telescope question

[hoola]

would a telescope looking forward on a speeding rocket see the distant red shifted galaxies with less shift? If the speed of travel was close to light, would a telescope see previously unseeable galaxies, past the normal light cone limitation? If a ship were to travel at or above light speed, would it be able to see the BB?

[hoola]

a space telescope sitting in deep space. Forward of the scope is a galaxy "A" that is redshifted to a certain amount "R". Directly behind the space telescope is a similar galaxy at the same redshift. If the space telescope advances towards galaxy A at 90%C and records the redshift, and then reverses and goes the opposite direction at the same speed, will the same redshift be recorded for galaxy B? Wouldn't a slightly uneven averaged spatial expansion of space cause the two measured redshifts to differ slightly? And wouldn't a stationary telescope measure tiny real time redshift changes in observing galaxy "A", as gravity wave noise randomly shifts the observed spectrum of galaxy "A"?

Edited August 30, 2014 by hoola

[imatfaal]

would a telescope looking forward on a speeding rocket see the distant red shifted galaxies with less shift? If the speed of travel was close to light, would a telescope see previously unseeable galaxies, past the normal light cone limitation? If a ship were to travel at or above light speed, would it be able to see the BB?

 

Red-shifted light isn't slowed it is red-shifted. If you were travelling at a decent speed you would un-red-shift the light to an extent (and shift even more the stuff you were moving away from). But the light cone is based on position - and two observers co-located but one travelling and the other relatively stationary would experience the same events - and could use mathematical transformations to understand/predict what the other was seeing.

[hoola]

so, a person at position X who is stationary would view the same depth of light cone as a person going at the speed of light as that person also crosses (near) positon X? (Both looking in the same direction)...it seems to me the light cone would be extended somewhat as the infrared and microwave red-shifted light was raised in frequency to become visible to the moving observer only...Actually I am more interested in the question of gravity waves being detectable with long term analysis of quick variations present in red shift measurements of distant galaxies, as a sort of gravity wave weather report for the region containing our galaxy. Presumably it would be an averaged chaotic noisey area due to many sources adding and nulling, but with really big occasional signals due to black hole collapses and such from certain directions...

Edited September 1, 2014 by hoola

[imatfaal]

all light travels in the vacuum at the same speed regardless of wavelength.

 

so, a person at position X who is stationary would view the same depth of light cone as a person going at the speed of light as that person also crosses (near) positon X? (Both looking in the same direction)...it seems to me the light cone would be extended somewhat as the infrared and microwave red-shifted light was raised in frequency to become visible to the moving observer only...

 

But a stationary observer can measure the infrared and the microwave. We do it all the time - how else would we know about the CMBR? We observe much in the radiowave band - that's the light which has been very redshifted. There will, and this is a huge guess, a tiny section of very redshifted radio that is beyond the limit of resolution to a stationary observer but which would be blueshifted back to within the limit by a fast travelling observer; I really do not know if this is true and in any case it is always within both observers lightcone

...Actually I am more interested in the question of gravity waves being detectable with long term analysis of quick variations present in red shift measurements of distant galaxies, as a sort of gravity wave weather report for the region containing our galaxy. Presumably it would be an averaged chaotic noisey area due to many sources adding and nulling, but with really big occasional signals due to black hole collapses and such from certain directions...

 

Well to an extent we do already do this - bit of a stretch tho. The Bicep2 (I started a longish thread in news section on it) experiment used the fact that gravitational waves will create specific patterns of polarization in the CMBR - this allowed a deeper investigation of the conditions prior to the formation of the cmbr and possibly even the fluctuations that were present in the inflation period. We cannot yet detect "raw" gravitational waves - but we are in no doubt they exist; the indirect measurement of them is so amazing close to predictions, and we are already at a point where we can use the action of gravitational waves to investigate other phenomena. That doesn't mean there wont be a trip to oslo for the first team to actually nail a significant direct measurement

[hoola]

my interests deal strictly with frequency of light, no mention of it's speed. The only speed relevant to any question was of the observer...increasing the frequency of distant light from infrared into the visible, thereby extending the light cone perhaps a bit to a fast observer...I look forward to getting gravity waves to replace traditional radio/microwaves for communications..I presume this is technically possible...

[imatfaal]

my interests deal strictly with frequency of light, no mention of it's speed. The only speed relevant to any question was of the observer...increasing the frequency of distant light from infrared into the visible, thereby extending the light cone perhaps a bit to a fast observer...I look forward to getting gravity waves to replace traditional radio/microwaves for communications..I presume this is technically possible...

 

Yes but the past light cone is that volume of spacetime within which events can be observed and that volume is determined by the speed of light. You cannot alter the volume of the light cone of past observable events that exists at a point and time. You have again repeated the phrase "extending the light cone" - you cannot do this; the light cone is that volume of spacetime which is causally in future light cone and observationally in the past light cone connected to the agent. It is a theoretical boundary that marks out the volume of space that light can travel in the amount of time - the colour of that light has nothing to do with it.

 

why would we want to use gravitational waves (try that formation rather than gravity waves as this can be ambiguous) rather than radio waves I do not know. We can detect radio waves from the distant edge of the observational universe - we are yet to directly detect gravitational waves; why make it difficult for ourselves?

[hoola]

yes, light cone was a misnomer...I meant extending distant visible observations of the infrared into the visible spectrum, of which were visible to the eye before they were stretched by space...I would think (hope) a gravitational wave based cell phone wouldn't give you brain cancer...or need those awful, ugly blinking antennas...and that any advanced species would have this and be doing a search for us with gravitational waves along with regular emf as part of it's seti program...

[imatfaal]

yes, light cone was a misnomer...I meant extending distant visible observations of the infrared into the visible spectrum, of which were visible to the eye before they were stretched by space..

 

We can do that with a desktop pc - how do you think you see those lovely pictures taken by various infrared space telescopes

 

 

This is a photo from Spitzer - taken in the infra-red and mapped with false colour to be visible to us.

 

...I would think (hope) a gravitational wave based cell phone wouldn't give you brain cancer...or need those awful, ugly blinking antennas...

 

I don't know where you get your phone - but mine has no externally obvious antenna (neither do most phones now) nor do they give you brain cancer

 

...and that any advanced species would have this and be doing a search for us with gravitational waves along with regular emf as part of it's seti program...

 

But how would we be making gravitational waves that would be detectable above background