John Conner

it doesn't sound right because ratio of distance traveled by the body to distance traveled by light is 6/28000. and the redshift definitely won't happen at the destination. it happens through time. so it already happened when they meet (little less than intended but look at the ratio, the damage is done) but it should be like what you said. because if we consider hubble constant (or if we need to, the accelerating rate) the spacetime is expanding with that rate and considering the direction of light toward body and direction of body toward earth and light ray, then expanded distance and time would be accounted for. can some one help me with this?

it is reasonable but that doesn't sound right. are you sure there won't be a redshift? do equations support this?

ok. another question. we send a light ray to a body far far away. the distance between us (earth) and the body is 1 Mpc. now if the body moves towards us and the light ray with 70km/s would there still be a redshift? or the wavelength won't change? note: 1- consider the rate of expansion of the metric as hubble's constant. it is believed to be accelerating but in this case consider it constant. 2- the distance is expanding but the body is moving towards us with the exact same rate. so it would appear that the light won't have a redshift but i'm pretty sure it will so why?

ok. i think i got everything wrong. red herring? you mean a misleading point?

Hello consider a body that is accelerating in space-time. and the length of the body is extremely large, for example one megaparsec. now we set the four-acceleration of the body as such that it will be the sum of two four-accelerations which one of them is a four acceleration in the body's length's direction and with the quantity of spacetime expansion rate and the other is a four acceleration that is perpendicular to first four-acceleration's direction and with a quantity large enough to be effective in relativity. now from a stationary observer point of view (don't be clingy, if you don't like it pick any inertial observer) how will it be observed?

nothing's impossible for imagining. does the black body exist? this is just idealized body like black body. if there was a body that could do that but not the metric itself what would have happened?

that's exactly what i'm asking. let's consider a body that is accelerating simultaneously in all directions, and for now this is hypothetical but how do we see it? i mean observing. like we examine sth in relativity. when a hypothetical body does such motion, does the observation change since it's accelerating? observations are relevant in respect to frames. since body's frame is accelerating it should change but how? (and yes my english is a little rusty... sorry)

well. we're considering... i'm just asking. how do we see it?

Okay thanks guys. another question. what about observing an accelerating body but in all dimensions? an acceleration in all directions simultaneously but for moving body with force. how do we see that?

let me put it this way. can there be such motion? i understand that currently there's no theoretical basis for this. so i just want to know is it possible to have an acceleration of A designated to all directions simultaneously? and not for the metric itself. for moving body!

I want to know about the equations of a motion that has a specific acceleration in all three dimensions simultaneously. which requires vectors that simultaneously are accelerating in all directions.

in long distances (megaparsec level) does the accelerating expansion of the universe affect on light and it's trajectory?

Yes. I said current but it wasn't accurate. thank you very much and for the first question i apologize. i meant accelerating expansion that occurs currently.

Hello I want to know which theory is more preferable among astrophysicists about the current expansion of the universe? i mean between cosmological constant or quintessence or something else? and one more thing. what represents the expansion in equations for examining long distances ( megaparsec level ) ? Q? hubble constant? cosmo constant? (and i mean the accelerating expansion. the parameter for accelerating space)