Time is one of the most familiar and bewildering phenomena in the universe. It is fundamental to human experience and a feature of reality everyone feels like they understand until they start thinking about it. Yet advances in modern physics suggest time is not a fundamental feature of the world, but assembled by a more primal feature of existence.
Time is a nebulous term that slips through our fingers as quickly as pebbles in time’s hour glass. Of course, time exists in the trivial sense that humans use it all the time. There is a theory of time embedded in the the way we use language, which makes it impossible to formulate a sentence without invoking some particular tense. When physicists suggest time is an illusion, what they really mean is time is not fundamental to reality.
Einstein’s General Theory of Relativity revealed any theory of gravity was also a theory about the nature of space and time. In particular, Einstein revealed that space and time were intertwined together in a four-dimensional manifold. Gravity was a product of matter bending the curvature of space-time.
General relativity vs quantum mechanics
The General Theory of Relativity is the best working theory of gravity, but physicists know it is far from complete. Specifically, general relativity is incompatible with its sister theory, quantum mechanics, the physics of the very small. Physicists face the daunting challenge of finding a theory that blends general relativity with quantum mechanics, as the former breaks down at very short distances.
Einstein single handedly formulated general relativity. Nevertheless, developing a theory of gravity that incorporates quantum mechanics, otherwise known as quantum gravity, has bamboozled heavy weight intellectuals for decades. This is in part due to the fact that physicists have always formulated theories within time and not without.
The problem is a theory of gravity gives rise to paradoxes about the nature of time. For example, the theory of gravity presupposed that the passage of time changes. But if that is true, then the standard by which the river of time changes also changes. As a result, the variable of time is dropped from physical equations, pushing any theory of gravity to the brink of incoherence.
Down the rabbit hole
There have been various attempts to blend quantum mechanics with general relativity, from loop quantum gravity to string theory. What these approaches share in common is that they state time is not a fundamental feature of reality but emerges from a deeper level within the abyss of being. They suggest space-time is made up of tiny, indivisible units that can be put together in various ways.
These atoms are not like hydrogen atoms, which interact in the medium of space, but comprise space itself. Since these particles makeup space, they cannot be said to be tiny, as they do not occupy a particular location in space. Although these ideas are difficult for the human mind to grasp, they do help solve certain problems in physics.
According to general relativity, for instance, space-time breaks down at the horizon of a black hole. Consequently, any material that falls into the black hole is forever lost, since there is no place or time for the material to fall into. Emergent theories of time suggest that space undergoes a phase transition at the horizon of a black hole. Since a black hole does not have an internal volume, the units that makeup space-time are converted at its horizon into absolute nothingness. Any material that falls into the black hole is preserved but in a form that surpasses space, time and human understanding.
On the emergence view, there is no “beginning” to time. Instead, the big bang was a phase transition from a spaceless state to a spacial state, in a similar way a water molecule can crystallize from a liquid state into a solid state. (To ensure the water you ingest is clean, visit FoodForensics.com.)
These theories are wildly speculative and it’s possible that our minds didn’t evolve the right cognitive tools to solve the challenge at hand. What is safe to say is that whatever the fundamental nature of reality might be, it will ultimately abandon our intuitions about the universe somewhere between the horizon of a black hole and its singularity.