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Due to conservation of momentum (also angular momentum), motion of Milky way galaxy relative to CMB produce linear momentum which must be countered by something else in the same magnitude but reversed direction.
The absolute frame of reference might be useful for navigation in type 2 or 3 civilization in Kardashev scale, just like ECEF and ECI for navigation around earth.
What that necessary?
but we still have the ether which goes by other names such as spacetime, the vacuum, etc.
I would think that Newton's 3rd for the Milky Way galaxy would be found mostly in the relationships with respect to the galaxies and galaxy clusters in the immediate neighborhood surrounding our Milky Way galaxy.
Sounds ambitious. Perhaps if our civilization lasts another twenty thousand years or so, that might become a legitimate area of research.
May I inquire as to your motivation for requiring an absolute frame of reference?
Do you have data for relative velocity of nearby galaxy wrt milky way? We could then calculate their velocities wrt cmb. So we'll know if there is a net momentum in the galactic neighborhood.
The reason why Fresnel coined the term "ether" was to make it clear that it was a thing in its own right; separate from space and permeating the vacuum.If he had just meant "space" he would have said so.
But the luminiferous ether still doesn't exist
From what I have found, the word 'ether'...
So , there is always a tacit assumption of ether in Einstein's theory.
Quote from: Hal on 12/01/2021 10:42:51So , there is always a tacit assumption of ether in Einstein's theory.Not really, no.The thing about "The ether" is it's THE ether, rather than "one of the many ethers-one for each particle in the universe" which would be a bit pointless.Again, of you choose to call your dog "The ether" then the ether exists, but it's not got anything to do with the universal luminiferous ether.
Quote from: Hal on 27/12/2020 18:40:06My arguments so far assume uniform gravitational field and hence consider only the effect of absolute motion. Gravitational time dilation isn’t a function of the uniformity of the gravitational field. It’s a function of the gravitational potential.So for instance, a clock on Earth will run faster than one sitting on Mercury despite the stronger gravitational field on Earth. A rock in freefall just above Earth will undergo greater coordinate (absolute) acceleration than a rock in freefall just above the surface of Mercury. There’s thus a stronger field just above Earth, and yet less dilation.Another example is the uniform field inside a hollow region inside something like Earth. Completely uniform field inside that hollow (per Newton’s shell theorem), and yet clocks there will be more dilated than a clock sitting on the surface.So your assumption of a uniform gravitational field doesn’t allow your clocks to keep absolute time. To do that, you’re going to need to measure absolute gravitational potential. Is Silvertooth going to similarly just assume that Earth’s surface is at maximum potential just like he assumes Earth to be (incredibly near) the exact center of the universe?Quoteand zero gravitational field around the clock. ( But any non zero constant velocity and non zero constant gravitational field should be possible, but I just prefer zero values).Since one can move upward from a clock on Earth, it is not at zero potential. Zero potential is the potential of a universe with zero mass in it. To compute the potential at Earth then, one only needs to account for all the mass of the universe. The computation isn’t all that difficult if you assume uniform mass density above a certain scale. A few minor adjustments from there to account for the planet, sun, galaxy, and not much else. But the mistake is to wave the computation away and assume it needn’t be done.How old is the universe currently? According to Earth clock, it is about 13.8 BY old, but that clock is dilated by some percentage. So what's the real age?
My arguments so far assume uniform gravitational field and hence consider only the effect of absolute motion.
and zero gravitational field around the clock. ( But any non zero constant velocity and non zero constant gravitational field should be possible, but I just prefer zero values).
There is no sensor to detect gravitational potential at a point in space, so that it can be used for automatic correction of clock rates.
There isn’t an altitude sensor either. OK, airplanes have them
There is no way to detect absolute gravitational potential, but there is a way to detect the gradient and direction.- Some of the most accurate atomic clocks have been used in an experiment where they were synchronised to each other, and then one was raised by 1 foot, and the difference in clock rates was measurable.- These accurate atomic clocks are not portable, but the next generation of optical clocks should be able to measure the gravitational gradient.As you say, this is not exactly a local measurement.So you may as well make use of other non-local measurements, like radio signals from Earth, proximity to the Sun or another planet, etc.
There’s no sensor to detect field strength at a point in space either.
So a question comes to mind as to which is the correct way of calculating the potential from the surface of a body ?
As i am then not sure if it makes a difference to an atomic clock when factoring in the suns time dilation for midday/midnight on the surface of a body like mercury/earth makes a difference in this regard.
There is no way to detect absolute gravitational potential, but there is a way to detect the gradient and direction.- Some of the most accurate atomic clocks have been used in an experiment where they were synchronised to each other, and then one was raised by 1 foot, and the difference in clock rates was measurable.
As you say, this is not exactly a local measurement.
Gravitational potential at a point in space can only be calculated, it cannot be physically sensed, whether by using potential gradient or by using non-local measurements (such as radar ).
Also suppose that an atomic clock is not transported from earth, but somehow built at a point in space. How can such a clock 'know' the gravitational potential at that point, so as to speed up accordingly ?
The atoms in the clock have no 'radars' to measure distance from earth and no 'calculators' to compute their potential.
So, if we claim to adjust a clock based on its gravitational potential which we calculated from non-local (altitude) measurements, it would be wrong and artificial.
Also imagine a clock that is affected by thousands of stars and planets.
It would be very difficult (according to GRT's gravitational potential) to keep such a clock in synch, whereas it can be corrected instantly based on gravitational field.
If this was the case, a stone thrown up would not fall back to the ground.
Quote from: gem on 15/01/2021 01:04:10So a question comes to mind as to which is the correct way of calculating the potential from the surface of a body ?They're all correct. None of the statements you posted are mutually contradictory. You're right, the potential goes up and down at various locations based on what's nearby. The potential difference between the sun's surface and Mercury is massively more than the potential difference between Mercury and the 'edge of the solar system', wherever that is.QuoteAs i am then not sure if it makes a difference to an atomic clock when factoring in the suns time dilation for midday/midnight on the surface of a body like mercury/earth makes a difference in this regard.The potential on one side of Mercury isn't the same as on the other. Ditto for Earth. 'Stationary' clocks at sea level run faster at night.
If what I posted is not mutually contradictory why do I get a different time dilation value for each scenario ?
I understand why clocks would run faster at night due to increased potential
it's the aspect of whether the suns potential is oriented at the bottom or top of the clock on the surface of mercury/earth makes a difference.
So what I am trying to nail down is which scenario of the velocity/gravitational red shift will the atomic clock show.(A) To edges of solar system; escape vel earth + escape vel sun from earth dist or(B) towards sun ; escape vel sun from earth distance - escape vel earth
I start by arguing that the failure of classical theories of light, ether theory and emission theory, wrongly led to the theory of relativity.