# a Relativity question **URL:** \ **Category:** Factual Questions\ **Created:** [January 31, 2000, 9:13pm UTC](https://boards.straightdope.com/t/a-relativity-question/6948 "2000-01-31T21:13:00Z")\ **Posts on this page:** 2\ **Page:** 3
**Author:** ![JonF](https://avatars.discourse-cdn.com/v4/letter/j/cab0a1/32.png) [@JonF](https://boards.straightdope.com/u/JonF)\ **Post date:** [February 9, 2000, 2:04pm UTC](https://boards.straightdope.com/t/a-relativity-question/6948/41 "2000-02-09T14:04:00Z")
> [@](#): > > but you can tell if you are accelerating or not Sorry, no, you can’t. We’re approaching the limts of my memory, but you can’t tell the difference between acceleration and a gravitational “field”. This “equivalence principle” is **the** foundation of general relativity. See [The Equivalence Principle](http://members.aol.com/DrPhysics/equiv.html) and [Remarks on General Relativity](http://www.phys.virginia.edu/classes/252/general_relativity.html). * * * jrf ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [February 9, 2000, 4:24pm UTC](https://boards.straightdope.com/t/a-relativity-question/6948/42 "2000-02-09T16:24:00Z")
> [@](#): > > Sorry, no, you can’t. We’re approaching the limts of my memory, but you can’t tell the difference between acceleration and a gravitational “field”. :sigh: I knew someone would complain about this, I just knew it. I was trying to keep the lingo down. Try this instead: you _can_ tell if you are in an inertial frame of reference or not. ## At any rate, I was primarily aiming my remarks at a hypothetical universe where SR holds, and where there is **no gravity due to mass (sorry, the energy-momentum tensor)**. If you are in an SR universe, there is no reason for inertial frames of reference _not_ to be priveleged. _It is too clear, and so it is hard to see._ [Previous page](https://boards.straightdope.com/t/a-relativity-question/6948.md?page=2)