Testing Equivalence Principle: Prying Gravity From Inertia

[Celeritas02]

Hi,

So I came across this article on the internet, and it was about the Equivalence Principle. So I were interested and read it all, and in the article it said that the EP might be only approximately true. What interested me more about the article was it said that any theory of quantum gravity must violate the equivalence principle at some level. Before reading this article I always thought that the EP was established physics, I mean I thought it was experimentally proven...

I'm just a layman who is greatly interested in development in theoretical physics, so I'd be grateful if you could try to reply in less technical terms. Also forgive me for my poor English, I tried to do my best :)

Here's the link to the articles I read:
1. http://www.forbes.com/sites/johnfar...s-seek-a-divorce-prying-gravity-from-inertia/
2. http://www.wildcat.arizona.edu/arti...lenges-einsteins-theory-of-general-relativity

 

[PeterDonis]

I thought it was experimentally proven...

The equivalence of inertial and gravitational mass has been experimentally verified to 1 part in 100 billion:

http://en.wikipedia.org/wiki/Eötvös_experiment

(See under "Related Studies", the experiment run by Roll, Krotkov, and Dicke.)

1. http://www.forbes.com/sites/johnfar...s-seek-a-divorce-prying-gravity-from-inertia/
2. http://www.wildcat.arizona.edu/arti...lenges-einsteins-theory-of-general-relativity

Unfortunately, neither of these articles links to an actual scientific paper, so it's hard to say much that's useful. Pop science articles are not good sources if you actually want to understand the science.

 

[Celeritas02]

The equivalence of inertial and gravitational mass has been experimentally verified to 1 part in 100 billion:

http://en.wikipedia.org/wiki/Eötvös_experiment

(See under "Related Studies", the experiment run by Roll, Krotkov, and Dicke.)
Unfortunately, neither of these articles links to an actual scientific paper, so it's hard to say much that's useful. Pop science articles are not good sources if you actually want to understand the science.

Thank you so much for your reply and enlightening me up on the topic :) I searched for the paper by the professor at the university and I found this, I'm not sure if its what a scientific paper per se, but it does have maths so I thought you might want to take a look. I'm sorry if its just nonsense, I'm really sorry.

http://ptep-online.com/index_files/2012/PP-31-08.PDF
http://arxiv.org/pdf/1208.5756v1.pdf

 

[PAllen]

I note that none of the 3 arxiv entries on this topic by Lebed are published in peer reviewed journals; none are cited by anyone else. It is conceivable that something will come of this, but it is premature to grant any significance to it. Of note is that many papers of Lebed on condensed matter physics are published in major journals, but not any of these papers challenging the EP. (Note: "Progress in Physics" is not listed as a citable journal in Thomson Reuters).

 

[sardar]

Hello,

Thank you for sharing your interest in the Equivalence Principle and the articles you have read. I can provide some insight into this topic.

The Equivalence Principle is a fundamental concept in physics that states that the effects of gravity and acceleration are indistinguishable. This means that an object in a gravitational field will experience the same acceleration as an object in an accelerating reference frame. This principle is a cornerstone of Einstein's theory of general relativity, which is a widely accepted theory of gravity.

However, as with any scientific theory, there are always ongoing discussions and research to further understand and refine it. The articles you have read discuss the possibility that the Equivalence Principle may not hold true in certain scenarios, particularly when considering the effects of quantum mechanics on gravity.

Quantum mechanics is a branch of physics that deals with the behavior of particles on a very small scale, such as atoms and subatomic particles. It is a highly successful theory, but it has not yet been fully integrated with the theory of general relativity. This is where the concept of quantum gravity comes in – it seeks to combine these two theories into a more comprehensive understanding of the universe.

Some theories of quantum gravity suggest that the Equivalence Principle may not hold true at a very small scale, where the effects of quantum mechanics are dominant. However, this is still an area of active research and there is currently no experimental evidence to support or refute these ideas.

So, to answer your question, the Equivalence Principle is a well-established concept in physics, but there are ongoing discussions and research to further understand its limitations and implications. As a layman, it is always helpful to stay updated on the latest developments in theoretical physics, but it is important to also keep in mind that these are still theories and may change as new evidence and ideas emerge.

I hope this helps to clarify your understanding of the Equivalence Principle. Keep exploring and learning about the fascinating world of physics!