1. Segment: Recent headlines – Daylight Savings Time and its Impact on our Health

    1. How daylight savings time messes with our circadian rhythm, which seems to lead to higher rates of heart attacks and traffic accidents in the days immediately following a time change. A new study recently presented at the American Heart Association conference shows that there are higher incidents of patients who are admitted with atrial fibrillation, or an irregular heartbeat, after a time change.

      1. https://www.npr.org/sections/health-shots/2018/11/03/663155917/ready-for-the-time-change-here-are-tips-to-stay-healthy-during-dark-days-ahead

      2. https://www.npr.org/documents/2018/nov/afib-admissions.pdf

      3. https://www.acc.org/about-acc/press-releases/2014/03/29/09/16/sandhu-daylight-saving

  2. Segment: Science Fiction/Science fact

    1. Interstellar (2014)

      1. Time travel is a big theme of science-fiction, and for good reason: the idea of inhabiting time as a dimension, and being able to navigate through it, is fascinating despite being difficult to wrap our heads around. At the end of Interstellar (spoilers), Matthew McConaughey’s character, Joseph Cooper, finds himself moving through a kaleidoscopic library that is constantly shifting in odd ways. Joseph, by moving beyond the event horizon of a black hole, now finds himself within a tesseract (think of a 4-D object). This allows him to send a message back in time to his daughter to alter the course of humanity’s future.

      2. When on the tidal planet, an hour for them is equivalent of 6 years back on their spaceship that is orbiting the planet, due to their proximity to a black hole which causes time to be distorted.

    2. Arrival (2016) and the short story it’s based on “Story of Your Life” by Ted Chiang

      1. How do you communicate with a living being that experiences time in a continuous circle? What if we were able to experience time in that way instead of linearly? Imaging that by moving through space you could also move through time! And how that would change your perception of life and events that happen to you.

  3. Segment: Bizarre Science (let’s get weird) – Time flies when you’re having fun

    1. It seems like what we do with our time affects how quickly or slowly we experience it. Why is that?

    2. Our brain encodes multiple types of memory such as factual information like your home address or phone number this is known as semantic memory

    3. It also encodes autobiographical memories, or memories that have a “when” and “where” attached to them. Memories such as, this morning I woke up and laid in bed for ten minutes before I got up and took a shower… they are encoded in sequential order. This is known as episodic memory

    4. We have a fairly good understanding of how the brain encodes spatial information, but how it stores time is a totally different ball game specifically because space and time are so closely related

    5. The discovery of neurons in the hippocampus that encode spatial information–Nobel Prize in Physiology or Medicine given to John O’keefe in 2014 for their discovery

    6. We also know of grid cells, which are located right next door to the hippocampus that help you orient yourself in space–Nobel Prize given in the same year to Edvard Moser and May-Britt Moser for their discovery

    7. While a single place cell might fire every time you’re in a specific location, and only in that location, a single grid cell will fire at multiple locations, spaced a specific distance apart and this firing pattern forms a grid.

    1. Different hippocampal “place” cells that fire at different places in space–https://en.wikipedia.org/wiki/Place_cell

    1. Long Evans rat implanted with electrodes to record activity of a single grid cell while the animal explored the platform–http://science.sciencemag.org/content/312/5774/680

    2. Together, these two types of cells help you to form a cognitive representation of where you are in space.

    3. Even though all the cells in your body can become synchronized to your environment through regular exposure to sunlight/darkness, and other cues–a process we call circadian rhythm entrainment–we don’t have clocks in our brains to tell us what time it is like we have clocks on the wall, in our phones, and on our wrists

      1. Circadian synchronization (open access) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5054915/

    4. What researchers have found is that time isn’t explicitly encoded in the brain. Your “neural clock” doesn’t create an objective representation of time, but a subjective one that is influenced by the type of experience you are having

    5. Scientists have shown just this in findings reported earlier this year demonstrating that in humans, administration of oxytocin, a neuronal signalling molecule associated with social bonding, can compress your sense of time. Making you feel as if time is passing more quickly.

    6. This opens the door for a whole new realm of research to investigate how the subjective perception of our experiences–whether good or bad–affects how we form mental representations of those memories

    7. The scientific community comes to a consensus about what is truly occurring in nature by having multiple groups in multiple different places show that whatever findings they’ve gotten happen repeatedly and it wasn’t just an isolated observation. This has been done in the case of both place cells and grid cells, but we still have a lot to learn about these time cells and the “neural clock”

    8. Time cells article: https://www.medicalnewstoday.com/articles/322953.php

    9. Time cells primary article (pay wall): https://www.nature.com/articles/s41586-018-0459-6

    10. Oxytocin and time perception: https://elifesciences.org/articles/32100

  1. Segment: The Classics

      1. Egyptians use a duodecimal system (base 12) sundial for measuring the time in a day. Sumerians (2000 BC) give Babylonians the base 60 system, which is convenient to make fractions. Eratosthenes divides a circle into 60 parts, and then Hipparchus devises longitude and latitude to have 360 degrees. Ptolemy in Almagest divides 360 further with minutes primea (minute) and minutes secundae (seconds)

      2. https://en.wikipedia.org/wiki/History_of_timekeeping_devices#Timekeeping_devices_of_early_civilizations

      1. A leap second?! https://en.wikipedia.org/wiki/Leap_second

        1. One second = 9,192,631,770 periods of radiation of Cs-133 hyperfine levels of ground state. Earth’s rotation speed changes irregularly, so insertion of leap seconds is also irregular, announced only 6 months in advance. Earth’s moment of inertia changes with geology, for example the 2004 Indian Ocean earthquake shortened a day by 2.7us)

    1. How do we measure time? With a clock! When some Cs-133 atoms are cooled into ball and passed through a microwave, some get excited by the microwave and emit light. You can then tune microwave frequency so that most of the atoms get excited. That’s a second! This clock is so accurate it can measure the effect of relativity by being raised only a inch (gravitational) or walking (kinematic).

    2. But we also know time can pass differently for people in different reference frames. Time and space are unified into space-time through a law called Lorentz invariance, which dictates that the laws of physics should be the same in any reference frame.

    3. Relativity and time dilation:  “When you sit with a pretty girl for two hours you think it’s only a minute, but when you sit on a hot stove for a minute you think it’s two hours. That’s relativity.”

    4. Time can change depending on your reference frame! From special relativity, which is related to physics of things at constant VELOCITY, a moving clock runs slow. So if you’re driving around and the other side of the freeway is stuck in traffic, you can be smug knowing you’re driving faster but aging slower that those stuck in traffic. There is also an effect from gravity itself, and we know this from general relativity, which deals with physics in ACCELERATING frames. The deeper you go into a gravitational field (the more bent space-time is) the slower time will flow relative to someone outside that field (i.e. what happens in Interstellar)

    5. So this brings up the twin paradox, which dictates that’s a twin flying close to the speed of light and returning to Earth will be dramatically younger than their sibling.

    6. It’s ~1970 and Prof. Hafele at Washington University St Louis is preparing for a physics lecture. Wanting to add a little flair to the lecture he does a quick back of the envelope calculation about relativistic effects. He imagines two clocks, one on the ground and another on a plane circling the world. How different would the clocks be? There’s an effect from special relativity which makes the flying clock move slower. Then there’s an effect from general relativity, which speeds up the clock on the plane, relative to the one back at the airport because the one of the plane is outside Earth’s gravity field more than the one of the ground.

    7. Hafele tries to get people sold on the idea of testing it but he has so luck. Finally, after a year, he convinces Keating, an astronomer at the US Naval Observatory, to test this. He gets $8000 to buy two around-the-world tickets for a flight. He will take a SUPER accurate atomic clock on the plane and leave one on the ground, just like he imagined. He goes around the world once going East, so he’s flying in the same direction as the rotation of the Earth and the clock that stays still, and then flies a second time going West, against the rotation of the Earth in the opposite direction of the clock that stays still. Remember, if you’re moving relative to a stationary clock, your clock runs slow so the direction you fly in matters. Going West will make your clock run slower than flying East because the difference in velocity between the two clocks is greater going West than going East. But the plane flies at the same altitude both trips so the gravity effect is the same. What does he find?

    8. Exactly what he predicted! Flying East the flying clock was FASTER by 40 ns, because the gravity effect was stronger than the kinematic effect, but going west the clock was SLOWER by almost 300 ns.

    9. https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment