Your Brain is a Time Machine: The Neuroscience and Physics of Time

by Dean Buonomano

Unlike the fictional Tralfamadorians of Kurt Vonnegut’s novel Slaughterhouse-Five, we cannot see across time, taking in the past, present, and future at a single glance.

your brain is the best time machine you will ever own. Or put in another way, you are the best time machine that has ever been built.

1.The brain is a machine that remembers the past in order to predict the future.

2.The brain is a machine that tells time.

3.The brain is a machine that creates the sense of time.

4.The brain allows us to mentally travel back and forth in time.

Your brain is composed of a network of close to 100 billion neurons, communicating with each other through hundreds of trillions of synapses.12 Like most computational elements, including the transistors of a computer, neurons receive inputs and generate outputs

For an oversimplified analogy we can look at the World Wide Web, which is also a network of interconnected elements. Think of the webpages as the neurons, and their unidirectional links as the synapses. Which pages are linked to each other is, for the most part, imposed by outside forces: human code writers. But the brain must wire itself; there is no master programmer.

One way or the other, however, the neurons and synapses within our brains manage to connect the dots between events separated by short and long intervals, allowing us to make sense of the events unfolding around us.

Evolution has exploited the fact that because the speed of sound is fairly constant, space and time are complementary—thus telling time allows us to “tell” space.

The best-studied chronopharmacological effect on timing in animals involves manipulating the brain’s dopamine system. Dopamine is an important neurotransmitter, and a modulator of many different brain processes. Most notably, it is damage to a cluster of dopamine-producing neurons located in the brain stem (the substantia nigra) that produces the characteristic tremors and motor deficits of Parkinson’s disease.

Whether of color, sound, or the passage of time, our conscious experiences are in essence illusions, convenient running narratives of what the unconscious brain determines are the most relevant events happening in the extracranial world.

Our ability to compress and dilate time is actually a feature of the brain that we use every day.

Music, in one form or another, is universally present across human cultures. A key ingredient of music is its beat: the periodic pacing that serves as the foundation of a song’s rhythm. Our natural tendency to gravitate towards the beat of the song by tapping, or bobbing our head, is one more example that the human brain is a prediction machine. You do not tap your foot in response to each beat—which is often marked by the strike of a drum—rather, your brain is looking a few hundred milliseconds into the future to predict when the next beat will occur, and synchronizes your movements to match it. Synchronizing our movements with the beat of a song is so easy that sometimes it is easier to tap along than suppress the allure of the rhythm.

To be immortal is commonplace; except for man, all creatures are immortal, for they are ignorant of death. —JORGE LUIS BORGES

So what does the prefrontal cortex do? People who have suffered lesions to the prefrontal cortex can seem entirely normal at first encounter Their motor skills are largely intact; they can understand speech and talk normally; yet depending on the precise location and extent of the lesion, they have distinct deficits in higher-order cognitive functions. These include alterations in short-term memory, personality, attention, decision making, and inhibiting socially inappropriate behaviors. While people with prefrontal lesions can follow instructions and perform many tasks normally, they struggle to execute plans that require multiple steps and flexibly adapt as the circumstances change.

Stephen Hawking states, “The reason we say that humans have free will is because we can’t predict what they will do.”

If the past, present, and future all coexist within the block universe, all choices to be made have “already” been made.

All of the above definitions leave unaddressed one fundamental aspect of free will: the irrepressible feeling that we are in control of our own choices.

What we consciously perceive as free will is presumably preceded by unconscious neural computations that are responsible for making decisions.

Neuroscientists, physicists, philosophers, and legal experts will continue to debate questions pertaining to moral responsibility, determinism, and the role of conscious and unconscious processes in decision making. But perhaps it is time to use our “free will” to embrace the notion that free will is the conscious feeling associated with the neural processes underlying our decisions, decisions that we are fully responsible for because each and everyone of us is the sum of our unconscious and conscious selves.

The brain tells time, generates temporal patterns, remembers the past, and endows us with the ability to mentally project ourselves forwards in time—all in order to predict and prepare for the future.