Vesto Slipher, Christian Doppler & Albert Einstein

TheMadFool

In 1912, Vesto Slipher discovered that light from remote galaxies was redshifted, which was later interpreted as galaxies receding from the Earth. In 1922, Alexander Friedmann used Einstein field equations to provide theoretical evidence that the universe is expanding. In 1927, Georges Lemaître independently reached a similar conclusion to Friedmann on a theoretical basis, and also presented the first observational evidence for a linear relationship between distance to galaxies and their recessional velocity. — Wikipedia

The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who described the phenomenon in 1842. — Wikipedia

In 1905 Albert Einstein postulated from the outset that the speed of light in vacuum, measured by a non-accelerating observer, is independent of the motion of the source or observer. Using this and the principle of relativity as a basis he derived the special theory of relativity, in which the speed of light in vacuum c featured as a fundamental constant, also appearing in contexts unrelated to light. — Wikipedia

The Doppler effect, by itself, is unable to distinguish actual motion of the galaxies away from each other and the expansion of the universe as in the space between galaxies is increasing. Insofar as the Doppler effect is concerned the galaxies can be treated as actually moving away from each other.

The Problem:

1. From Doppler effect measurements, some galaxies are "moving" at or faster than light speed.

2. Nothing can either travel at or faster than light.

The solution:

Space is expanding. The "motion" of galaxies is a mirage.

Issue

An empirical finding that indicates motion (the Doppler effect) is being treated as a mere illusion simply to prevent the collapse of a theory (Einstein's theory of relativity).

Attempting to be funny

Next time you get pulled over by cops for speeding (speed guns use the Doppler effect) ask them how they could tell you were moving at all let alone breaking a speed limit?

Please discuss.

bongo fury

Where cars on the highway are concerned, the earth is taken as fixed, and the speeding ticket is deserved. [...]

Along with the recognition that there is no fixed distinction between fact and convention must go the recognition that nevertheless there is almost always some distinction or other between fact and convention - a transient distinction drawn by the stance adopted at the time. — Goodman, Inertia and Invention

TheMadFool

The point is that the Doppler effect is unable to tell the difference between galaxies moving and space expanding.

You can't claim that the earth is "fixed" using the Doppler effect or any other effect for that matter for the possibility remains that the earth's expansion rate and the relative motion between two objects cancel each other out - like walking on a treadmill or hamsters in a hamster wheel.

Kenosha Kid

↪TheMadFool

Hi Fool. I'm not going to get into the physics so much, more the history. But one thing to mentally separate is a particular cosmological model from the theory that generates it.

General relativity itself is consistent with a static universe, a collapsing universe, an expanding universe, whatever. The particular cosmological model Einstein was responsible for was a static universe. Far from twisting and bending to make empirical evidence fit theory, Einstein referred to the (empirically, but wrongly, derived) value for the cosmological constant he used as his "biggest blunder".

GR itself was unmolested by the expanding universe. It was just that particular model that had to be thrown out.

TheMadFool

Hi Fool. I'm not going to get into the physics so much, more the history. But one thing to mentally separate is a particular cosmological model from the theory that generates it.

[1]General relativity itself is consistent with a static universe, a collapsing universe, an expanding universe, whatever. The particular cosmological model Einstein was responsible for was a static universe. Far from twisting and bending to make empirical evidence fit theory, [2] Einstein referred to the (empirically, but wrongly, derived) value for the cosmological constant he used as his "biggest blunder".

[3]GR itself was unmolested by the expanding universe. It was just that particular model that had to be thrown out. — Kenosha Kid

[1] Isn't that a problem? If a theory is compatible with "whatever", does it even matter that there's a theory at all?

[2] I don't think it's a blunder :point: Rise, Fall, and Comeback of the Cosmological Constant.

[3] Begging the question. The Doppler shift demonstrates that some objects (galaxies to be specific) are travelling at or faster than light speed. The reason why cosmologists posited an expanding universe was precisely because they didn't want to or were afraid to go against Einstein's theory of relativity. Is this how physics is going to be done? Every time we encounter an observation that contradicts GR, we invent an new theory that proves that the observation never actually falsified GR?

We could've followed a similar protocol with Mercury's orbit when it couldn't be explained by Newtonian physics?

Kenosha Kid

↪TheMadFool

[1] Nope
[2] No offense but I'll take Einstein over yourself as an authority on relativity :D
[3] My previous post treats this.

TheMadFool

[1] Nope
[2] No offense but I'll take Einstein over yourself as an authority on relativity :D
[3] My previous post treats this — Kenosha Kid

I'm using reason, you've put your faith in authority (Einstein). I'm 100% certain Einstein would've disapproved.

Kenosha Kid

↪TheMadFool

You're not using reason. You've presented a historical inaccuracy. I was just pointing it out. If something didn't happen, there's nothing reasonable about insisting that it did.

TheMadFool

You're not using reason. — Kenosha Kid

:smile: So the rule is if you disagree with someone, that someone is being irrational. I get it!

You've presented a historical inaccuracy. — Kenosha Kid

You've missed the point, haven't you?

Kenosha Kid

↪TheMadFool

I'll just add this to the (very long) list of Mad Fool threads derailed by his own insecurities. Like I said, the historical picture you painted wasn't true. I don't really care if this has any impact on you, I'm just a stickler for facts. If you're not bothered by facts, carry on as you were. It's more for the benefit of people who might read the OP and think it was true.

TheMadFool

I'll just add this to the (very long) list of Mad Fool threads derailed by his own insecurities. Like I said, the historical picture you painted wasn't true. I don't really care if this has any impact on you, I'm just a stickler for facts. If you're not bothered by facts, carry on as you were. It's more for the benefit of people who might read the OP and think it was true. — Kenosha Kid

:rofl: You make me laugh!

TheMadFool

Thanks! :up:

Paul Gruber

The speeding ticket is an illusion. Don't pay it.

Vesto Slipher, Christian Doppler & Albert Einstein

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