Does time exist? The answer to this question may seem obvious: of course it exists! Just look at a calendar or a clock. But advances in physics suggest that the nonexistence of time is an open possibility that we should take seriously. How is this possible and what would it mean? It will take time for us to explain ourselves, but don’t worry: even if time does not exist, our lives will go on as usual.
A crisis of physics
Physics is in crisis. For about a century, we have explained the universe with two very successful physical theories: general relativity and quantum mechanics.
Quantum mechanics describes how things work in the incredibly small world of particles and the interactions between them. General relativity describes the big picture of gravity and the motion of objects. The two theories work very well on their own, but they are believed to be in conflict. Although the exact nature of the conflict is disputed, scientists generally agree that the two theories should be replaced by a new, more general one.
Physicists want to come up with a theory of quantum gravity that replace to general relativity and quantum mechanics, but which enjoys the extraordinary success of both. Such a theory would explain how the big picture of gravity works on the miniature scale of particles.
time in quantum gravity
It turns out that constructing a theory of quantum gravity is extraordinarily difficult. An attempt to overcome the conflict between the two theories is string theory. String theory replaces particles with strings that vibrate up to 11 dimensions.
However, string theory comes up against another difficulty: it offers a number of models that describe a universe very similar to ours, and does not really make clear predictions that can be tested experimentally to find out which model is correct. In the 1980s and 1990s, many physicists became dissatisfied with string theory and came up with a series of new mathematical approaches to quantum gravity.
One of the most important is loop quantum gravity, which proposes that the fabric of space and time is made up of a network of extremely small discrete pieces, or loops. One of the strengths of loop quantum gravity is that it seems to completely eliminate time.
Loop quantum gravity is not alone in suppressing time: other approaches also seem to suppress time as a fundamental aspect of reality.
pop up time
So we know we need a new physical theory to explain the universe, and that theory might not include time.
Suppose the theory turns out to be correct. Does it follow that time does not exist? It’s complicated, and it depends on what you mean by existing. Theories of physics do not include tables, chairs, or people, yet we continue to accept that tables, chairs, and people exist.
Because? Because we assume that these things exist on a higher level than that described by physics. It is said that tables, for example, emerge of underlying particle physics buzzing in the universe. But while we have a pretty good idea of how a table might be made up of fundamental particles, we have no idea what time might be. made of something more fundamental. So unless we can find a good explanation for how time appears, it’s not clear that we can just assume time exists. Time may not exist at any level.
To say that time does not exist at any level is like saying that there are no tables at all. Trying to cope in a world without tables can be difficult, but coping in a world without time seems disastrous.
Our whole life is built around time. We plan for the future based on what we know about the past. We hold people morally responsible for their past actions, with the intention of reprimanding them later. we believe officers (entities that can to do things) in part because we can plan to act in ways that will make changes in the future.
But what good is acting to bring about change in the future when, in a very real sense, there is no future to act upon? The discovery that time does not exist would seem to stop the whole world. We would have no reason to get out of bed.
How to get out of trouble
There is a way out of trouble. While physics can eliminate time, it seems to let the causality link: the sense in which one thing can cause another. Perhaps what physics tells us, then, is that causation and not time is the fundamental characteristic of our universe.
If that’s true, then the change can still survive. Because it is possible to reconstruct the meaning of change entirely in terms of causality. At least, that’s what Kristie Miller, Jonathan Tallant and I argue in our new book. We suggest that the discovery that time does not exist may not have a direct impact on our lives, even if it ushers physics into a new era.
Reference article: https://theconversation.com/and-if-time-did-not-exist-183504