Can a nuclear reaction violate the first law of classical thermodynamics?

  • Thread starter Thread starter Felgar
  • Start date Start date
  • Tags Tags
    Reference
AI Thread Summary
Nuclear reactions do not violate the first law of thermodynamics; instead, they illustrate the need to unify the laws of conservation of mass and energy as established by Einstein's theory of relativity. Before this unification, classical thermodynamics treated mass and energy as separate entities, leading to apparent violations during nuclear processes. The discussion highlights the importance of understanding that mass-energy equivalence (E=mc^2) allows for a comprehensive conservation law. The argument centers on the interpretation of classical versus modern thermodynamics, emphasizing the evolution of scientific understanding. Ultimately, the consensus is that nuclear reactions are consistent with the first law when viewed through the lens of modern physics.
Felgar
Messages
19
Reaction score
0
Hi Guys,

I'm in an argument with someone on another forum (car forum no less) and he refuses to accept that nuclear reactions break the first law of classical thermodynamics. I'm only trying to show him that before energy and mass were shown to be interchangeable, the laws of conservation energy and of conservation of mass is the classical sense are violated by nuclear/radioactive processes. However, it's so commonly accepted now that mass-energy is conserved together rather than seperately, I can't find a valid and credible source that distinguishes between classical and more modern thermodynamics.

Can anyone help with a link? Thanks guys.
 
Physics news on Phys.org
I am not aware of nuclear reactions breaking any laws of thermodynamics.
 
Just that taken separate from each other, the laws of conservation of mass and conservation of energy don't hold, because we'll lose mass in a nuclear reaction. Not until the revelation that e=mc^2 and the combination of the two laws do we actually get a conservation law that is not broken.

quoted from
Relativity, the Special and General Theory
by Dr. Einstein

"Before the advent of relativity, physics recognized two conservation laws of fundamental importance, namely the law of conservation of energy and the law of the conservation of mass; these laws appeared to be quite independent of each other.
By means of the theory of relativity they have been united into one law... "
 
You shouldn't see this as a violation of the 1st law of thermodynamics, you should rather consider that in the first law, energy can now (since Einstein) include what is available through E = mc^2 in the case where you have nuclear reactions.
 
Alrighty then... No wonder it was hard to find that reference. Heh.

And yeah, obviously that's what makes the most sense. But the argument was about the classical definition which I was arguing wuold have to be observed in the strictest sense. But yeah, whatever.
 
Last edited:
Thread 'Gauss' law seems to imply instantaneous electric field'
Imagine a charged sphere at the origin connected through an open switch to a vertical grounded wire. We wish to find an expression for the horizontal component of the electric field at a distance ##\mathbf{r}## from the sphere as it discharges. By using the Lorenz gauge condition: $$\nabla \cdot \mathbf{A} + \frac{1}{c^2}\frac{\partial \phi}{\partial t}=0\tag{1}$$ we find the following retarded solutions to the Maxwell equations If we assume that...
Maxwell’s equations imply the following wave equation for the electric field $$\nabla^2\mathbf{E}-\frac{1}{c^2}\frac{\partial^2\mathbf{E}}{\partial t^2} = \frac{1}{\varepsilon_0}\nabla\rho+\mu_0\frac{\partial\mathbf J}{\partial t}.\tag{1}$$ I wonder if eqn.##(1)## can be split into the following transverse part $$\nabla^2\mathbf{E}_T-\frac{1}{c^2}\frac{\partial^2\mathbf{E}_T}{\partial t^2} = \mu_0\frac{\partial\mathbf{J}_T}{\partial t}\tag{2}$$ and longitudinal part...
Back
Top