Mr. Tompkins in Wonderland - a clarification

  • Thread starter Thread starter ahaanomegas
  • Start date Start date
ahaanomegas
Messages
28
Reaction score
0
I don't have the book Mr. Tompkins in Wonderland, but I have heard about it. A little introduction is needed. Mr. Tompkins lives in a world where the speed of light is 20 mph. Here, of course, relativity must be taken into account almost always. I was wondering about length contraction, though. If Mr. Tompkins is riding his bike at a speed close to that of light, he looks thinner to those standing on the sidewalk and the men on the sidewalk look fatter to Mr. Tompkins. Am I right? I'm a little confused about that about what is seen to whom and who sees what.

Thanks in advance!
 
Physics news on Phys.org
No. If Mr Topkins is moving at speed v relative to the people on the side walk, then they are moving at speed v relative to him. He sees them as thinner and they see him as thinner than if they were motionless relative to him.
 
Nice link, thanks.
 

Thread 'Describing the Big Bang'

I started reading a National Geographic article related to the Big Bang. It starts these statements: Gazing up at the stars at night, it’s easy to imagine that space goes on forever. But cosmologists know that the universe actually has limits. First, their best models indicate that space and time had a beginning, a subatomic point called a singularity. This point of intense heat and density rapidly ballooned outward. My first reaction was that this is a layman's approximation to...
View full post »
Thread 'Dirac's integral for the energy-momentum of the gravitational field'

Thread 'Dirac's integral for the energy-momentum of the gravitational field'

See Dirac's brief treatment of the energy-momentum pseudo-tensor in the attached picture. Dirac is presumably integrating eq. (31.2) over the 4D "hypercylinder" defined by ##T_1 \le x^0 \le T_2## and ##\mathbf{|x|} \le R##, where ##R## is sufficiently large to include all the matter-energy fields in the system. Then \begin{align} 0 &= \int_V \left[ ({t_\mu}^\nu + T_\mu^\nu)\sqrt{-g}\, \right]_{,\nu} d^4 x = \int_{\partial V} ({t_\mu}^\nu + T_\mu^\nu)\sqrt{-g} \, dS_\nu \nonumber\\ &= \left(...
View full post »

Thread 'A sufficient condition for integrability of equation ##\nabla g=0##'

In Philippe G. Ciarlet's book 'An introduction to differential geometry', He gives the integrability conditions of the differential equations like this: $$ \partial_{i} F_{lj}=L^p_{ij} F_{lp},\,\,\,F_{ij}(x_0)=F^0_{ij}. $$ The integrability conditions for the existence of a global solution ##F_{lj}## is: $$ R^i_{jkl}\equiv\partial_k L^i_{jl}-\partial_l L^i_{jk}+L^h_{jl} L^i_{hk}-L^h_{jk} L^i_{hl}=0 $$ Then from the equation: $$\nabla_b e_a= \Gamma^c_{ab} e_c$$ Using cartesian basis ## e_I...
View full post »

Similar threads

Does light exist outside of time ?
Replies
5
Views
3K
B Calculating Time taken to reach speed with Time Dilation
Replies
18
Views
1K
Who Hits Wall First: Light Beam or Light Traveller?
Replies
5
Views
2K
B Does the size of the Universe change with motion?
Replies
13
Views
2K
I Is the premise of the Michelson–Morley argument still valid?
Replies
31
Views
3K
Measurement of relativistic effects from a non-inertial frame
Replies
5
Views
3K
I SR Light Wavelength & Direction: Questions Explained
Replies
6
Views
2K
I How Does the Twin Paradox Apply to Light and Sound Waves?
Replies
48
Views
5K
A What was the explanation of OPERA superluminal neutrinos?
Replies
14
Views
2K
Speed of Light in Special Relativity: Explained & Questioned
Replies
1
Views
2K

Hot Threads

Recent Insights

Back
Top