As it turns out, time is a pretty complicated thing. And I’m not talking about measuring it, or making little devices to chime out the hours, either. I’m talking about time itself. Physicists still aren’t entirely sure what time is and whether it’s absolute or relative. As Quanta Magazine reports, making sense of these two totally different ways of thinking about time is a critical missing piece to the problem of reconciling Einstein’s theory of general relativity, and quantum mechanics. Yep, this is one for the nerds. We can tell time just fine, but what is it our clocks and watches are really measuring?
The story points out that relativity and quantum mechanics describe time in different ways: “In quantum mechanics, time is universal and absolute; its steady ticks dictate the evolving entanglements between particles. But in general relativity (Albert Einstein’s theory of gravity), time is relative and dynamical, a dimension that’s inextricably interwoven with directions x, y and z into a four-dimensional ‘space-time’ fabric.” Figuring out how to reconcile this conflict may hold the answer to understanding gravity as well.
Senior writer Natalie Wolchover has been writing a series for Quanta about dark matter and the dynamics of space-time, and the latest installment is a very readable (trust me, I’ve got two humanities degrees here) look at how a new group of researchers are attempting to solve one of the biggest problems in modern physics: What is time and how does it work? The basic question she looks at is whether or not time â and gravity â are really a fundamental properties of the universe, or if they are so-called “emergent” phenomenon, arising from more basic physics.Â
In some theoretical models, things like time and gravity may arise from deeper quantum interactions â especially from quantum entanglement, a phenomenon where the state of one quantum system is directly related to another, even if the two systems are separated by a great distance.
The idea that time may not be a fundamental property of the universe â that it “emerges” from something more basic â Â may seem both unreasonable and bizarre, but we actually see emergent phenomena all the time; the color of gold, for instance, is a result of more fundamental properties of the relationship between atoms in the metal. Physicist Brian Swingle, also writing for Quanta, explains, “Consider a lump of gold. It is comprised of many billions of atoms, all of which interact with one another. From those interactions emerge the various classical properties of the metal, such as color, strength or conductivity.”
As abstract as all this sounds there is actually some experimental evidence that it might be true. Very dense stuff and the math is definitely off-limits to non-specialists, but the article, if you’ve a taste for this sort of thing, is highly thought provoking.
Check out the full story at Quanta Magazine online.Â Lead image, an Andrewes Longitude Dial sundial; to find out more, check out our video story here.