Physics Help Forum The formula E = mc^2 never have been proved?

 Special and General Relativity Special and General Relativity Physics Help Forum

 Feb 21st 2018, 04:20 PM #11 Junior Member   Join Date: Feb 2018 Posts: 7 I heard of something called Einstein's box which could yield the equivalence without working with the gamma factor. Is it true? Last edited by Ziang; Feb 21st 2018 at 04:28 PM.
 Feb 21st 2018, 05:39 PM #12 Senior Member   Join Date: Aug 2010 Posts: 418 No, 'Einstein's Box' has to do with quantum theory, not relativity. It is mentioned here: https://en.wikipedia.org/wiki/Bohr%E...#39;s_argument topsquark likes this.
Feb 22nd 2018, 02:09 AM   #13
Senior Member

Join Date: Oct 2017
Location: Glasgow
Posts: 395
 Originally Posted by Ziang Is there any way to modify Newtonian mechanics so that the equivalence can be derived from classical concepts in absolute space and time?
Just nope.

Feb 22nd 2018, 06:47 AM   #14
Physics Team

Join Date: Apr 2009
Location: Boston's North Shore
Posts: 1,576
 Originally Posted by Ziang I heard of something called Einstein's box which could yield the equivalence without working with the gamma factor. Is it true?
Einstein used more than one boxes in his writing. You're thinking of the one where he deduced the equivalence of mass and energy of electromagnetic radiation. There is no gamma factor in that derivation since there's no gamma factor when E = mc^2 relates the mass and energy of EM radiation.

You can follow the derivation at my website at
Einstein?s Box

In this page I derived the equivalence of mass and energy for tardyons (particles that move at speeds v < c)
Mass Energy Equivalence

Caution: There are a few mistakes in that page which I haven't corrected yet. I referred to equation numbers which aren't in that page. I'll eventually fix hem.

Feb 23rd 2018, 06:46 AM   #15
Junior Member

Join Date: Feb 2018
Posts: 7
 Originally Posted by benit13 Just nope.
I found some educational links and textbooks which use the box to derive the equivalence.

Feb 23rd 2018, 07:02 AM   #16
Junior Member

Join Date: Feb 2018
Posts: 7
 Originally Posted by Pmb Einstein used more than one boxes in his writing. You're thinking of the one where he deduced the equivalence of mass and energy of electromagnetic radiation. There is no gamma factor in that derivation since there's no gamma factor when E = mc^2 relates the mass and energy of EM radiation. You can follow the derivation at my website at Einstein?s Box
So the equivalence can be derived without dealing with gamma factor or relative spacetime, right?

Feb 23rd 2018, 07:14 AM   #17
Senior Member

Join Date: Oct 2017
Location: Glasgow
Posts: 395
 Originally Posted by Ziang I found some educational links and textbooks which use the box to derive the equivalence.
Okay, but I doubt very much that the derivation came from classical mechanics.

Can you please provide the links and textbook details so I can investigate?

Feb 23rd 2018, 03:38 PM   #18

Join Date: Apr 2008
Location: On the dance floor, baby!
Posts: 2,730
 Originally Posted by Ziang I found some educational links and textbooks which use the box to derive the equivalence.
 Originally Posted by Ziang So the equivalence can be derived without dealing with gamma factor or relative spacetime, right?
Again. No.

As with benit13 I would like to see what sources you are using to say this.

-Dan
__________________
Do not meddle in the affairs of dragons for you are crunchy and taste good with ketchup.

See the forum rules here.

 Feb 24th 2018, 07:51 AM #19 Junior Member   Join Date: Feb 2018 Posts: 7 This is a link galileo.phys.virginia.edu/classes/252/mass_and_energy.html
 Feb 24th 2018, 09:12 AM #20 Physics Team   Join Date: Apr 2009 Location: Boston's North Shore Posts: 1,576 benit13, Dan - Have you read Einstein's 9105 paper on mass-energy equivalence.? Einstein didn't use the gamma factor because the derivation was for a slowly moving body. When he later derived the same result for EM radiation there too the gamma factor is absent. Its only for a particle moving at a speed comparable to the speed of light that gamma comes into play. In that case it cannot be avoided. topsquark likes this.

 Tags formula, mc2, proved

 Thread Tools Display Modes Linear Mode

 Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post ling233 Advanced Mechanics 0 Jan 20th 2016 04:11 PM Xp96 Atomic and Solid State Physics 1 May 28th 2013 07:33 AM jonbrutal Kinematics and Dynamics 0 Feb 14th 2010 06:57 AM kenny1999 Light and Optics 1 Sep 2nd 2009 11:48 PM kdaaa Advanced Mechanics 1 Mar 11th 2009 12:48 AM