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The results of the experiments enabled the researchers to set an upper limit of 10-7 on the boson-to-fermion gravitational constant ratio. The researchers also searched for a dependence of gravity acceleration of strontium-87 isotope on the spin direction, but found no evidence for it.
"There are theoretical models predicting that spin and gravity should couple; that is, depending on its spin a particle should behave in different ways in a gravitational field," Tino said. "We found no evidence for that. Since we compared an atom with spin with one without spin, this is a rather stringent test. Also, in our experiment one atom is a boson and the other is a fermion and, again, we found no difference in their behavior in a gravitational field."
Read more at: phys.org...
originally posted by: ImaFungi
a reply to: mbkennel
The only reason a particle (and its spin, referring to its actual physical rotation?,or I know spin refers to the degrees of rotation before the particle is identical to its starting position, so do particles with different spin, are they spinning at all physically, rotating?)
originally posted by: mbkennel
The Standard Model is right and we've seen no deviation, and general relativity is right and we haven't seen any deviation, and they still don't play nice together and we don't know how to make them do that in any way that seems to be experimentally verified or verifiable.
originally posted by: ImaFungi
So, my questions are the main obvious intuitive questions to ask about such a thing, and so in one corner there is the self consistent QM which ignores the existence of gravity, and the other hand is general relativity which ignore existence of QM, and since Einsteins death bed and prior, have there been any narrowing down towards consensus as to what the reality of the situation appears to be?
From what I have been explained about it is that QM (or GR cant remember which), the pesky thing about it deals with all sorts of infinities so they have to create 'cut offs', to make the equations check out, and with the semi arbitrary cut offs, gravity is compatible with QM up until a certain point, the point of approaching ever higher levels of energy, where once again there enter problems with infinities I guess and the lack of checking out.
Now, the first thing I would think to ask is; musn't it be something about QM sitting down to write its self consistent equations and ignoring gravity that makes it difficult to once QM equations are tidy and equal to then try and shove gravity in, isnt it no wonder there is a problem?
So musn't the problem be that in the QM equations there is a region of energy/mass that is being neglected and wrongfully appropriated to other constituents that makes the equations and prediction experiments work, but admitting to leaving out values of gravity it is understood that the equation, something about the values must be 'off', in the sense of their labels.
The second thing I would say, is could it be that when approaching high enough energies with materials the reasons the equations break down, and this might be related to black holes because thats what happens at those energies right (?)
originally posted by: Dolour
weve developed string theory, and put ALL our money on that one horse, sums it up pretty much i think.
unfortunatly QM and field theory dont seem to be compatible at all.
yet we do NOT look out for a flaw in the equation, but squeeze and stretch it, add arbitrary value etc until it "somehow" aproximates.
it dosesent really make grav. any more compatible, but the described cut offs are made to obtain results one can work with, and herein lies one of the initial problems.
while we do have to make cutoffs for practical reasons, theory doesent account for those values being cutoff.
every pupil is told that a "coffecup full of vacuum could evaporate all of earths oceans" this tremendous ammount of energy is basically completely ignored.
the problem is pretty deep rooted really.
we have NO clue at all what gravity really is, and describing something mathematical that you dont understand is more a game of chance.
we know that energy packed into an area of space causes gravity. it doesent seem to matter what manifestation this energy has, its total contributes to its "mass total" and therefore its gravitational pull.
strong force is a good example. some binding-energy that makes up the largest part of a systems total energy(with no evidence other that nuclei stick togeather btw, again a practical, arbitrary thing that could be caused by whoknowswhat).
the underlying mechanic however is a complete mystery, and we cannot describe space-curvature in descrete terms, or even pinpoint wth is curving it to begin with.
regarding your unanswered question:
planck units are derived from physical constants, and physical constants alone (thats actually what makes them so important :p).
a planck lenght is the smallest possible wavelenght, a planck time is the time a photon needs to travel a planck lenght.
there is no such thing as a planck propability, and yes its very well within the realm of possibility that einstein was right when he doubted that "the old one would roll dice".
im not so sure about gravity being the cause of propability, but i too think theres an underlying mechanic we yet just dont understand and consider it "random".