Re: Want to prove E=mc²? University labs should try this!

On Wed, 20 Nov 2024 14:46:05 +0000, rhertz wrote:

As I wrote before, the cavity NEVER reaches a steady state (thermal
equilibrium is just one possible goal to reach a steady state).
>
The stored energy increases constantly until the temperature of the
cavity
walls (not cancelled by any means) destroy the material that form the
cavity (either coatings or places on the cavity surface, making holes).

No, because the temperature of the foil rises until the power emitted
equals 5 watts. Once that happens, no further increase of stored
energy occurs.
P = ε * σ * T^4
Let us assume a 10x10x10 cm cube with surface area 0.06 m^3
So 5 watts total power emitted means 83 watts/m^2
Assume ε = 0.13
Let T_i be 273 K
83 = ε * σ * (T_f^4 - T_i^4)
11,260,344,593 = (T_f^4 - 5,554,571,841)
T_f = 274.8 K
In other words, the temperature of the foil rises to 1.8 degrees
above room temperature.

In physics, a steady state is a condition in which a system or process
does not change over time, or any changes are balanced out. This means
that the variables that define the system's behavior remain constant.
Some examples of steady states include:
>
Bathtub with a running tap: After a while, the water level stabilizes
and the system is in a steady state.
>
Thermal equilibrium: Two systems are in thermal equilibrium when they
are at the same temperature and there is no heat flow between them.
>
In 72 hours none of these conditions are reached: No steady state nor
thermal equilibrium. The inner temperature increase constantly, due to
the accumulation of energy within the cavity.
>
Regarding the orifice used to inject the laser beam, I always thought of
using a directional micro-glass window that reflects, internally, laser
hits.