# Recent Activity

1. ### JohnNemo replied to the thread Insights "Classical Physics Is Wrong" Fallacy - Comments.

Exactly, but I’m not sure this point comes out clearly in your article. To say that 1. Newton was wrong (about a lot of things) is not...

Mar 18, 2018 at 3:29 AM
2. ### David Prince liked mfb's post in the thread B Gravity and human population. SOLVED..

As indicated, the mass of all humans comes from Earth and does not change the overall mass of Earth. It is unclear if we gain more mass...

Mar 18, 2018 at 3:20 AM
3. ### tech99 replied to the thread I One particle and two-slits.

I think it it true that after a period of time, a pattern of dots will build up. I am not sure why your pattern does not taper away from...

Mar 18, 2018 at 3:16 AM
4. ### NebulaBilly liked JMz's post in the thread I Recession speed of a galaxy.

Souds good. I imagine this galaxy already has a published distance somewhere. Did you check if 60 Mpc is about right?

Mar 18, 2018 at 3:00 AM
5. ### NebulaBilly replied to the thread I Recession speed of a galaxy.

All looks good atleast can see how they got there now, sometimes the simplest way seems the most difficult.

Mar 18, 2018 at 2:59 AM
6. ### Nguyen Son liked Orodruin's post in the thread Other Mathematical Methods for Physics and Engineering.

First of all: Always mention not only the book title, but also the author(s). If you do not there may generally be degeneracies such as...

Mar 18, 2018 at 2:48 AM
7. ### Stavros Kiri attached a file to the thread I Non Newtonian / Newtonian Fluid interface.

For water waves "In water whose depth is large compared to the wavelength, the wave speed expression contains two terms, one for gravity...

Mar 18, 2018 at 2:41 AM
8. Phys12 posted a new thread.

### I Probability of getting 3 out of 4 numbers correct

Problem statement: In a lottery, players win a large prize when they pick four digits that match, in the correct order,four digits...

#### Forum: Set Theory, Logic, Probability, Statistics

Mar 18, 2018 at 2:40 AM
9. ### Phys12 liked Vanadium 50's post in the thread I Feynman Diagram-Momentum conservation in primitive vertex.

Yes. And Griffiths agrees with me. See his preface.

Mar 18, 2018 at 2:39 AM
10. ### craigthone replied to the thread Field transformation under Conformal transformation.

Thanks for you explaination, samalkhaiat. It still has some problem : under $x \rightarrow \bar{x}$, what does the field $\phi(x)$...

Mar 18, 2018 at 2:39 AM
11. ### craigthone liked samalkhaiat's post in the thread Field transformation under Conformal transformation.

Both are correct. However, the \lambda in the first is \lambda^{-1} in the second. To see this, start from the first transformation law...

Mar 18, 2018 at 2:32 AM
12. ### haruspex replied to the thread Centripetal/Centrifugal Motion on a merry-go-round.

They cannot both be true. It should be evident that Ft>mg. Nonsense. As vectors they are not in the same direction, but including a...

Mar 18, 2018 at 2:29 AM
13. ### AlexCaledin attached a file to the thread PF Photo Contest - It's Not That Easy (3/17-3/23).

It's not that easy, to move this ball: [ATTACH]

Mar 18, 2018 at 2:22 AM