![]() Quantum field theory can’t say what objects lie beyond spacetime, but it can veto bad hunches. The physics of spacetime must arise, precisely, as a special case of our new theory. Any theory we propose must project onto spacetime. We must propose a new theory, with new structures and processes beyond spacetime. But they cannot tell us what is fundamental, what lies beyond spacetime. So quantum field theory and gravity together warn us that spacetime is not fundamental. Thus our device can only have finite degrees of freedom and finite resolution. The total matter within our reach is finite. We may see them, but we can never reach them. ![]() Most galaxies are receding from us faster than light. Well, why not take the device out of the lab? With endless room, can’t we make the device arbitrarily precise without creating black holes? Nice idea, but it has a problem: Our universe is expanding. SUGGESTED VIEWING Time, Space and Being With Hilary Lawson, Michela Massimi, Julian Barbour, Huw Price So, as I upgrade my lab to make my device more precise, its mass grows to the point where gravity again creates a black hole, destroying my lab and measurement. Therefore a more precise measurement requires a device with more degrees of freedom, and thus more mass. Moreover, quantum theory tells us that a measuring device is a quantum system, subject to quantum uncertainties. When the resolution approaches the Planck scale, the density of mass grows so large that gravity spoils the party, creates a black hole, and destroys our measurement. Thus, as we increase resolution we pack more energy, and therefore more mass, into less space. Einstein tells us, in a famous equation, that energy and mass are the same. Quantum theory tells us that as wavelengths shrink their energy grows. Why do physicists say that spacetime is doomed? Because, they argue, it has no operational meaning below the “Planck scale,” roughly 10 -33 centimeters and 10 -43 seconds.įor instance, to measure the position of a subatomic particle with higher resolution, we must use radiation of smaller wavelength. He quoted prominent physicists who agreed. David Gross, a 2004 Nobel Laureate in physics, predicted in his tribute to Einstein that spacetime is “doomed,” that it is not fundamental. In 2005 physicists celebrated the centenary of spacetime. It is the foundation for the edifice of science and the spin-offs of technology. ![]() The quantum fields of the acclaimed Standard Model of particle physics are defined over spacetime. We feel its curves as gravity and see its singularities as black holes. That union, that fundamental and independent reality, is spacetime. As Hermann Minkowski announced in 1908: “Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.” ĭavid Gross, a 2004 Nobel Laureate in physics, predicted in his tribute to Einstein that spacetime is “doomed”, that it is not fundamental. With Albert Einstein, and his 1905 theory of special relativity, they are fundamental and united. With Isaac Newton they were fundamental and distinct. It is no wonder then that, for centuries, science has taken space and time as fundamental. SUGGESTED READING Einstein and why the block universe is a mistake By Dean Buonomano My confinement within space and time appears complete. ![]() I may as well try to imagine a new color I’ve never seen before. If I challenge myself to imagine something-anything-outside of space or beyond time, I’m stymied. My immersion is total: space and time are my perceptual reality, yes, but also my conceptual cage. When I gaze at countless stars on a crisp night, I feel myself shrink to a mere speck that is trekking through space and coasting through time. I feel myself to be immersed in space and time. Who am I? If I glance in a mirror, I appear as a body, as one object among scores in space and time. So, what lies beyond spacetime? We, ourselves, might be part of the answer, writes Donald D. But modern physics, from quantum field theory to gravity, now suggests spacetime is doomed. Since at least Einstein we have seen spacetime as fundamental.
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