Time may not exist at all, according to physics

Does time exist? The answer to this question may seem obvious: Of course yes! Just look at a calendar or a clock.

But developments in physics suggest that the non-existence of time is an open possibility, and one that we should take seriously.

How is that possible, and what would that mean? It will take a little time to explain, but don’t worry: even if time doesn’t 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 extremely successful physical theories: general relativity and quantum mechanics.

Quantum mechanics describes how things work in the incredibly small world of particles and particle interactions. General relativity describes the overview of gravity and how objects move.

Both theories work extremely well on their own, but the two are thought to conflict with each other. Although the exact nature of the conflict is disputed, scientists generally agree that the two theories should be replaced by a new, more general theory.

Physicists want to produce a theory of “quantum gravity” that replaces general relativity and quantum mechanics, while capturing 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 producing 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 vibrating in 11 dimensions.

However, string theory comes up against another difficulty. String theories provide a range of models that describe a Universe broadly like ours, and they don’t really make clear predictions that can be tested by experiments to determine which model is correct.

In the 1980s and 1990s, many physicists became dissatisfied with string theory and came up with a range of new mathematical approaches to quantum gravity.

One of the most important of these 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 remarkable things about loop quantum gravity is that it seems to completely eliminate time.

Looping quantum gravity is not the only way to abolish time: a number of other approaches also seem to abolish time as a fundamental aspect of reality.

Emergence time

So we know that we need a new physical theory to explain the Universe, and that theory might not involve time.

Suppose such a theory turns out to be correct. Would it follow this time does not exist?

It’s complicated, and it depends on what you mean by to exist.

The theories of physics don’t include any tables, chairs, or people, and yet we still accept that tables, chairs, and people exist.

Why? Because we assume that such things exist on a higher level than the level described by physics.

We say that the tables, for example, “emerge” from an underlying particle physics hissing around the Universe.

But while we have a pretty good idea of ​​how a table could be made up of fundamental particles, we have no idea how time could be “made up of” anything more fundamental.

So unless we can come up with a good explanation for how time emerges, it’s not clear that we can just assume time exists.

Time may not exist at any level.

Time and agency

To say that time does not exist at any level is like saying that there are no tables at all.

Trying to manage in a world without tables can be difficult, but managing in a world without time seems positively disastrous.

Our entire lives are built around time. We plan for the future, in light of what we know from the past. We hold people morally responsible for their past actions, with a view to reprimanding them later.

We believe ourselves to be officers (entities that can to do things) in part because we can plan to act in a way that will lead to change in the future.

But what is the point of acting to bring about change in the future when, in a very real sense, there is no future to act for?

What is the point of punishing someone for a past action, when there is no past and therefore, apparently, no such action?

The discovery that time does not exist would seem to immobilize the whole world. We would have no reason to get out of bed.

As per usual

There is a way out of trouble.

While physics might eliminate time, it seems to let cause intact: the sense in which one thing can lead to another.

Perhaps what physics is telling us, then, is that causation and not time is the fundamental characteristic of our Universe.

If that’s true, then the agency can still survive. For it is possible to reconstruct a sense of agency 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 have no direct impact on our lives, even if it propels physics into a new era.

Sam Baron, Associate Professor, Australian Catholic University.

This article is republished from The Conversation under a Creative Commons license. Read the original article.