Why does time seem to move forward? It’s a riddle that’s puzzled physicists for well over a century, and they’ve come up with numerous theories to explain time’s arrow. The latest, though, suggests that while time moves forward in our universe, it may run backwards in another, mirror universe that was created on the “other side” of the Big Bang.
Two leading theories propose to explain the direction of time by way of the relatively uniform conditions of the Big Bang. At the very start, what is now the universe was homogeneously hot, so much so that matter didn’t really exist. It was all just a superheated soup. But as the universe expanded and cooled, stars, galaxies, planets, and other celestial bodies formed, birthing the universe’s irregular structure and raising its entropy.
Richard Feynman discusses why there is a difference between the past and the future, in this clip from his legendary 1964 lecture series at Cornell: The Character of Physical Law.
It’s well worth taking 45 minutes out of your day to hear Dr. F explain why the workings of nature unfold in one direction. You see, while we innately know that the future is different from the past, and so much of our conscious experience is built around the fundamental just-so-ness of time moving forward, the equations of physics describing phenomena from gravity to friction can be run in either direction without breaking the rules. Yet irreversibility is what we observe.
That’s where entropy and probability come into play. When we take into account complex systems, like the jiggles and wiggles of the uncountable atoms that make up our bodies and this chair and my coffee and our world and even out to the scale of the universe itself, there is simply a greater chance that things will become more disordered than less. It’s not that the universe can’t run in reverse, it’s just that there are so many other ways for it not to.
Or as Feynman says, nature is irreversible because of “the general accidents of life”.
This seven-part series, which Open Culture has assembled in its entirety, captures the physicist in his prime, one year before he won the Nobel Prize and became a household name. Feynman was seemingly born for the scientific stage. He had this uncanny ability to weave profound observations of the universe’s inner workings with off-the-cuff (and often brash) humor. James Gleick wrote of Feynman’s unique style and skill:
He had a mystique that came in part from sheer pragmatic brilliance–in any group of scientists he could create a dramatic impression by slashing his way through a difficult problem–and in part, too, from his personal style–rough-hewn, American, seemingly uncultivated.
This clip was a huge influence on my recent video Why Does Time Exist? Although my take scarcely measures up to Dr. Feynman, you can watch below:
The first law of thermodynamics is very famous. It says, “Energy can neither be created nor be destroyed but is converted from one form to another.”
But can you explain the second law of thermodynamics? A bit puzzled, aren’t you?
It’s the very reason I call it the monsters of bioenergetics. Let’s convert these monsters into cute little pixies :)
The second law of thermodynamics says, “The entropy of the universe goes on increasing over time.”
What is entropy?
Entropy is the degree of randomness.
A solid has closely placed molecules. Hence, the randomness in molecules is less. On the on the other hand, in liquids, the distance between the molecules is more. Hence, they have more randomness and more entropy value.
Melting of ice is a good example which illustrates the second law of thermodynamics. When the ice melts, solid gets converted into it’s liquid form. The distance between the molecules increases from solid to liquid and thus, the entropy increases!
Here’s an interesting fact: The human body consumes carbohydrates, breaks it down and stores its energy as ATP, which is a high energy molecule. One would argue that storage of such high energy molecule is against the second law, as entropy of the body is not increasing in this reaction. The entropy increases, but in this case, the entropy of the universe increases because we release carbon dioxide into the surrounding!
Since we are on this topic, let’s address two more terms - Gibbs free energy and enthalpy!
Gibbs free energy
It is the Gibbs free energy which determines whether the reaction will proceed spontaneously to equilibrium without any input from surrounding.
In a reaction, if reactants are unstable (Having more energy) and the products are stable (Having less energy), then the reaction tends to move forward spontaneously without any input from surrounding.
On the other hand, if reactant is more stable than products then for this reaction to happen there has to some input of energy from surrounding.
Hence, if products have less Gibbs free energy than the reactants (i.e. change in Gibbs free energy is negative) then the reaction is spontaneous/exergonic irrespective of whether it is exothermic or endothermic.
If products have more Gibbs free energy than the reactants (i.e. change in Gibbs free energy is positive) then the reaction is non-spontaneous/endergonic.
Enthalpy (H) is a sum of useful energy and non-useful energy. The non-useful part is the Entropy (S) and the useful part is the Gibbs free energy (G).
ΔH = ΔG + TΔS
To summarize all the three terms:
Entropy: Degree of randomness (Non-useful energy)
Gibbs free energy: Energy available to do work (Useful energy)
21 unsettling, uncomfortable, subtly wrong songs for when entropy overtakes you
a sky for shoeing horses under why | a hair on the head of john the baptist saltillo | moon trance lindsey stirling | crimewave crystal castles | rock me now metric | bullets archive | ghosts ladytron | paris is burning st. vincent | the commander thinks aloud the long winters | the 2nd law: unsustainable muse | infra-red placebo | run awolnation | hi psapp | infinitesimal mother mother | lovecraft in brooklyn the mountain goats | empire alpines | when i’m small phantogram | matches to paper dolls dessa | dark doo wop ms mr | hypnosis theme wax tailor feat. marina quaisse
cover art from circle of abstract ritual by jeff frost