Why Does Time Go Forward?

Why does time go forward? How does Entropy relate to the direction of time? What really is time, and what gives it a direction? The Arrow of Time.

Hi! I'm Jade. I draw pictures that move and become animated physics videos.

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We all think of time as having a direction. Yesterday is the past, tomorrow is the future. But what if I told you that none of the equations that govern our universe have anything to do with the direction of time. So what gives time its direction?

The arrow of time is given purely by the second law of thermodynamics. The second law of thermodynamics says that the ENTROPY of the universe is always increasing. Entropy is the measure of randomness and disorder of a system. One day our universe will reach a point of maximum entropy, and time as we know it will cease to exist. There will be no distinction between past, present and future. This one aspect of our universe (entropy) is what gives time its arrow. In the past there was lower entropy than now, and in the future there will be higher entropy.

So why is Entropy always increasing? Well, disorder is more likely than order. There are plenty of ways to be in a disordered state, while there are very few ways to be in an ordered state. Disorder is more probable than order.

The real question is, why was entropy ever low in the first place? It seems kind of strange that such an unlikely event should happen. This question is one of the biggest unsolved mysteries in physics. One theory is that we live in a multiverse, where baby universes are being born all the time. The baby universe start with low entropy, but the entropy of the entire multiverse increases.

If physicists manage to crack that one, all questions will be answered, we'd be able to understand the mysteries of our universe and the Arrow of Time.

[upandatom]

Hi Everyone :) Please comment, like and share this video to help my channel grow so I can make more videos for you guys! I will be forever grateful :) Yours truly, Jade (miss physics) xxx

[aidanandrewson]

This is by far the best explanation of entropy I've heard, Thank you for clearing all that up!

[DaveTexas]

“Time flies like an arrow, but fruit flies like a banana."

[TraneFrancks]

One of the things that has always interested me is that while entropy of the universe is increasing, baryonic matter seemingly never stops increasing its organizational complexity. We went from opaque plasma to galaxies and life. I don't imagine that the processes that have lead to this organizational complexity have stopped, so ... the contrast is striking.

[nigeldepledge]

"Disorder" is often used as a synonym for entropy, but the two are not the same thing. Entropy is a measure of the degrees of freedom a system has, or the number of different ways it can change over time.

For instance, in your six-dice example, you make it sound like 6, 6, 6, 6, 6, 6 is less likely than, say, 2, 3, 1, 5, 5, 1, but the two outcomes have exactly the same likelihood. The former looks ordered to us apes, whereas the latter does not. A better illustration is rolling your six dice in a tray and having all six form a neat rectangle in one corner : that *would* be a low-entropy configuration because the dice would spontaneously have to constrain the ways they can move. And you'd need to roll them an awful lot more than 46, 000-odd times to have any reasonable chance of seeing this happen.

[uncledarren]

The problem with with entropy as an acceptance of time moving forward is that it is STILL based on OUR constant perspective. Our perspective of time is a single point of a foot print of a higher dimension (time) which we can not see any other way except one dimensionally. As the present.

[VishalParmar-wcrb]

Wow! please do more videos about TIME. I used to hate Physics (since it had lots of equations and math) and hence took Electronics & Telecommunications as my primary subject...this channel made me realise physics can be interesting.And yes, you explained it really well. Thankyou

[joshuacornelius]

If you could reverse time, the inverse of the 2nd law of thermodynamics works just fine. The reason why time goes "forward" is because our consciousness is a product of a physical substrate (our brains) relies on a electrochemical system that only works in one temporal dimension. You couldn't still have consciousness if you reversed causality, the flow of electrons, or the dynamics of synaptic connections within the nervous systems. Memory, sensory input, information processing all would not exist and do there would be no consciousness to observe the 'flow of time'. The wave function doesn't care about time and gets along quite nicely with or without it.

[Dragonblaster]

The example I always give is: "You have a jar which contains a neat layer of soot and a neat layer of flour. How long would you need to randomly shake the jar to get a grey mixture of soot and flour?"

Most people correctly guess "not very long".

"So how long do you think you'd need to shake it to turn it back into a neat layer of soot and a neat layer of flour?"

After a little thought, most people say, "A long time... a very long time."

[SpiritG]

Finally, someone addresses the question of how the universe could have begun in a low entropy state. I've wondered this, but Google searches turn up nothing on this specific issue. So thanks for that.

[billcosbyeatsbabies]

It's hard to believe this girl only has <1k subscribers, she is awesome and deserves much more! :)

[jonminer]

This year, August 25, 2020, it is known that the redshirt upon which the expansion of the universe is based, is not caused by the recessional velocity. So those far distant galaxies are not moving away from us, and the big bang as a single point must be incorrect as well since the time needed for the size of the present universe can't be true based on the age of distant galaxies based on their sizes and numbers of young stars.

[Ole_Rasmussen]

You're really good at explaining things. I am new subscriber man.

[Hammillian]

I know little about this (time arrow), but am very interested. What occurs to me is that there is other much clearer indicator of the time flow, which is information storage: information can only be had from past events or situations. Life beings (same as automatic devices) take decisions (and actions) for the future based on information received from the past.

Does it relate in any way to entropy increase?

Thanks and congrats for your videos: I love them more than other divulgating authors' for yours are short enough to be watched in short stolen periods of my busy life.

[FunkyStudent]

As you said, entropy exists due to probability. If that's the case given enough time wouldn't the universe eventually return to a low entropy state?.

[stewiesaidthat]

Time is a measurement of motion. Going from an ordered state to an unordered state and back to an ordered state is not a reversal of time. It is a cycle. Each completed cycle is counted as 1. Programming a clock to cycle backwards does not reverse time. The same applies for the spin of an electron. You don't uncount cycles.

[carboxysome]

So when we decrease chaos in our room, we are actually adding to overall chaos even more than it was before we cleaned the room? Well that's depressing.

[Dyslexic-Artist-Theory-on-Time]

Low entropy could be formed by an ongoing process of symmetry forming and breaking. I have read that the electron is the most spherical object in the Universe, each photon electron coupling or dipole moment could be a branching point for increasing entropy.

[germanjimenez]

I think it's a perception problem. We perceive time moving forward because our biology, chemistry, memories depend on things moving in the same direction. If our memories, experiences were not dependant on these laws, we'd be able to see the universe and all of the time at will.

[amphibiousone]

Oh, this one os so good! You are awesome Jade! Just yesterday, I was trying to help my friend understand this, concept. You have just made this so easy for me. Time to share it with her. You are a much better teacher than me. Thank You SooooMuch😄👍👊🌈