Mad About Science: Time

By Brenden Bobby
Reader Columnist

Time is a tricky topic. On the surface, we all know what time is: It’s a measurement of our day. So why do some days seem like they go more quickly than others?

Trying to reduce human perception, individual biases and experiences to a constant metric is nearly impossible. A number of factors may affect your perception of the passage of time: If you’re bored and anxious for a period of time to pass more quickly, you’re more alert and cognizant of your surroundings, which creates the illusion of slow-moving time. 

Conversely, if you’re having fun with friends or hyper-focused on an enjoyable activity, you aren’t focusing on the flow of time, which suddenly seems to go by faster.

Interestingly, it’s been discovered that birds perceive the passage of time differently than humans. For instance, The brain of a starling slows down its perception of time so that it can react more quickly to stimuli, such as the movement of other starlings. This doesn’t mean that the flow of time is changing, but that their brains are processing the information more quickly and efficiently to be suited for specific tasks, like snapping up quick-moving insects while simultaneously avoiding mid-air collisions with other birds.

When you think about time, you probably think about a clock — whether it’s on your phone or the family grandfather clock ticking away down the hall. Time doesn’t make the clock move, per se, but the clock is able to track time fairly accurately through a series of precise mechanical actions. In the Aug. 12, 2021 edition of the Reader, we saw the various types of clocks and how they function. Essentially, clocks receive an input, which is energy, and they output an action at certain, finely-calibrated intervals to denote seconds, minutes and hours almost exactly.

That said, the concept of seconds, minutes and hours are just measurement devices like degrees on a thermometer. They are close approximations for the passage of time, relative to our state of being. You might be wondering what that means. To understand that, we need to zoom out to understand what time really is.

According to Einstein, time exists as a fourth dimension in the universe. Whereas the first three dimensions are length, width and height, time acts as a fourth dimension that keeps things moving and allows energy to travel. This might be a really difficult concept to visualize, and that’s OK. More powerful brains than ours have tried to get to the bottom of this for centuries and we still don’t have a clear answer.

The best way that I’ve found to think about this: Imagine the universe is a piece of fabric that’s growing outward at all times. For the sake of simplicity, let’s pretend this cloth is growing by one foot every hour. This is a very predictable and stable growth while the cloth is taut. Now what happens if you drop a marble on the cloth?

If the marble is heavy enough, you’ll see the fabric distort. Now, part of the cloth might not be growing as quickly as the rest of the surrounding cloth. What happens when you drop a bowling ball onto the fabric? Suddenly a lot of it is being pulled downward, and it’s taking longer for more of the cloth to grow.

This is part of a great experiment you can try at home. While you might not have ever-expanding cloth, you can suspend a sturdy piece of fabric like a comforter a couple of feet off the ground and place heavy objects onto it. After the first object, you can apply directional force by rolling the object into the cloth and watching how it reacts with the other objects and the distortion of the cloth. This is a representation of gravity.

Gravity is a powerful force, and it’s capable of bending not only space, but time. In the case of this experiment, the bowling ball represents a black hole. You’ll notice the black hole bowling ball is pulling down powerfully on the fabric. This gravity well is so powerful that it is even capable of pulling light. Light is the fastest moving energy in the universe that we’re aware of (though there are some exceptions we’ll talk about another day with our professor caps on), and as far as we can tell, the universe is expanding at a speed equal to the speed of light, or 299,792,458 meters per second. That means if the gravitational force of the black hole is strong enough to pull in light, it’s also strong enough to deform time. At some point, an atom being pulled into a black hole reaches a moment where time stops and becomes infinite. You wouldn’t notice this from outside of the black hole, but if you were inside and looking in, it would be as though time had frozen for eternity.

Another very unique interaction of time and speed is something that happens to objects inside of other objects that are moving at incredible speeds. 

Let’s pretend your Tesla is driving at precisely the speed of light. As the driver inside, your experience of time would be different from what it would be outside of the vehicle. At the speed of light, your perception of travel would be near-instantaneous. If you were traveling from here to exactly one light-year away, you would only experience the time during acceleration and deceleration. However, for someone watching you streak across space, they’d have to wait a year for you to arrive at your destination.

Here’s a fun thought experiment: A man, John, living 50 light-years from Earth promised his twin brother, Dave, to visit him on their shared-50th birthday. On that day, John jumps into his light-speed Lexus and takes off. When John arrives, he is still 50, but Dave is 100.

Does your brain hurt yet?

Stay curious, 7B.