Physics is full of paradoxes , but one of the most famous is the contradiction in terms between quantum mechanics and Einstein ’s theory of general relativity . At last , a new bent of unbelievable experiments may reconcile the two systems .
double viaPatrick Edwin Moran
Over at Quanta , Natalie Wolchoverintroduces the problem :
It starts like a textbook physics experimentation , with a ball confiscate to a spring . If a photon strikes the ball , the shock sets it oscillating very mildly . But there ’s a apprehension . Before reach out the ball , the photon encounters a half - silvered mirror , which reflects half of the lightness that strikes it and allows the other half to slide by through .
What materialize next depends on which of two passing well - tested but contradictory theories is correct : quantum car-mechanic or Einstein ’s theory of general theory of relativity ; these identify the small- and turgid - scale properties of the creation , respectively .
In a strange quantum mechanically skillful force called “ superposition , ” the photon at the same time passes through and muse backward off the mirror ; it then both strikes and does n’t strike the ball . If quantum mechanics works at the macroscopic level , then the bollock will both start oscillate and stay still , entering a superposition of the two states . Because the ball has mass , its gravitational athletic field will also split into a superposition .
But according to worldwide relativity , solemnity warps quad and clock time around the ball . The theory can not tolerate space and prison term warping in two different ways , which could destabilize the superposition , forcing the ball to dramatise one state or the other .
Knowing what happens to the ball could facilitate physicist address the battle between quantum mechanism and general Einstein’s theory of relativity . But such experiments have long been considered unfeasible : Only photon - size of it entities can be put in quantum superpositions , and only ball - size of it objects have detectable gravitational field . Quantum mechanics and general relativity reign in disparate domains , and they seem to meet only in enormously thick , quantum - size black holes . In the science lab , as the physicistFreeman Dyson wrotein 2004 , “ any differences between their predictions are physically undetectable . ”
In the retiring two age , that wide carry view has begun to alter . With the supporter of new preciseness instruments and clever approach for indirectly probing imperceptible effect , experimentalists are now take footstep toward investigating the interface between quantum mechanic and universal relativity theory in tests like the one with the photon and the ball . The new experimental possibilities are regenerate the 80 - yr - old quest for a theory of quantum gravitation .
“ The crowing single problem of all of physics is how to patch up gravity and quantum car-mechanic , ” saidPhilip Stamp , a theoretical physicist at the University of British Columbia . “ All of a sudden , it ’s clear there is a target area . ”
idealogue are thinking through how the experiments might play out , and what each outcome would mean for a more complete hypothesis merging quantum mechanics and general Einstein’s theory of relativity . “ Neither of them has ever fail , ” Stamp said . “ They ’re incompatible . If experimentation can get to grips with that conflict , that ’s a big muckle . ”
Want to find out about the experiments — some of which will be in space — that could lead in a merging of quantum mechanic and gravity?Read the whole essay over at Quanta .
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