Physics Help Forum Question about Time

 Special and General Relativity Special and General Relativity Physics Help Forum

 Dec 20th 2016, 11:31 AM #1 Junior Member   Join Date: Dec 2016 Posts: 2 Question about Time I’m writing a philosophy paper and need a little help with some maths on Time. To use the example within the documentary “The Illusion of Time” (Example Link: https://www.youtube.com/watch?v=YRwZ55zjzxc - Example illustrated From: 24:15min – 26:50min in the vid). The presenter explains how if we are standing at Point “A” (lets say us on earth), and an Alien is standing at Point “B” 10 billion light years away from us, that if the alien gets on a bike and starts riding away or towards us at a speed then the Aliens perception of “NOW” time would change possibly as drastic as being 200 years in the future or past, depending on the direction the Alien was to ride. My question is, while I’m sure there isn’t a simple equation… is there possibly a simple equation that can help explain this effect? Possibly an equation that shows, if the distance between point A and point B is “X” distance, and the Alien at point B moves directly further away (being a positive speed), or closer towards (being a negative speed), over a total distance of “Y” then when the Alien stops moving how much would it’s “now” time have change (in terms of seconds) compared to the person who stayed still at Point A. I'm no physicist but I'd really like to find a simple way of explaining this phenomenon and showing it's working through numbers to use within my paper about Time and our perceptions of it. If anyone out there can help that would be amazing!!!! Many thanks, - Anthony
 Dec 20th 2016, 11:42 AM #2 Senior Member   Join Date: Aug 2010 Posts: 232 Accidental double post. Last edited by HallsofIvy; Dec 22nd 2016 at 07:09 AM.
 Dec 20th 2016, 11:46 AM #3 Senior Member   Join Date: Aug 2010 Posts: 232 I think you are referring to the "Lorentz transformation": If A is moving at speed v relative to B then A measures time elapsing at a rate equal to $\displaystyle \frac{1}{\sqrt{1- \frac{v^2}{c^2}}}$$\displaystyle \left(t- \frac{vx}{c^2}\right)$ where t is the rate at which B measures time elapsing.
 Dec 20th 2016, 01:12 PM #4 Junior Member   Join Date: Dec 2016 Posts: 2 Thanks for that - I think we're on the right track ... with the Lorentz transformation, for my limited understanding in its basic formula it more so shows what B's perception of time would be when in a similar space or when visualizing a similar space as A, but while B is traveling at a different speed to A. Any ideas how i might account for a different distance between them? In the documentary they show how over a large distance a very small speed can change the perception of time quite greatly. I guess I'm still having trouble figuring out how to calculate that side of things. Thanks for the help so far
 Dec 21st 2016, 10:04 AM #5 Senior Member   Join Date: Jun 2010 Location: NC Posts: 361 Non-relativistic Time Hi, There are some other aspects of time. 1.21 Events and Time | THERMO Spoken Here! Perhaps this will be of value. JP

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