h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I still think you need to explain what the device is used *for*, so that science dimwits like me can make sense of it all. What kind of experiment would you use it in, and why? This needs to go right at the start.

Otherwise, as I said, this is good work

Ok, I think I've taken care of what was mentioned. I know the heading s are a little silly, but I'll change them when I can come up with better ones, I'm a little tired.

IN relation to Michelson & Morleys exp having fixed mirrors, Yes I know, but thats a different entry. I'll work on that one later.

Thanks for the comments though.

'Ok, I think I've taken care of what was mentioned.'


As I have said, twice already:

I still think you need to explain what the device is used *for*, so that science dimwits like me can make sense of it all. What kind of experiment would you use it in, and why?

Without something to give it context, the average reader (or Scout) will not have a clue what you're talking about and why. For someone to pick this for the Guide, first they have to understand it. Please help us to do that

Thanks!

WHats wrong with the last paragraph? That's what it's used for.

It still doesn't explain what you are trying to measure, why you are trying to measure it or give any clue as to what the experiment is for!

Hi Paudie,

I tend to agree with Skankyrich. From the perspective of a non-expert it is difficult to see what the benefit of the apparatus is.

I can see a few reasons why an interferometer might be used.

a) it can be used to measure the wavelength, and thus the frequency of light rays.

b) from this it can be used to break a light emission into its component parts, thus enabling the different wavelengths to be measured.

c) from this you can take a light source like a star, find out what its emission spectrum is, match it to the pure emissions spectrums of well known elements like hydrogen and helium, and devise what it is made of, and what type of star it is. You can take recordings of spectral changes over time to find out if there is a binary star there, or maybe even a planet system. You could also find out how fast a very distant star is moving away from us based on its 'red shift', and thus its distance from us.

d) interferometers widely separated from each other can be used to create a really huge telescope - the small differences in light reaching both telescopes should be able to provide added detail about the star or astronomical object.

e) for use as a high precision ruler. I imagine you could use one of these things to measure the distance from the moon to the earth, possibly to the nearest centimetre.

e) it probably could even be used to measure the speed of light, as was done in the Mitchelson / Morley experiment?

That kind of stuff. There may be other uses as well which I don't know of. Could this kind of device be used in crystallography for instance to determine the crystal structure of a material? It seems possible.

Interferometry is not very easy to define!

It's a branch of science in which waves travelling on different paths are combined. Because waves either reinforce or cancel one another according to their phase, an interferometer can be used to measure the difference in the length of the wave-paths to an accuracy of order of the wavelength.

In the set-up described (a Michelson interferometer), that means you can measure distances to an accuracy of about one part in a thousand-million using visible light.

There are all sorts of ways you can extend the principle to do other things, but the fundamental use from WP's list is as a high-precision ruler.

That's the kind of explanation that's needed in the entry, not on the thread

Even a cursory google reveals lots of definitions that any member of the public can understand (yes, even me). The problem with this entry is that it seems to start in the middle - it doesn't give any reason or explanation why you would want to do this! I've said that the explanation of the experiment is quite good, but the big question is: Why? As it goes, I have no idea why you would do this from reading the entry alone.

I did mention this seven months ago....

Err, it doesn't seem to have changed. At least none of my comments have gone in.

Oh my surfboard, now I see why you are all giving out. I actually did change a good bit of it, but I appear not to have saved it or something. Bugger. Ok I'll get working, again. *sigh*

Okay sorry about the mix up

Hopefully this works this time. Let me know what's wrong this time

Yup, much better. Only thing I would say is change the heading "Use of the interferometer", as the final para is titled "Uses of the interferometer", but I couldn't come up with an alternative...

It's a lot better, but for me it's still not quite there Sorry...

I've just read a great entry in PR on e-MERLIN, which makes a lot of complicated science stuff accessable to the rest of us. It includes a great description of a use of inferometery in astronomy. I really feel that it is this kind of description we are looking for in your work.

Hope this helps, the entry I refer to is A3978174.

I've absolutely no experience of an interferometer in that context, only what I've described. Therefore my infomation not being complete, should I pull the plug on this entry?

Don't chuck in the - don't forget you titled this 'The Interferometer - Not Technical'

You need to just try and add some more uses if you can!

I'll try and re-read and comment later...

Speller

Could you change the title to reflect that you're discussing one specific experiment?

Can I propose a move to the Fleamarket?

Sure

Can I get an amen?

Seconded btw

You can, sir.

Added

Amen.