Tag Archives | Space-Time

Perfectly accurate clocks turn out to be impossible

Clock face
Faculty of Physics University of Warsaw via EurekAlert:

Can the passage of time be measured precisely, always and everywhere? The answer will upset many watchmakers. A team of physicists from the universities of Warsaw and Nottingham have just shown that when we are dealing with very large accelerations, no clock will actually be able to show the real passage of time, known as “proper time”.

The ideal clock is merely a convenient fiction, as theorists from the University of Warsaw (UW) and University of Nottingham (UN) have shown. In a study published in the journal Classical and Quantum Gravity they demonstrate that in systems moving with enormous accelerations, building a clock that would precisely measure the passage of time is impossible for fundamental reasons.

“In both theories of relativity, special and general, it is tacitly assumed that it is always possible to construct an ideal clock – one that will accurately measure the time elapsed in the system, regardless of whether the system is at rest, moving at a uniform speed, or accelerating.

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New “Jewel” of Quantum Field Theory Suggests Space-Time Might Be Totally Illusory

A new geometric understanding of elementary particle interactions that might undo the preeminence of space-time.

Generally speaking, elegance and simplicity are markers of finding the theoretical path to a grander truth, while messiness or complication is the signifier of having an incomplete or flawed understanding of the issues at hand.  Though there are many who would argue against applying this idealization of “beauty” in the sciences, it should be remembered that our perception of beauty was classically quantified and rationalized (think phi and golden ratios) well before anything as arcane as particle physics could exist.

With this in mind, observe the practical, beautiful simplicity of the “amlituhedron” quantum jewel.  A theoretical breakthrough coming out of Princeton, this geometrical understanding of particle interactions has made previously uncomputable equations solvable with good old pencil and paper.  And if that isn’t tantalizing enough, the math suggests that locality, unitary, dimension, and even space-time itself could be flawed as basic assumptions for the interactions of elementary particles.… Read the rest

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Space-Time Cloak Possible, Could It Make Events Disappear Too?

4467116919_603041818fCould an entire bank heist take place at an open bank with no one seeing it? The National Geographic reports:
It's no illusion: Science has found a way to make not just objects but entire events disappear, experts say. According to new research by British physicists, it's theoretically possible to create a material that can hide an entire bank heist from human eyes and surveillance cameras. "The concepts are basically quite simple," said Paul Kinsler, a physicist at Imperial College London, who created the idea with colleagues Martin McCall and Alberto Favaro. Unlike invisibility cloaks — some of which have been made to work at very small scales — the event cloak would do more than bend light around an object. Instead this cloak would use special materials filled with metallic arrays designed to adjust the speed of light passing through.
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