Quantcast
  • Register
PhysicsOverflow is a next-generation academic platform for physicists and astronomers, including a community peer review system and a postgraduate-level discussion forum analogous to MathOverflow.

Welcome to PhysicsOverflow! PhysicsOverflow is an open platform for community peer review and graduate-level Physics discussion.

Please help promote PhysicsOverflow ads elsewhere if you like it.

News

PO is now at the Physics Department of Bielefeld University!

New printer friendly PO pages!

Migration to Bielefeld University was successful!

Please vote for this year's PhysicsOverflow ads!

Please do help out in categorising submissions. Submit a paper to PhysicsOverflow!

... see more

Tools for paper authors

Submit paper
Claim Paper Authorship

Tools for SE users

Search User
Reclaim SE Account
Request Account Merger
Nativise imported posts
Claim post (deleted users)
Import SE post

Users whose questions have been imported from Physics Stack Exchange, Theoretical Physics Stack Exchange, or any other Stack Exchange site are kindly requested to reclaim their account and not to register as a new user.

Public \(\beta\) tools

Report a bug with a feature
Request a new functionality
404 page design
Send feedback

Attributions

(propose a free ad)

Site Statistics

205 submissions , 163 unreviewed
5,047 questions , 2,200 unanswered
5,345 answers , 22,709 comments
1,470 users with positive rep
816 active unimported users
More ...

  Does an apple "falling" from a tree move only in the time direction in curved spacetime?

+ 0 like - 0 dislike
800 views

Does it appear to a distant observer that the distance between the earth and the apple is decreasing as they move along their geodesics but only in the time direction , and in reality neither the earth or the apple move through space?

Closed as per community consensus as the post is not graduate-level
asked Nov 25, 2018 in Closed Questions by anonymous [ no revision ]
recategorized Nov 27, 2018 by Dilaton

not graduate+ level. Users with 500+ reputation may vote here to close. 

PhysicsOverflow is a site for advanced physics. Please ask elementary 
question in other online platforms that value such questions. 

I bet you can't answer it correctly..

Your statement reveals elementary problems in understanding the notions involved. Motion ''in time only'' depends on the coordinate system used, and would imply in this coordinate system that the spatial distance does not change, which is obviously wrong.

1 Answer

+ 0 like - 0 dislike

In GR "moving through space" is implied; otherwise the notion of space would be useless. You mistake a "free motion" in space (=along geodesics) for "no motion at all".

answered Nov 27, 2018 by Vladimir Kalitvianski (102 points) [ no revision ]




user contributions licensed under cc by-sa 3.0 with attribution required

Your rights
...