In general relativity, ALL of time and space are a single four dimensional geometry. In this theory, there are simply points in space time. Each point also has a past 'light cone' and a future 'light cone'. Anything in the past light cone will be 'in the past' for all observers at that point. Things in the future light cone will be 'in the future' for all observers at that point. But things not in either will be 'in the past' for some observers and 'in the future' for others.
In this description, both the 'past' and the 'future' are real and exist. Causality goes from the past light cone into the point and from the point into the future light cone. We have memories of the past and not of the future simply because of this aspect of causality.
Things get a bit strange when quantum mechanics enters the picture. We don't have a good theory of quantum gravity, so we cannot say exactly what happens to the geometry of spacetime when subject to QM. It likely becomes probabilistic, as all things quantum tend to be.
In any case, in QM, the future, at least, is indeterminate. That doesn't mean it isn't real. SOME events are determined (like the eclipse in 2024), while others are not (like the time when a uranium atom decays).
But it also isn't clear to me whether the *past* is determined in QM. If the information from the past mixes with the environment to a sufficient extent, it seems that the past becomes just as probabilistic as the future. When the information is impossible to retrieve, the past would be undetermined.
As an example (there are many), the statement that 'a T-Rex stood in this location precisely 67 million years ago' may simply not have a fixed truth value. If there is no way to retrieve that information from the past using what exists in the present, then there simply is no truth of the matter.
In this description, both the 'past' and the 'future' are real and exist. Causality goes from the past light cone into the point and from the point into the future light cone. We have memories of the past and not of the future simply because of this aspect of causality.
Things get a bit strange when quantum mechanics enters the picture. We don't have a good theory of quantum gravity, so we cannot say exactly what happens to the geometry of spacetime when subject to QM. It likely becomes probabilistic, as all things quantum tend to be.
In any case, in QM, the future, at least, is indeterminate. That doesn't mean it isn't real. SOME events are determined (like the eclipse in 2024), while others are not (like the time when a uranium atom decays).
But it also isn't clear to me whether the *past* is determined in QM. If the information from the past mixes with the environment to a sufficient extent, it seems that the past becomes just as probabilistic as the future. When the information is impossible to retrieve, the past would be undetermined.
As an example (there are many), the statement that 'a T-Rex stood in this location precisely 67 million years ago' may simply not have a fixed truth value. If there is no way to retrieve that information from the past using what exists in the present, then there simply is no truth of the matter.
