveling through less time (but that was about speed).
Son Goku's equations yield a smaller distance in spacetime, which is what you were referring too so I got confused.
Anyway, I think its cleared up for me now.
CS writes:
because then, it make perfect sense to me
That's all I ever aim to do.
That very honorable. I do too, but that's not all
sometimes its just too much fun to rile up the liberals

This message is a reply to:
 Message 69 by onifre, posted 10-06-2008 12:35 PM onifre has replied

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 71 of 230 (485230)
10-06-2008 1:43 PM
Reply to: Message 69 by onifre
10-06-2008 12:35 PM


Re: Here is the simple explanation....maybe
Just remember that although SG is measuring the spacetime distance (we usually use the term interval as it is less confusing, applying equally well to space and time) in metres, he could just as well have measured it in seconds, and the for us beings with mass, spacetime distance is actually time experienced. We have three concepts here: coordinate space, coordinate time, and spacetime interval. The static twin moves through less (no) coordinate space, than the travelling twin. Both move the same amount of coordinate time (from *sometime then* to *sometime later*), and the traveller's spacetime path (the time he experiences) is shorter than the static twin's spacetime path. Clear as mud

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Replies to this message:
 Message 72 by onifre, posted 10-06-2008 5:47 PM cavediver has replied
 Message 76 by MasFina, posted 10-07-2008 11:00 AM cavediver has replied

  
onifre
Member (Idle past 2950 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 72 of 230 (485272)
10-06-2008 5:47 PM
Reply to: Message 71 by cavediver
10-06-2008 1:43 PM


Re: Here is the simple explanation....maybe
Cavediver writes:
and the traveller's spacetime path (the time he experiences) is shorter than the static twin's spacetime path.
So it's in the spacetime interval that the experienced time is shorter. Is this only the case at speeds close to the SoL?

This message is a reply to:
 Message 71 by cavediver, posted 10-06-2008 1:43 PM cavediver has replied

Replies to this message:
 Message 73 by cavediver, posted 10-06-2008 6:27 PM onifre has replied

  
cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 73 of 230 (485277)
10-06-2008 6:27 PM
Reply to: Message 72 by onifre
10-06-2008 5:47 PM


Re: Here is the simple explanation....maybe
The spacetime interval IS the experienced time - they are one and the same. And it will be shorter for all speeds - just reasonably measurable as the difference in speed approaches c.

This message is a reply to:
 Message 72 by onifre, posted 10-06-2008 5:47 PM onifre has replied

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onifre
Member (Idle past 2950 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 74 of 230 (485280)
10-06-2008 6:38 PM
Reply to: Message 73 by cavediver
10-06-2008 6:27 PM


Re: Here is the simple explanation....maybe
The spacetime interval IS the experienced time - they are one and the same.
Right, I fudged up the way I tried to say it. Got it now.
And it will be shorter for all speeds - just reasonably measurable as the difference in speed approaches c.
Thanks again for the explanations cavediver.

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onifre
Member (Idle past 2950 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 75 of 230 (485293)
10-06-2008 11:41 PM
Reply to: Message 70 by New Cat's Eye
10-06-2008 1:14 PM


Re: Here is the simple explanation....maybe
CS writes:
That very honorable. I do too, but that's not all
sometimes its just too much fun to rile up the liberals
Yeah, but really, it fun to rile up anyone who's too far to either side.

This message is a reply to:
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