Uncovering the Mystery: 2D Creatures on Expanding Sphere

  • Thread starter Thread starter Behrad
  • Start date Start date
  • Tags Tags
    Expanding Sphere
Behrad
Messages
2
Reaction score
0
Some 2D creatures are living on a sphere that it radius in increasing over time. They think that they are living on a expanding plane. The max speed of information is speed of light. The life time of the creatures are very smaller that the radius divided by speed of light. How can they find out they are living on a sphere. I tried to use doppler effect but it couldn't

P.n. Sorry for my bad english!
 
Physics news on Phys.org
I also wrote the doppler effect equations but the effect was very small that they couldn't notice.

And my problem depends on the amount of dR/dt
 
Thread 'Need help understanding this figure on energy levels'

Thread 'Need help understanding this figure on energy levels'

This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
View full post »
Thread 'Understanding how to "tack on" the time wiggle factor'

Thread 'Understanding how to "tack on" the time wiggle factor'

The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
View full post »

Similar threads

Evaluating an integral for an expanding, charged sphere
Replies
2
Views
3K
I Why does Hubble sphere expand with time?
Replies
13
Views
3K
Intensity of Stars and the Inverse Square Law Problem
Replies
10
Views
3K
Why is the Hubble sphere expanding?
Replies
16
Views
13K
I Is this explanation of "space itself expanding" correct?
Replies
27
Views
4K
I How do you get to the conclusion that there is accelerating expansion?
Replies
23
Views
2K
Too Much Stellar Flux: Fixing a 25-year old Problem
Replies
9
Views
3K
Is the Universe Really Expanding?
3
Replies
104
Views
35K
Writing: Input Wanted Generation Ship SFV Exodus: Revised Designs
2
Replies
52
Views
7K
I Some questions about Cosmic Inflation
Replies
4
Views
4K

Hot Threads

Recent Insights

Back
Top