Matter-antimatter ship in GR clock paradox - fuel consumption

malin
Messages
1
Reaction score
0
hi,

recall the familiar round trip - it's more or less the same as in this arXiv article (http://arxiv.org/PS_cache/physics/pdf/0604/0604025v3.pdf) - round trip with acceleration g. me and my friends were wondering the following:
imagine that the passenger abroad the rocket travels for 4 years and the ship alone is 1000t. (or any other number, it doesn't matter)
how much matter-antimatter (100% efficiency, E=mc2) fuel would the ship need?

we don't even agree wheter m(t) is trivial from the boundary conditions, let alone m(x),
and we are working in GR framework...
can anyone tell me how to solve this one?


thanks!
 
Physics news on Phys.org
Hi malin, welcome to PF,

The http://www.math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html" page covers all of this. For a 4.3 light-year trip stopping at the end you require 38 kg of fuel (at 100% efficiency) for every 1 kg of payload.
 
Last edited by a moderator:

Thread 'Euclidean geometry and gravity'

I asked a question here, probably over 15 years ago on entanglement and I appreciated the thoughtful answers I received back then. The intervening years haven't made me any more knowledgeable in physics, so forgive my naïveté ! If a have a piece of paper in an area of high gravity, lets say near a black hole, and I draw a triangle on this paper and 'measure' the angles of the triangle, will they add to 180 degrees? How about if I'm looking at this paper outside of the (reasonable)...
View full post »

Thread 'Is the variation of the metric ##\delta g_{\mu\nu}## a tensor?'

From $$0 = \delta(g^{\alpha\mu}g_{\mu\nu}) = g^{\alpha\mu} \delta g_{\mu\nu} + g_{\mu\nu} \delta g^{\alpha\mu}$$ we have $$g^{\alpha\mu} \delta g_{\mu\nu} = -g_{\mu\nu} \delta g^{\alpha\mu} \,\, . $$ Multiply both sides by ##g_{\alpha\beta}## to get $$\delta g_{\beta\nu} = -g_{\alpha\beta} g_{\mu\nu} \delta g^{\alpha\mu} \qquad(*)$$ (This is Dirac's eq. (26.9) in "GTR".) On the other hand, the variation ##\delta g^{\alpha\mu} = \bar{g}^{\alpha\mu} - g^{\alpha\mu}## should be a tensor...
View full post »

Similar threads

I Twin paradox, virtual clock on ship with Earth time, discontinuity
3
Replies
115
Views
8K

Hot Threads

Recent Insights

Back
Top