Science
Related: About this forumPhysicists investigate the structure of time, with implications for quantum mechanics and philosophy
From phys.org:
Although in theory it may seem possible to divide time up into infinitely tiny intervals, the smallest physically meaningful interval of time is widely considered to be the Planck time, which is approximately 10-43 seconds. This ultimate limit means that it is not possible for two events to be separated by a time smaller than this.
But now in a new paper, physicists have proposed that the shortest physically meaningful length of time may actually be several orders of magnitude longer than the Planck time. In addition, the physicists have demonstrated that the existence of such a minimum time alters the basic equations of quantum mechanics, and as quantum mechanics describes all physical systems at a very small scale, this would change the description of all quantum mechanical systems.
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Nevertheless, there is a great deal of theoretical support for the existence of the Planck time from various approaches to quantum gravity, such as string theory, loop quantum gravity, and perturbative quantum gravity. Almost all of these approaches suggest that it is not possible to measure a length shorter than the Planck length, and by extension not possible to measure a time shorter than the Planck time, since the Planck time is defined as the time it takes light to travel a single unit of the Planck length in a vacuum.
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"The physical universe is really like a movie/motion picture, in which a series of still images shown on a screen creates the illusion of moving images," Faizal said. "Thus, if this view is taken seriously, then our conscious precipitation of physical reality based on continuous motion becomes an illusion produced by a discrete underlying mathematical structure."
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The Velveteen Ocelot
(115,734 posts)EdwardBernays
(3,343 posts)of the notion that there's no such thing as a perfect circle...
virtualobserver
(8,760 posts)I could spend the rest of my life at that website.
HassleCat
(6,409 posts)The tale of Achilles and the tortoise shows that there is no least unit of time. The quote from Faizal addresses this, as well as the opinion of Alfred North Whitehead (I think) who declared, "Time is not a motion picture." Reality is reality, and not subject to being bounded by the artificial construct of mathematics. Sorry, number geeks.
Jim__
(14,077 posts)Last edited Tue Feb 2, 2016, 09:52 AM - Edit history (1)
Zeno's paradoxes are based on our perception of motion as continuous. Zeno shows that this involves paradox whether we consider time to be continuous or discrete or space to be continuous or discrete. The arrow paradox is where Zeno shows that if time is discrete, motion is impossible.
Faizal, of course, is a co-author of the paper that is proposing that time is discrete. So, he believes that motion is discontinuous, and our perception of motion pictures indicates that we can perceive discontinuous motion as continuous. Yes, of course, reality is reality; but reality is not necessarily as we perceive it to be.
As far as artificial mathematical constructs go, Faizal is a professor of physics and astronomy at the University of Waterloo. The article also suggests some ways that the idea may be tested.
Time is not a motion picture seems tautological. If Whitehead actually said this, I'd like to see the context.
HassleCat
(6,409 posts)If you give the tortoise a one Planck length head start, Achilles can never catch up because, by the time Achilles has covered the distance of one Planck length, the tortoise will have progressed some fraction of a Planck length ahead, and so on. Yes, I know there is no such thing as a fraction of a Planck length, but that's the point of the debate.
Whitehead was just expressing his opinion that time is continuous, not segmented. It rolls along, and does not jump from one frame to the next, no matter how many frames per second the camera records
Jim__
(14,077 posts)... that there is no minimal distance.
Zeno knows that if you watch the race, you see Achilles catch the tortoise. But, if you assume that space is continuous - i.e. there is no minimal distance - then Achilles can't catch the tortoise. This supports his argument that all motion is an illusion. The natural counter-argument is to assume that there is some minimal distance; but Zeno has other paradoxes to counter that.
cantbeserious
(13,039 posts)eom