Associate Professor Sam Baron from the Australian Catholic University on how developments in physics are changing our understanding of the universe
is there time The answer to this question may seem obvious: of course it does! Just look at a calendar or a clock.
But developments in physics suggest that the non-existence of time is an open possibility that we should take seriously.
How can that be and what would that mean? It will take a while to explain, but don’t worry: even if time doesn’t exist, our life will go on as usual.
A crisis in physics
Physics is in crisis. In the last 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 tiny world of particles and particle interactions. general relativity describes the big picture of gravity and how objects move.
Both theories work very well on their own, but the two are believed to be in conflict with each other. Although the exact nature of the conflict is disputed, scholars generally agree that both theories need to be replaced with a new, more general theory.
Physicists want to set up a theory of “quantum gravity”. replaced general relativity and quantum mechanics while noting the extraordinary success of both. Such a theory would explain how the big picture of gravity works at the miniature level of particles.
Time in Quantum Gravity
It turns out that it is extraordinarily difficult to construct a theory of quantum gravity.
An attempt to overcome the conflict between the two theories is string theory. String theory replaces particles with strings vibrating in up to 11 dimensions.
However, string theory faces another difficulty. String theories provide a set of models that describe a universe broadly like our own, and they don’t make really clear predictions that can be tested through experimentation to see which model is correct.
In the 1980s and 1990s, many physicists became dissatisfied with string theory and developed a number of new mathematical approaches to quantum gravity.
One of the most prominent of these is Quantum Gravity Loopwhich proposes that the fabric of space and time consists of a network of extremely small discrete pieces or “loops”.
One of the notable aspects of loop quantum gravity is that it appears to eliminate time entirely.
Loop quantum gravity isn’t the only one to do away with time: a number of other approaches also appear to be removing time as a fundamental aspect of reality.
So we know that we need a new physical theory to explain the universe, and that theory may not involve time.
Suppose such a theory turns out to be correct. Would it follow this time is not present?
It’s complicated and it depends on what we mean by it exist.
Theories of physics do not involve tables, chairs, or people, and yet we still accept that tables, chairs, and people exist.
Why? Because we assume that such things exist at a higher level than the level described by physics.
For example, we say that tables “grow” from an underlying physics of particles zipping around the universe.
But while we have a pretty good sense of how a table might be made up of fundamental particles, we have no idea how time might be “made” out of something more fundamental.
Unless we can find a good description of how time arisesit is not clear that we can simply assume that time exists.
Time may not exist on any plane.
time and agency
To say that time does not exist on any plane is like saying that there are no tables at all.
Trying to navigate a world without tables may be difficult, but trying to navigate a world without time seems downright disastrous.
Our entire life is built around time. We plan for the future in light of what we know about the past. We hold people morally accountable for their past actions with the aim of blaming them later.
We believe we are agents (Entities that can doing things) in part because we can plan to act in ways that will bring about change in the future.
But what’s the point of acting to bring about change in the future when there is literally no future to act for?
What is the use of punishing someone for a past action if there is no past and therefore apparently no such action?
The discovery that there is no time seems to bring the whole world to a standstill. We had no reason to get up.
There is a way out of the mess.
While physics could eliminate time, it seems to go causation intact: the sense in which one thing can evoke another.
So maybe physics is telling us that causality, not time, is the fundamental feature of our universe.
If true, the agency can still survive. Because it is possible to completely causally reconstruct a feeling for action.
At least that’s what Kristie Miller, Jonathan Tallant and I argue our new book.
We assume that the discovery that time does not exist may not have a direct impact on our lives, even if it propels physics into a new era.
https://www.theweek.co.uk/news/science-health/956460/does-time-exist is there time | The week Great Britain