Back to Home

God & Science Forum Message

Forums: Atm · Astrophotography · Blackholes · Blackholes2 · CCD · Celestron · Domes · Education
Eyepieces · Meade · Misc. · God and Science · SETI · Software · UFO · XEphem
RSS Button

Home | Discussion Forums | God and Science | Post

Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...
The Space and Astronomy Agora
The Physics Of A Subway Ride

Forum List | Follow Ups | Post Message | Back to Thread Topics
Posted by Aurino Souza on November 28, 2003 14:46:38 UTC

I wondered about this on the subway a few days ago:

A train is stopped at the station. Its position is well-determined and its velocity is zero. You check your wristwatch. At some point you realize the train is moving. Then you wonder: at what time did the train start moving? What was the time in your watch when the train went from "stopped" to "moving"?

This is a very interesting question (and somehow related to the "infinity" thing in a post below). The problem is, there is no point in time in which the train's velocity changes from zero to non-zero. At time t, v = 0; at time t', v > 0; there is absolutely no time between t and t'. Time is granular/quantum/not-infinitely-divisible by definition!

Three issues immediately come to my mind:

- Why do we consider time to be continuous when define it otherwise?
- How do we calculate the "minimum time" (t' - t)?
- When you think about the two issues above, you realize something amazing. But you have to see that for yourself.

Have fun

Follow Ups:

Login to Post
Additional Information
About Astronomy Net | Advertise on Astronomy Net | Contact & Comments | Privacy Policy
Unless otherwise specified, web site content Copyright 1994-2024 John Huggins All Rights Reserved
Forum posts are Copyright their authors as specified in the heading above the post.
"dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET"
are trademarks of John Huggins