Insights Blog
-- Browse All Articles --
Physics Articles
Physics Tutorials
Physics Guides
Physics FAQ
Math Articles
Math Tutorials
Math Guides
Math FAQ
Education Articles
Education Guides
Bio/Chem Articles
Technology Guides
Computer Science Tutorials
Forums
Trending
Log in
Register
What's new
Latest activity
Register
Menu
Log in
Register
Navigation
More options
Style variation
System
Light
Dark
Contact us
Close Menu
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Forums
PeterDonis's latest activity
PeterDonis
replied to the thread
A
Dirac's integral for the energy-momentum of the gravitational field
.
You can't--at least, not if you're going to take the viewpoint of Dirac (and L-L, for that matter) that it's perfectly okay to write...
Sep 14, 2025
PeterDonis
replied to the thread
A
Dirac's integral for the energy-momentum of the gravitational field
.
I know you are. And you have not responded at all to my argument in post #13 for why that is not correct--why ##T_{\mu \nu}##, with two...
Sep 14, 2025
PeterDonis
replied to the thread
A
Dirac's integral for the energy-momentum of the gravitational field
.
Only if you think ##T^{\mu \nu}## represents what I've said it doesn't represent, and explained why. I can't remember if L-L use the...
Sep 14, 2025
PeterDonis
replied to the thread
A
Dirac's integral for the energy-momentum of the gravitational field
.
Well, let's see. $$ M^{\mu \nu} = g^{\mu \alpha} M_\alpha{}^\nu $$ Therefore, $$ M^{\mu \nu}_{,\nu} = \left( g^{\mu \alpha}...
Sep 14, 2025
PeterDonis
replied to the thread
I
Question about discussions around quantum interpretations
.
Yes, but now it's the state of atom plus environment, not just the state of the atom.
Sep 14, 2025
PeterDonis
replied to the thread
I
Question about discussions around quantum interpretations
.
You can--by creating an environment where the quantum states of the decay products are already occupied, or partially occupied. (And for...
Sep 13, 2025
PeterDonis
reacted to
pervect's post
in the thread
I
Symmetry of motion in the special theory of relativity
with
Like
.
So far, so good. You have described the symmetry principle of relativity well. And it is indeed puzzling how this is possible - at...
Sep 13, 2025
PeterDonis
replied to the thread
I
Hawking After 54 Years Confirmed: BH surfaces don't shrink
.
As you seem to realize now, it isn't. It's a mathematical theorem. The main thing to understand about it, as you saw from the paper, is...
Sep 13, 2025
PeterDonis
replied to the thread
I
Hawking After 54 Years Confirmed: BH surfaces don't shrink
.
What's the difference?
Sep 13, 2025
PeterDonis
replied to the thread
I
A sufficient condition for integrability of equation ##\nabla g=0##
.
Sorry, this is simply wrong. We can't have a useful discussion if you continue to make wrong claims after repeated corrections. Thread...
Sep 13, 2025
PeterDonis
replied to the thread
I
A sufficient condition for integrability of equation ##\nabla g=0##
.
The tetrad in that expression is not the holonomic frame ##\partial_\mu##. It's the expressions ##X_i = h^\mu_i \partial_\mu##. The...
Sep 13, 2025
PeterDonis
replied to the thread
A
Dirac's integral for the energy-momentum of the gravitational field
.
It isn't. I explained what is in my previous post. It's a pseudotensor, not a tensor (because ##t## is a pseudotensor, not a tensor)...
Sep 13, 2025
PeterDonis
replied to the thread
I
A sufficient condition for integrability of equation ##\nabla g=0##
.
Please give a reference for this claim. I have never said any such thing. All I have said is that the Levi-Civita connection has...
Sep 12, 2025
PeterDonis
reacted to
gmax137's post
in the thread
Other
Don’t have a high enough IQ for physics so I want to give up
with
Like
.
I think everything in your post (after the first sentence) is incorrect. Here's what I know: Online IQ tests are meaningless Those...
Sep 12, 2025
PeterDonis
reacted to
Nugatory's post
in the thread
B
What qualities does time have other than linearity, motion, and speed?
with
Like
.
There's no sensible answer to your question until you have defined what you mean by the word "time". This being a physics forum where we...
Sep 12, 2025
Forums
Back
Top