The Startling Reason Entropy & Time Only Go One Way!

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CHAPTERS:
0:00 Why do things tend towards their lowest energy?
1:27 What is the Second Law of Thermodynamics?
4:35 Why do things tend to go to their lowest energy state?
7:03 How probability enters into the picture
8:41 What is entropy REALLY and why does it only increase
9:58 What increasing entropy implies for the Universe
10:51 How entropy might be related to flow of time
11:48 Learn more about statistics and probability at Brilliant

SUMMARY:
What drives natural phenomena? Why does entropy only increase or stay the same. Why does a pencil on its tip fall to the table?
Things always tend towards their lowest energy state. Why is nature driven this way?

A simple way to think of entropy is disorder. But what’s driving this disorder? What is the underlying cause of higher entropy?

Whenever something happens, some kind of change has to occur. Properties like speed, mass or temperature change. Physics defines the rules that allows us to predict these changes.But if something can change from say configuration A to configuration B, then why shouldn’t the reverse also be allowed from B to A?

When a ball rolls down a hill from a certain height, it should be able to roll back up to the same height. If energy is conserved, then all its potential energy when it is on top of the hill is converted to kinetic energy at the bottom. And this kinetic energy should completely convert back to potential energy, back to the height that the ball originally started from. But this is not what happens. it is irreversible. We can scramble an egg, but we can’t unscramble it.

Conservation laws can’t answer the question why there is a preferred direction to any particular change. Things move in a particular direction as time moves forward. The reason is not as mysterious as it might sound. It all has to do with probability.

If we hold a pencil on its tip and let it go, it will fall and lie horizontally. Why did this happen? When it was held up, it had a high potential energy. When it hit the table, that kinetic energy was transferred to the table and air in the form of heat and sound. Energy is conserved. Buy why did this transfer of energy happen? Why doesn’t the reverse happen? Why doesn’t the energy of the air and heat configure itself in such a way that it results in the pencil standing up. Energy would be conserved in that case too.

What’s really happening is that although energy is conserved, the type of energy has changed. Useful energy has converted to less useful energy. When a system is at a high energy state, it has more energy available to do work. When the pencil was standing on its tip, it had more potential energy. It had more ability to do work. After it hit the table, it had less energy available to do work.

The energy that transferred to the table and air in the form of heat and sound is less useful. The same thing can be applied to a boulder falling from the top of a mountain to the bottom.

The real question is why do some systems tend to transfer their energy to other systems? This is where probability comes in. When the pencil is standing up, there was just a single way you could arrange the potential energy of the atoms that comprise the pencil. Once the pencil has transferred this kinetic energy to the movement of atoms on the table and air in the form of heat and sound, there is an innumerably large number of ways that you could divide up that energy among all the atoms in the surrounding air and table.

So while there are just a few ways that energy can go towards the motion of the pencil, there is a very large number of ways in which that energy could be distributed to the motions and vibrations of atoms in the surroundings. If we assume that the any possible distribution of energy is equally likely, then the case with a mind-bogglingly large number of possibilities is much more likely to occur. In fact, it will occur virtually all the time, and the case with just a few possibilities, basically would never occur.
#entropy
#timeandentropy
Increasing entropy might actually be giving a meaningful definition to the flow of time in our universe. One way to think of time is as things changing. And since things are always changing in the higher entropy direction, we can distinguish higher entropy with the forward movement of time. If there were no change, then perhaps there would be no time.

[krnathan]

This man deserves an award, for explaining complex concepts with so much creativity and simplicity!

[cowgoesmoo]

Jesus christ. I went through high school thinking and being confused about entropy. And I did physics in college, and in thermodynamics the professor said that he did not like the confusion and misconceptions that everyone knows exists about entropy and said he would like to explain it once and for all. I have never been so interested to hear an explanation. He explained it. I immediately became more confused about entropy than ever. This video, by 10:00 has explained the entire concept I ever interacted with into early college physics clearer than I've ever heard. I actually feel motivated to go and understand more about entropy now

[stoneysdead]

This is the first explanation of entropy that explains why the universe started out in such a low entropy state- because it was so much smaller than it is now, and so much simpler because the symmetries had yet to be broken- it just makes sense that there would've been far fewer ways that the system (universe) could be arranged. Why haven't I heard this before? I guess they thought it was just apparent but- I had never even thought about this at all- it's so simple but explains so much. Entropy itself makes more sense when you think about the energy as being "less useful" even though it's conserved. I am definitely going to check out more of your videos- bravo man, well done.

[videosbymathew]

Finally, a great explanation of entropy. I always intuitive had this answer, but no one else ever seems to have described it correctly in videos before, thank you.

[georgerevell]

I love it when you go beyond the generally accepted answer and give your well thought through opinion. Your so brilliant Arvin!

[lookmath]

Your videos have that really phiosophical metaphysical twist in them which makes them special and understandable 👍❤

[Afrobelly]

This was amazing. Until now I'd never been able to make sense of the concept of "increasing entropy in a system" which as a science concept seemed hopelessly vague. Explaining it as a function of end state probabilities made the connection for me. Thank you for that. As a side note, I once dropped a penny onto a table where it bounced a bit until finally coming to rest on edge. I couldn't believe my eyes. In amazement, I left that penny sitting there for maybe 20 minutes. But as you explained--improbable, not impossible.

[Razor-pwxn]

Hi Arvin, could you make a video about the new discovery about the double slit experiment but instead of taking place in space it takes place in time? It would be very interesting to discuss what consequences it implies. "A team led by Imperial College London physicists has performed the experiment using 'slits' in time rather than space. They achieved this by firing light through a material that changes its properties in femtoseconds (quadrillionths of a second), only allowing light to pass through at specific times in quick succession"

[johandam]

Way back when I graduated, my thesis was about exergy (usefull enthalpy for short explanation). This video captured that concept. This is quite an achievement

[Laser]

Now I know why things keep changing in the universe. The culprit is Entropy. Everything changes because of transfer of energy to one thing to another. Thanks Mr. Arvin Nash.

[hisss]

I may now, for the first time in my life, finally, have a slight bit of a beginning of an understanding of what entropy means. "Disorder" was always so vague, I never got who or what decided what was ordered and what was disordered. I don't quite speak maths, so things like statistics and probability are over my head, but at least the concept is starting to make sense. My teachers could never achieve that, so thank you. There might still be hope for me.

[matkosmat]

Time as a statistical phenomenon! Thank you, Arvin, your explanations are always spot-on.

[bmaverickoz]

I like that you referenced Lee Smolin, who is so invested in probing the status of time of fundamental (well, causation anyway, which is manifestation of time). I think his work is really valuable in this space, and your popularising of the subject is truly inspired Arvin :)

[Matlacha_Painter]

Arvin’s qualitative explanations of these mathematically complex phenomena are especially valuable to me having been frustrated by the Principia, as well as his perfect articulation makes me say “eureka”.

[timjohnson]

"Time being a statistical phenomenon" is an interesting thought, but is that reality? If it is, then what does that mean in the context of spacetime?
Love your videos, Arvin. They are clear and thought provoking.

[macsarcule]

This so clearly answered questions I’ve been puzzling over for years. I have new questions to puzzle over now, and that’s extra awesome! Thank you, Arvin! ✌️🙂

[jeffreymartin]

There is nothing more satisfying than when that light bulb goes on. Often seemingly on it's own when least expected. You realize: Of course ! Thank you once again Arvin!

[NoActuallyGo-KCUF-Yourself]

Great timing on this one! I watched it right before one of my chemistry students asked about thermodynamics. I definitely passed this on as a study aide.

[gafyndavies]

No matter how bad a day I'm having, when I hear "That's coming up, right now!" a huge smile erupts on my face 😊

[starrynightlyrics]

I will remember your name ten years from now. You explained that concept about life better than my teachers ever did. THAAANKS A LOT !!!