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In accordance with lounge rules "discussing anything in a software developer's life that takes your fancy except programming questions", here's a request for feedback on a time dilation example -
The movie Interstellar includes examples of time dilation.
My objective is to be able to provide a simple explanation and example of time dilation.
Is my link below a good time dilation example or does it require correction or more clarification?
http://www.oproot.com/a/nav/if/time-dilation.html[^]
To access via mobile device, go to oproot.com > experiments > time dilation example
Position and time were once thought to be absolute. Newton's laws of motion discredit absolute position in space. Einstein's theory of relativity discredits absolute time. The time dilation effect comes from the nature of spacetime.
Time and space are now seen as dynamic quantities with each individual particle, or planet, having its own unique measure of time depending on where and how each is moving.
- The Illustrated A Brief History of Time, Stephen Hawking, Page 45
In the example link, there are 4 observers with 4 synchronized clocks. 2 observers are on the surface of the earth. 1 observer is in space above the earth. 1 observer has returned from a high-speed space mission.
When regrouping the clocks are different -
Observer 1 surface clock is 12:25. (O1)
Observer 2 surface clock is 12:25. (O2)
Astronaut 1 clock is 12:28. (A1)
Astronaut 2 clock is 12:21. (A2)
Extra credit question -
Are there any science experiment ideas (on a budget) that can be performed to demonstrate time dilation?
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Thank you for the feedback and catching the axis/longitude error. I've updated the text. 
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The record holder in time travel by time travel time dilation, as far as I know, is still the Russian who was stuck on the space station Mir 25 years ago when the Soviet Union came to an end and they took their time to get him down. He gained something like half a second total.
The language is JavaScript. that of Mordor, which I will not utter here
This is Javascript. If you put big wheels and a racing stripe on a golf cart, it's still a f***ing golf cart.
"I don't know, extraterrestrial?"
"You mean like from space?"
"No, from Canada."
If software development were a circus, we would all be the clowns.
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What helped me understand time dilation, not that I 'understand' it, was the explanation of how the speed of light is constant within a reference point.
In order to maintain this constant speed of light, time dilation takes place. So for a person travelling in a car, at 50 mph, for their reference point the light coming out of the headlamps is not the speed of light +50mph but the speed of light(i.e. if they measured the speed of the light coming out of their headlamps) as their time dilates due to the 50mph speed their car is travelling at.
Now it gets more interesting when two cars are moving towards each other with a closing speed of 100mph - the light from the opposite car is still perceived as travelling at the speed of light and not the speed of light +50mph(the light speed measuring car's 50mph having been explained in the previous paragraph).
If someone can explain how time dilation works in this context that would be great 
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
modified 6-Jul-15 2:10am.
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- Each car is moving toward the other at 50 km/h relative to an observer on the ground.
- The relativistic addition of velocities gives a relative velocity for the two cars of slightly less than 100 km/h (first instance of time dilation).
- Light emitted at a given frequency carries its own clock with it, namely the frequency. Therefore when this "clock" is read in another frame of reference, it will exhibit both the classical Doppler effect and time dilation, together known as the relativistic Doppler effect (second instance of time dilation).
I hope this helps a bit.
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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Brilliant, thanks
I will read up more on this now, the light carrying its own clock with it helps.
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
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As far as I understood, space is bent stronger around a fast object (or a large mass, which is essentially the same due to E = mc^2). The light has to travel a longer distance through the curvature.
The language is JavaScript. that of Mordor, which I will not utter here
This is Javascript. If you put big wheels and a racing stripe on a golf cart, it's still a f***ing golf cart.
"I don't know, extraterrestrial?"
"You mean like from space?"
"No, from Canada."
If software development were a circus, we would all be the clowns.
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You are confusing gravitational lensing (an effect due to General Relativity) with time dilation (and effect due to Special Relativity).
The essential difference between Special and General Relativity is that Special Relativity ignores gravity and only gives a partial treatment of acceleration, while General Relativity assumes that as we cannot tell the difference between gravity and acceleration, they should be treated as equivalent. All manner of problems are solved (and created) by this assumption...
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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An experiment to demonstrate (prove) Relativity in the kitchen is stretching things a bit.
However real evidence of the predictions of Relativity (General and Special) is present in the global GPS system. The orbiting GPS clocks would gain about 38 microseconds relative to earth clocks causing about a 10km error every day. This is made up of a loss of 7 microsecs due to the speed of orbit and a gain of 45 microsecs due to the effect of gravity. This is accounted for by making the GPS clocks tick more slowly by 38 microsec a day done before they are launched.http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html[^]
Peter Wasser
"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell
modified 5-Jul-15 21:19pm.
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The Operator wrote: The movie Interstellar includes examples of time dilation
Bad examples. REALLY bad examples.
With regards to the water planet they said that they'd had 2 decades (or whatever) of data from the person who was meant to land, but when they arrived they all suddenly surmised that the previous astronaut had landed mere minutes before them.
ARGH!
Time still passed. Both parties left from the same place and arrived at the same place and travelled more or less through the same gravitational fields, so if they left 20 years apart they would arrive 20 years apart. It's just that their clocks wouldn't match the clocks back on earth (or a clock outside of the pull of the nearby blackhole)
/bangs head.
cheers
Chris Maunder
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I feel you would be better off concentrating on one effect at a time, and first discuss the effects of speed/acceleration, then maybe adding in gravity. Einstein once said (supposedly) 'moving clocks run slow' - this doesn't explain anything, but confirms what needs explaining.
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I'm sorry but...
The only thing I can say for sure about the movie "Interstellar" and time (dilated or otherwise) is that it was a complete waste of mine 
Sometimes, it just is, OK!
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I would recommend the book:
"Why Does E=mc2? (And Why Should We Care?)"
by Brian Cox, Jeff Forshaw.
[The authors are Scottish Physicists and if you get the audio book and listen to them rea it with their accents it's even better!]
They talk about experiments where radioactive particles were run in a particle accelerator and compared with particles of the same material not run. They could measure the half life and the difference between the two samples was exactly as Einstein's theory would predict.
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Scottish? Wow! People really are accent blind. I never believed it before!
Brian Cox hails from Oldham in Lancashire. I've not been able to find a birthplace for Jeff Forshaw but has a similar accent though whether this has been acquired from working at Manchester University I cannot say. However they are both very much English. Northern English but definitively not Scottish!
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Despite my confusion they are brilliant at explaining a very complex subject!
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Doesn't GPS (and perhaps most /all sattelites) take time dilation into account?
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I believe that this fits your requirements
I was going through my e-mails for some information on atomic frequency standards, when I came across an e-mail that I had sent to Tom Van Baak in 2007 congratulating him for his family-friendly time dilation experiment. If you are not familiar with his work, I heartily recommend that you explore his precision-time-keeping webpage at LeapSecond.com.
Tom wanted to demonstrate Relativity to his children, so in September 2005 he loaded the family’s minivan with portable power supplies, monitoring equipment, and three HP 5071 cesium clocks. With his three kids and some camping gear in tow, he drove the winding roads spiraling up Washington’s Mt. Rainier and checked the family into a lodge 5,319 feet above sea level.
By keeping the clocks at altitude for a weekend they were able to detect and measure the effects of relativistic time dilation compared to atomic clocks they left at home. The amazing thing is that the experiment worked! The predicted and measured effect was just over 20 nanoseconds.
For more information, go to Tom’s excellent webpage “Project GREAT: General Relativity Einstein/Essen Anniversary Test – Clocks, Kids, and General Relativity on Mt Rainier”
http://www.diyphysics.com/2012/03/15/tom-van-baaks-family-friendly-relativistic-time-dilation-experiment/
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The problem with the time dilation examples are the inaccuracies in it make almost everything unknown. Where is the orbit relative to Earth? Once you get far enough out, the orbit with earth will lose to the orbit around the sun. How long does it take to get a three minute change in time? What's the mechanism for tracking time? If it is a grandfather clock movement, it will take 3 minutes in orbit to get a 3 minute time difference. If it is atomic resonance, I'd guess (WAG) it would take 3 million days to get 3 minutes difference in synchronous orbit. Being able to accelerate infinitely while reaching 99.9999999999% of the speed of light it would take 1.5 minutes out, reverse direction and 1.5 minutes back to get a 3 minute difference and it would have to have an incredibly strong machine to withstand the G forces and very fast computing to be able to tell when you are 1.5 light minutes away to stop and come back. If you went with it, you would be gelatinous goo when you get back. IE The web site doesn't do any real explaining of what is happening to cause the dilation or how long it takes to see that dilation.
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Quote: Being able to accelerate infinitely while reaching 99.9999999999% of the speed of light
Er ... this and other self-contradictory statements suggest that you really haven't got to grips with this at all. Sorry!
Quote: it make almost everything unknown
But are they known unknowns or unknown unknowns?
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I'm contradictory? I intentionally made it that way because of the web link that synchronized two clocks and kept one on earth and installed the other one on a ship going nearly the speed of light. The web site certainly didn't explain how gravity or speed affects time. I believe gravity affects it because space around a heavy body is bent changing the speed light moves through space near a heavy body and that somehow affects time. I certainly don't know enough about it to properly explain how it all works, but I know enough to recognize when I see a poorly made example that doesn't really explain anything.
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You are really off base.
This can be measured and has been. It's real.
You are making the mistake of trying to relate relativity physics to your personal experience and common sense. Doesn't work.
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Quantum physics seems full of self-contradictory statements. That's why I self-contradicted myself. The examples always have spaceships going near the speed of light without ever explaining how you got the ship moving that fast. Nor do they use the math needed because the ship is already moving that fast when you start measuring the time effects.
Of course they have proof they are right. The great wizard of OZ knows all, just ignore the man you see behind the curtain.
The theory of relativity was and still is a theory. Even though the light shifting effects of binary stars can be seen and measured as their orbital positions shift relative to us, we aren't seeing anything in space moving near the speed of light to us.
The speed of light is about 300000000 m/s, Earth gravity is about 9.75 m/s^2. The time to reach the speed of light in "normal" physics accelerating at "Earth gravity" would approximately be 300000000/(9.75*3600*24) or about 356 days. You being in the space ship using quantum physics, the perceived time becomes less than the actual time so you need to slow the acceleration down to match perceived time. (You would start at a force of 2 Gs so the initial acceleration is 1 G away from earth and cut down on the force as you reach escape velocity.) This also ignores how your propelent can work since it is almost stationary as you near light speed.
There isn't any way to reach the speed of light using quantum physics because as you near the speed of light, the power needed increases exponentially to maintain the perceived 1G acceleration until the power doesn't exist.
I don't know the math to calculate it, but if you perceive one object from earth moving at 0.6 times the speed of light (SOL) in one direction and another moving at 0.6 SOL in the opposite direction, it appears like they are approaching at 1.2 times the SOL while each object sees the other object is moving at less than SOL towards them. (These "ships" should have view screens with stickers saying "objects you see are moving faster than they appear to be moving")
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