Today two physicists, Alexander R. H. Smith and Mehdi Ahmadi, published a paper that's causing something of a stir, and with good reason. The title of the paper says it all: "Quantum clocks observe classical and quantum time dilation."
What this means is that time dilation, a key consequence of Albert Einstein’s special theory of relativity, might be observed within the realm of the very small, the quantum, the zone that is famous for its magic-like happenings.
The thing to know is that Einstein's equations explain the behavior of the world familiar to humans. But deep down there, deep within us, or within a tree, or within the beak of a bird, his theories fall apart. At that zone, we need a completely different theory to explain reality. We call this theory quantum mechanics. The theory is not that young. It, like Einsteinian mechanics, has been around since the first decades of the 20th century. But to this day, the beginning of the third decade of the third millennium, the brightest mathematical minds in the world have yet to unite these theories of what the American philosopher William James called experience.
But why unite these worlds: the very small and, what is to us, the ordinary? The answer is simple.
Because science has made much of its progress by bringing together seemingly unrelated things. Recall that bodies observed in the sky were once thought to be totally different from the world on earth, the sub-lunar realm. But then we found that our sun is just like those stars. And that other planets had moons, and the force of gravity acted on objects up there as it did down here.
Or how about this: We once thought that Blacks were totally different from whites, but then we found they are both African apes. Science moves unity by unity. The movement towards the one feels very real. So, if we are going to make sense of experience, we must search and find its deeper unity. It must be there. The whole history of scientific development tells us it's somewhere. (At this point, I must thank the books of the theoretical physicist Lee Smolin for the unity thinking I've just expressed.)
But how does the work of Smith and Ahmadi fit into all of this? They presented a testable idea that nuclear clocks should reveal time dilation in the quantum realm. How this works is a little tricky to explain, but here it goes: In the realm of the very tiny, an object can exist in several places at once. This is called superposition. What Smith and Ahmadi propose is that in this indeterminate state, a speck of the virtual can not only be in two different places, but, according to its speed, can have two different times. The trick here is that the two different very tiny times can dilate like objects in the normal realm of conventional human experience.
For those not familiar with the concept of time dilation, Wikipedia offers this clear description of its effects on the crew in the space station drifting around and around the earth.
Time dilation explains why two working clocks will report different times after different accelerations. For example, time goes slower at the ISS, lagging approximately 0.01 seconds for every 12 earth months passed. For GPS satellites to work, they must adjust for similar bending of spacetime to coordinate properly with systems on Earth.
So, if you are on the space station for twelve months, and return to the earth, you are 0.01 seconds younger than those stuck on earth.
If the time dilation is observed at the level of quantum mechanics, this will link it to Einsteinian mechanics, and that would be a major breakthrough for the science of physics, which, as Sabine Hossenfelder pointed out in her 2018 book Lost in Math, has been making little to no progress since 1970s. But if this new idea and connection is correct, it will enhance a concept of time that I cherish: that time is more fundamental than space.
The concept was first presented in 2008 by a Greek theoretical physicist, who is now in advertising or branding, Fotini Markopoulou. The paper, "Space does not exist, so time can," is short and elegant and claims that if we reduce all of reality or experience to its essence, there is nothing but the ticking of time.
What made this concept possible is that in quantum mechanics, space can vanish altogether with what is called quantum entanglement. Drops of experience can exist nowhere. Those following Markopoulou's lead, such as Smolin, saw this quantum spacelessness as evidence of space's emergence from time. Now, if time can dilate in the realm of the very small, isn't this an indication of its primacy? Time is also here as it is out there where the big things are. And this itsy bitsy here is supposed to have, according to Einstein, no reversibility, no time. (For a vivid and even entertaining presentation of Einstein's thinking on time, read Jimena Canales' marvelous 2015 book The Physicist and the Philosopher: Einstein, Bergson, and the Debate That Changed Our Understanding of Time. I will have more to say about her book in the future posts about time and also cinema.)
If the mechanics of Einsteinian spacetime is observed in quantum mechanics, this will certainly increase the specialness of time. This possibility has made me a little happy today.