Earths Absolute Velocity

[Tormod]

No. Only paying sponsors will be able to lose the adverts...soon. :)

 

But there is a setting somewhere in your user cp where you can set the number of topics per page, I think.

 

I was wrong. I find no such setting. C1ay may just be lucky. :xx:

[C1ay]

Maybe it's a resolution thing. This topic is now on page 3 for me and has ads at the top, down the side and across the bottom....

[C1ay]

But there is a setting somewhere in your user cp where you can set the number of topics per page, I think.

Found it. Under the User CP>>Edit Options>> Thread Display Options you can adjust the number of posts to display per page. Mine is set to 40. Unfortunately that's as high as it goes :xx:

[Tormod]

Strange. I don't have that option.

[Harzburgite]

Well, that is not so much an answer as an assertion that no answer is possible..

With respect, it is an excellent answer, inasmuch as it accurately reflects our understanding of the truth. Did you want me to lie?

Your suggestion of using variations in Cosmic Background Radiation is interesting, but, I think, ultimately flawed. Since every point in the Universe was the centre from which expansion began, we should expect that such analysis would reveal we are at the centre of the Universe. This would be good news for those who believe man is special, but does nothing to define absolute velocity: it does not exist.

[BlameTheEx]

With respect, it is an excellent answer, inasmuch as it accurately reflects our understanding of the truth. Did you want me to lie?

Your suggestion of using variations in Cosmic Background Radiation is interesting, but, I think, ultimately flawed. Since every point in the Universe was the centre from which expansion began, we should expect that such analysis would reveal we are at the centre of the Universe. This would be good news for those who believe man is special, but does nothing to define absolute velocity: it does not exist.

Er, no.

 

I was at some pains to point out that this method gives a local absolute zero velocity, not a universal one. If there is any validity to the theory each location has a different absolute zero velocity. It would be as if the absolute velocity of distant locations is subject to the hubble constant.

 

I don't want you to lie. It would be nice if you didn't patronise ether. Sigh.

[Jay-qu]

i dont understand why light 'red' and 'blue' shifts over long distances when the observer is moving away or toward an object. I see how it works with the example of an ambulance or police car with sirens going past, but i thought light would be immune to this effect because arent you supposed to be able to measure light at the same velocity no matter how fast or slow you yourself are traveling. So how is it the the wavelength changes? is it to do with the frequency changing in proportion so that v remains c?

[Boerseun]

i dont understand why light 'red' and 'blue' shifts over long distances when the observer is moving away or toward an object. I see how it works with the example of an ambulance or police car with sirens going past, but i thought light would be immune to this effect because arent you supposed to be able to measure light at the same velocity no matter how fast or slow you yourself are traveling. So how is it the the wavelength changes? is it to do with the frequency changing in proportion so that v remains c?

Yes.

 

The wavelength of light emitted by an object moving towards you, decreases - the "peaks" and "troughs" pile up so that as far as you're concerned, v remains c. Same with an object moving away from you, but the wavelength increases, while v remains c for both you and the object - although light emitted by you will seem to the object to be red/blue shifting, depending on wether the object is approaching or departing.

[Boerseun]

...by the way, the Doppler effect you refer to in terms of police sirens and ambulances operate in the same way. The speed of sound stays the same, wether the object is approaching or departing. It's just the wavelength the piles up or stretches out.

That's how a sonic boom works - the waves pile up in front of the aircraft untill the plane is moving at the same speed as the compressed wave in front of it. A very loose analogy for this would be the bow-wave of a ship, where the ship is moving faster than the wave can propagate.

[Jay-qu]

yeah yeah i understand all that, except how this comes about... because if the wave stays at c no matter your velocity how does the frequency and wavelength?

[GAHD]

Blueshifts and redshifts, Wiki might help you a bit with the explanations.

[Jay-qu]

yeah thats better thanks - the expanding space actually streches the light ray... interesting

[Jay-qu]

new idea, could cosmic background radiation be used to determine velocity - ie by measuring the radiations blue/red shifts in different directions... and if you could measure the velocity what would it be relative to?

[Qfwfq]

CMB anisotropy has been observed JQ, it's a matter of interpreting it. AFAIK it isn't currently considered to be a detection of absolute motion.

 

A very loose analogy for this would be the bow-wave of a ship, where the ship is moving faster than the wave can propagate.

No Boerseun, not a "very loose analogy" at all, it's the exact same thing! :eek2: So is Cherenkov light.

[Turtle]

___I say no absolute velocity because part of that velocity is imparted by Earth's rotation & Earth's rotation is steadily slowing. By the time you measure it is changed so it is only a relative measure, not absolute. :doh:

[HydrogenBond]

The fact that laws of physics are the same in all references appear to imply a fixed reference for laws of physics that is independant of velocity. Only the measured mass. distance, time, output is the result of the relative motion. Light speed is fixed with respect to this reference.

 

The comment about Andromeda and the Milky Way galaxy approaching each other is interesting; it is an example of a place within the universe that is contracting.

[maddog]

if it where possible to pinpoint an exact position in space ( but im not sure if this is possible because of expansion) could you then calculate earths net velocity relative to this 'stationary' point? if so has this been attempted?

Velocity by definition today is "Relative to some reference" as Einstein overturned the

Absolute Velocity of Newton and has since gone into disfavor.

 

Basically all things are in motion. So where you find the "Absolute Rest" point to

measure "Absolute Velocity".

 

maddog