A Conversation for Universal Red Shift

A614116 - Universal Red Shift

Post 1

WeS

http://www.bbc.co.uk/h2g2/guide/A614116

I wrote this entry a while ago after some questions by another researcher. Since then I've had a few hints and added those. Are there any other edits I should make if I am to submit it to Peer Review?

WebSherpa


A614558 - Universal Red Shift

Post 2

WeS

smiley - doh

I've linked to the wrong page! smiley - steam

I meant:

http://www.bbc.co.uk/h2g2/guide/A614558

(I copied the wrong shortcut!)


A614558 - Universal Red Shift

Post 3

Monsignore Pizzafunghi Bosselese

The explanation of Doppler shift isn't really precise: the waves aren't squashed or stretched, they only *appear* like that because if the receiver is moving 'into' the wave it will encounter more maxima and minima per second than if it was stationary (likewise for the case of a 'receding' receiver). If the transmitter is moving then it still creates maxima/minima at the rate which is given by the frequency, but these m./m. are emitted from different places and propagate with the same speed, hence an observer will measure a different frequency.


You could perhaps mention the reference point for the red/blue shift.. how do we know that the light underwent Doppler shift, rather than having been emitted from a stationary object just the way we see it? Ok, you and I know that it's the axiom (fact?) that hydrogen is the same everywhere in the Universe, irrespective of its whereabouts, and hence its absorption/emission lines are the same everywhere, so if you see 'hydrogen' spectra which aren't where you would expect them then you have reason enough to suspect a Doppler shift behind the effect.

Other than that, off you go to the Peer Review smiley - smiley


A614558 - Universal Red Shift

Post 4

WeS

In the reference frame of the receiver the wave *is* squashed and streched. As it's a bit confusing I'll rewrite that though.

Relativity! smiley - headhurts

Occam's Razor: Hydrogen *is* the same everywhere in the universe. smiley - earth

WS


Thread Moved

Post 5

h2g2 auto-messages

Editorial Note: This conversation has been moved from 'The Writing Workshop' to 'Universal Red Shift'. Hi folks, this thread has been moved back to the entry as a new PR thread exists for the updated entry: http://www.bbc.co.uk/h2g2/guide/F48874?thread=142031.


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