What is time? Obviously, the simple answer is the 24-hour daily cycle that’s broken down into minutes and seconds, to which we've all chained ourselves. But even in those minutes and seconds, the human perception of time is different for each specific person. When it comes to theories about time, that’s really the only thing that everyone can agree on. From there, scientists and researchers argue about whether or not time is experienced similarly by the earth’s population, or if time speeds up and slows down for people moving faster or slower. How we perceive time can not only alter our memories, but it can change the way we go about our days.
Is time linear? This is a question that’s plagued scientists and philosophers for centuries, and it’s likely to continue confounding them until time folds in on itself and puts the world's philosophers out of a job. (Unless that’s already happening right now.) There’s something noble about the study of time. No one will ever truly understand the "real" nature of the passage of time; all researchers can hope to do is try to figure out how we understand the way time passes around us.
There are some intriguing concepts on this list, and at least one of them, if not all, will make your head explode.
Time May Be More Like a Disk Than an Arrow
Physicist Sean Carroll is trying to understand how time works - specifically, Einstein's theory that everything is happening all the time. If that's true, why do we remember the past and not the future? Why is cracking an egg an irreversible process?
Carroll explains that "the arrow of time" is traditionally linked to the idea of entropy:
Entropy is just a measure of how disorderly things are. And it tends to grow. That’s the second law of thermodynamics: Entropy goes up with time, things become more disorderly. So, if you neatly stack papers on your desk, and you walk away, you’re not surprised they turn into a mess. You’d be very surprised if a mess turned into neatly stacked papers. That’s entropy and the arrow of time.
That led him to the question, why was the entropy of the universe lower in the beginning than it apparently is now? Carroll believes that the answer lies in understanding what gave the Big Bang its original properties, and how that connects to whether or not time is really a straight arrow or more like a way of describing coordinates within a single universe: "So that static universe in the middle has time as a coordinate but there’s no arrow of time. There’s no future versus past, everything is equal to each other."
Time Depends on Your Subjective Experience
A person's time perception is essentially their subjective experience of the passage of time, or the perceived duration of events, which differ significantly between different individuals and in different circumstances. While physical time is more or less objective, psychological time is subjective and potentially malleable. Psychologists believe that our neurological systems govern the way we observe time, and that the observance of the duration of events is one of the few things that's not connected to specific sensory pathways, but rather uses a highly distributed system in the brain - which is why it is affected differently by smell, taste, and sound.
Doing More Stuff Gives You More Time
Neuroscientist David Eagleman believes that by focusing on a specific task, you can slow down time, or at least slow down the way your brain perceives the passage of time. Although "brain time," as Eagleman calls it, is subjective. He suggests that the more detailed the memory, the longer the moment seems to last.
“This explains why we think that time speeds up when we grow older,” Eagleman says, "why childhood summers seem to go on forever, while old age slips by while we’re dozing. The more familiar the world becomes, the less information your brain writes down, and the more quickly time seems to pass."
So if you want to have a longer, potentially better day, start doing some stuff. Your significant other could probably use a new book shelf.
Music Changes Your Perception of Time
While we perceive of time as a vast continuum, people can't help but chop it up into units as a way to describe that time. Composer Jonathan Berger believes that music creates discrete temporal units that don't align with "the discrete temporal units in which we measure time." Instead, music puts our consciousness in a separate, "quasi-independent concept of time" that's able to distort or negate what he calls “clock-time.” He refers to this theory as "musical hijacking" and is working on pieces that he hopes can further distort time for the listener.