# Einstein box : an entering photon

I was wondering if anyone considered a photon entering the Einstein-box, say because outside is 'hotter'. Would an increase in mass-energy be observable? Some may consider this a trivial question but I'm asking anyway.

The 'Einstein box' is a thought-experiment Einstein proposed to observe both the size of an energy change & the time at which it came to be.

A box has a 'perfect' shutter so you can let just 1 photon exit. The mass of the is box is decreased because the photon carries away energy ($$E=mc^2$$). The box is weighed before and after so you know the energy of the photon and the 'perfect' shutter allows you to know when the photon exited. Knowing both energy & time of course violates Heisenberg. Bohr showed that Einstein proposal was flawed.

I hope this is clear enough?

• I don't think I understand what you are asking. What do you mean by "the Einstein box". Can you edit your question to be more specific about what you are asking? – Paul T. Oct 31 at 17:57
• With "the Einstein box" I'm talking about the thought-experiment Einstein proposed 2 show that it is possible to measure both the size of an energy change and the time at witch it came 2 be. A box has a perfect shutter, allowing to let just 1 photon 2 exit. The mass of the box will decrease because the photon carries away energy. Because the shutter is 'perfect' U know when U opened it. This experiment would allow U to know both 'time'&energy' violating Heisenberg. Bohr showed that the experiment is 'flawed'. My question is simply: Could a photon enter instead of leaving and would U know it? – Orlando Marchena Oct 31 at 19:52