Sorry, folks. I found the refutation of this absolute question some way back in another thread.
Spin can be observed relative to the 'fixed' star background. If spin of a planet is absolute, then the whole starry firmament must re rotating individually around every planet and each moon.
I know which scenario I will choose.
Atlan0101
I only skimmed this thread, but two words and two forces seem to be missing entirely from it. Centripetal force and centrifugal force.
Also, 'c' is a constant, not an absolute. Don't confuse one with the other.
Centrifugal force - Wiki:
The Earth constitutes a rotating reference frame because it rotates once every 23 hours and 56 minutes around its axis. Because the rotation is slow, the fictitious forces it produces are often small, and in everyday situations can generally be neglected. Even in calculations requiring high precision, the centrifugal force is generally not explicitly included, but rather lumped in with the gravitational force: the strength and direction of the local "gravity" at any point on the Earth's surface is actually a combination of gravitational and centrifugal forces.
The Earth, of course, is rotating relative to the 'fixed stars' background, evidenced by our experiencing day and night.
According to Einstein-Mach, spin is relative.
Vide The meaning of absolute:
. . . . . . , the Einstein/Mach viewpoint holds that rotation is not relative to space, but rather is defined relative to the matter in the universe. If this viewpoint is correct, you would never see any precession of the pendulums because the bulk of the matter in this experimental universe is the planet itself, so it basically defines the frame of zero rotation.
Pogo said:
Given enough time in the life of our solar system, the tidal drag of the sun on the earth will eventually cause the earth to become tidally locked or in some sort of resonance. So would each of the planets on out.
I would assume the Moon would be the fly in the ointment for any solar tidal-lock with Earth. The Moon goes around once every month, perhaps just over a month in a billion years, so how could the weaker grav field of the Sun overcome that dragging force?
The observer on the Earth's surface could carefully measure the distance of each latitude line and determine that the Earth is an oblate spheroid and can determine that it was caused by spin, and even roughly calculate the spin.
There is also the Coriolis Effect, and how a pendulum swings.
Newtonian physics, to conserve angular momentum, it wouldn't make any difference whether there is an observer or not, the spin is still the same.
This goes back, however, to the argument for centripetal force. Mach argued, IIRC, that it is all the matter in the universe that is required for this to exist; remove all the matter, except Earth, and it goes away. It's hard to agree with it as we are quite comfortable calculating the gravitational attraction between any two chunks of matter. Cavendish(?) measured that force from a nearby mountain.
This is sorta like the age-old question 'If a tree falls in the woods with no one around, does it make a noise?' It depends of your notion of sound . . . is it the vibration of molecules in the air or is it the reception of vibrating molecules on the eardrum?
I've never understood why this is so popular. BHs aren't hypothetical even though we can't, by definition, observe them directly. Indirect and circumstantial evidence is enough to qualify as enough compelling evidence to not even ask the question in a scientific sense.
It's like a question that plays on the idea that science can't prove anything. Proofs may be for mathematics, but we should all accept scientific claims once the evidence is compelling, or greater.
What am I missing?
Helio, I don't if this helps, but you may recall that there was some discussion based on whether the Newtonian or Einstein-Mach viewpoint was correct. But this was in relation to a totally fictitious situation where the whole Universe was assumed to be ignored and the Earth alone considered as spinning. Hardly a worthwhile exercise. However, even if one wants to play imaginary philosophy, then it seems that Einstein-Mach came out on top anyway.
P.S. Once you put back the 'real Universe', then Earth is seen to spin against the background of the 'fixed stars'.
Atlan, "Also, 'c' is a constant, not an absolute. Don't confuse one with the other."
Thank you for confirming that your position is that 'c' is not absolute.
I am coming to the opinion opinion that there are some factors which do not exist in reality, but are approached (perhaps closely) asymptotically. 0 deg K is an example.
IMO, it is fine to call 'c' an absolute but with the caveat that it is applicable to one's own inertial frame. It is so absolute, in fact, that we no longer have a reference stick to define a meter. The length of one meter is based on 'c', because it is an absolute value for a "stationary" reference frame.
Helio, that is why I chose deg K for my example.
Yes, and did you know that the units are in "kelvins", not "Kelvins"?
There is an article today about an exoplanet that has only about twice the temperature of Earth, using Centigrade. But, in kelvins, it is really only about 10% hotter. Significant difference, which is why I prefer kelvins, except on my home thermostat.
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Helio, I find this really weird. Both Fahrenheit (named after a person) and Celsius are capitalised, and so are their abbreviations, F and C. Yet kelvins are not, despite being named after a person. That is insulting.
To make it even worse, there is k representing the Boltzmann constant, so both this and temperature, closely related in thermodynamics, are represented by k.
Who on Earth came up with this?
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"Caveat": Large Hadron Collider (closed system) (closing system).
Opposed: Infinity (open system) (opening system).
Universe.
Multiverse.
How broad is the ocean of the universes?
How deep is the ocean of the universes?
You can't coordinate the breadth. It's too broad.
You can't coordinate the depth. It's too deep.
You might think you can coordinate your own small bubble of it, relatively speaking that is, but not really.
Not trying to be derogatory or facetious, but give me the "stationary reference frame" for the principle of uncertainty writ large. One in which you the observer cannot tell precisely a point of position. Or, one in which you the observer cannot tell precisely a plane of velocity or momentum. (** you are absolutely right for finite-foreground "local", but I wanted to insert the opposing qualification for infinite-background "non-local". After all, regardless of the closed-minded-only who insist that only "closed system" exists, that there is no such thing as an existence of "open system", for one to exist the other must exist. And if one is subordinate to the other, then there are two opposing subordinates in two opposing realms. **).
You're "absolute value for a 'stationary' reference frame" is [coordinately] correct within any one of an infinity of four-dimensional boxes. You would have a big problem between the boxes though. That "absolute value" then loses all its meaning. The speed of light constant will measure its constant within them all, from all points of each and every box in (closed systemically), but loses all meaning between boxes (open systemically), For example: Is that distant object from you, observed to be that distance from you, in fact that distance from you? Is it even there? Is it even that object? Was it ever there where you observe it? And was it ever that object you observe it to be? Did it ever have the "absolute values" you (you in general, that is) observe it to have and give it? Though, once again, "the length of one meter is based on 'c'", is based on a unity of physics, and would be one meter in length within any of an infinity of four-dimensional boxes.
There have been representative illustrations of entire scenes closing up to a line, a bubble contracting into extremities of contraction, then to a point, then disappearing inside some other scene. A universe, still existing in own right locally, having disappeared -- to all intents and purposes, leaving the other "local" universe in its place. Two universes occupying the same space at the same time, ** and/or ** but not the same space and not at the same time. Quantum weirdness? UFO-ology? Breakdown of relativity? The ocean seas of space are mighty, mighty, deep in ocean seas as well as mighty, mighty, broad in them.
Post #29:
'Given enough time in the life of our solar system, the tidal drag of the sun on the earth will eventually cause the earth to become tidally locked or in some sort of resonance. So would each of the planets on out. '
'I would assume the Moon would be the fly in the ointment for any solar tidal-lock with Earth. The Moon goes around once every month, perhaps just over a month in a billion years, so how could the weaker grav field of the Sun overcome that dragging force? '
First, the tide as a result of the sun's gravity is a bit less than that of the moon (https://en.wikipedia.org/wiki/Tide). I had read somewhere a few years ago (maybe Sky and Telescope) that one can calculate that the earth does, in fact, raise a tiny tide on the sun, so do the other planets. Just as the lunar tide cause drag on the earth's rotation and transfer of angular momentum to the moon raising its orbital semimajor axis, the earth's semimajor axis has also increased. They calculated that it may have raised earth's orbit by maybe 6 inches (15 cm) over the course of the solar system's existence, certainly not a measurable amount. So, the moon's rotation has slowed and locked to the earth, and the earth's rotation is dragging the moon along and transferring angular momentum to the moon's orbit raising bit by bit and will eventually cause the earth's rotation to lock with the moon's orbit. Similarly, the earth's rotation is subject to a bit of drag with the sun slowing down the earth's rotation. Since the earth's rotation will continue to slow down, it's now trying to slow down the moon's orbit, hence the moon will begin to decrease its semimajor axis until it reaches the earth's Roche limit, then will break up and produce a Saturn-like ring system, but made of rock instead of ice. This was actually a theory in an astronomy textbook published in about 1949. But, the sun's life as a normal star will not last long enough for this to happen, the red giant phase will happen way before this can occur.
Post 36:
'Helio, I find this really weird. Both Fahrenheit (named after a person) and Celsius are capitalised, and so are their abbreviations, F and C. Yet kelvins are not, despite being named after a person. That is insulting. '
Yeah, I never quite understood that °C, ºF both get the °, but the K does not. In Wikipedia, Kelvin is capitalized, I had not seen where K is k. But, also, °R (Rankine, which no one uses anymore) still gets the ° and is capitalized. Why is Kelvin different?
According to Wikipedia (https://en.wikipedia.org/wiki/Kelvin), the General Conference on Weights and Measure opted to remove the ° from the K. But, why K is so special as to not need the ° was not explained.
"But, why K is so special as to not need the ° was not explained."
I don't know, but it may have something to do with K being "absolute".
My old physics teacher made a big thing about (for example) degrees Centigrade and Centigrade degrees, 10° Centigrade is a temperature, whereas 10 Centigrade degrees is a temperature difference. If anyone said "heat the water through 10° Centigrade" he would hit the roof. Likewise is someone said (much less likely) "water boils at 100 Centigrade degrees).
Perhaps 10 Kelvin degrees being the same as 10 Centigrade degrees has something to do with it?
Sorry that I missed this post...
...Similarly, the earth's rotation is subject to a bit of drag with the sun slowing down the earth's rotation. Since the earth's rotation will continue to slow down, it's now trying to slow down the moon's orbit, hence the moon will begin to decrease its semimajor axis until it reaches the earth's Roche limit, then will break up and produce a Saturn-like ring system, but made of rock instead of ice.
Yes, though we are talking a very long time before that could happen. Perhaps other astro events will have an....impact on this model.
Once the main body rotates slower than the orbit, the orbiting body will begin to fall. But they could reach a balance if the cause of the slower rotation is altered. This likely won't be the case with the Sun's action on Earth's rotation, though the Sun will spin slower, no doubt, as it expands.
Yes, I think you found the crux.
I rarely like to tread into grammar, but what the heck....
We treat "degrees" in "degrees Centitgrade" as an adjective. But you stated it more accurately I think with "Centrigrade degrees". "Centigrade" may be the modifier to "degrees".
But "kelvin" is a unit and is not a modifier, just like "meter" or "watt". It doesn't come in degrees because it is a unique and absolute scale. Anyone can create their own temperature scale by introducing their own modifier term followed by "degree". 2000 "degrees Helio" (ie "Helio degrees") might represent the color red. [BTW, the math is simple to make your own scale.]
Here is a discussion that seems to offer a reasonable explanation.
BTW, if someone knows which one of those words I didn't need to put into quotes, I would like to know to avoid using them, as I don't like to use them.
Helio, "BTW, if someone knows which one of those words I didn't need to put into quotes, I would like to know to avoid using them, as I don't like to use them."
I can't see anything actually wrong with them, although I would probably leave them out for actual units like metre or watt. (Here I italicize to draw attention, not to suggest someone is saying (writing) them.
"degrees Helio" (ie "Helio degrees")
Quotes are OK here, because you are discussing an abstract or concept. Metres and watts are existing units - hence no quotes. I might italicize, but I don't know any rules. [I have been quiet/inactive this week as our old house is being rewired, with power on/off etcetera. Fortunately now completed.
But, OH! degrees Helio are not the same as Helio degrees!
2000 degrees helio (H?) is a temperature. 2000 Helio degrees is a number of degrees on the Helio scale, which might be 2000 H degrees above or below 7000 degrees Helio. It is a number of degrees, not a temperature.
I can't see anything actually wrong with them, although I would probably leave them out for actual units like metre or watt. (Here I italicize to draw attention, not to suggest someone is saying (writing) them.[
Yes, that makes sense.
Agreed. I was trying to squeeze more juice out of its use as a modifier, and not the apt distinction you note.
Why do you think OP asked such a stupid question. Isn't it obvious?
Isn't it obvious?
Absolutely not! . [ nice set-up ]
Is anyone arguing with this?
The only way out I can imagine is the (imho) specious argument about doing away with the whole Universe except the Earth . . . . . . . . . some feat"
. . . . . . . . . . . . and then argue with Einstein-Mach.
The problem is that there is no known test demonstrating detectable spin if there is no matter in the universe.
If some sort of anti-gravity device ever comes around that can cancel all the gravity around an object, then we should be able to do that test, but this is not science, but imagination.
Helio, "The problem is that there is no known test demonstrating detectable spin if there is no matter in the universe."
I, personally, do not care a flying M class asteroid what can be postulated if there is no (other) matter in the Universe. It is unreal, and always, now and forever will be unreal. Amen. Aaaaaa-aaaa-men.
Science should (imho) not be treading where no observations can nor ever will be able to be made. This is the realm of the . . . . . . . . . worst times in our history . . . . . . . . . when Galileo and . . . . . . . . .
(I am not allowed to fill in the blanks)
I am 100% behind science and against any sort of evil intimidation . . . . . . in the name of . . . . . . . . . but this argument about spin (as in rotation about an axis) ( ) is, imho, nothing to do with science. It is (imho) mathematical mismanipulation of the worst kind. I do occasionally (not more than 10 times a day) dally with some philosophical questions, but I accept your viewpoint that this is not science. And if 'science' descends into invoking anti-gravity devices then, sadly, imho, it is no better than Popeye the cartoon character
Science should (imho) not be treading where no observations can nor ever will be able to be made.
Agreed, though I don't mind mathematical abstracts and scientific suppositions. The emphasis I sense is needed -- many may disagree on such emphasis -- in general is that we need to keep pushing science away from being merged with "isms"; scientism is not a good thing.
And if 'science' descends into invoking anti-gravity devices then, sadly, imho, it is no better than Popeye the cartoon character
We will disagree, but only partly -- wild ideas must be taken separate from hard science. It is part of science, none the less, to consider what may or may not result when one material thing is added or taken away. Your chemistry background excels at this sort of thing.
What would happen if external gravity is removed? Is this an example of something to be taken "in principle", or perhaps not? I argue it is a fair example, and not too uncommon, IMO.
The bucket whirling scenario is a legitimate scientific debate and it's such scientific ideas, even if purely suppositional, that may lead to advancements in science.
Einstein's asking whether or not standing in an elevator in space represented a difference between acceleration and gravity gave us the greatest theory of all time -- GR.