What is Time?

in #science7 years ago (edited)

Time is a very complex subject for something we think about everyday

Many people envision time as flowing, like a river. This is helped by the notion that everything happens at the “same time”. In relativity there really is no “same time”, what is considered “now” is not set in stone. On top of no universal “now” existing, it is nearly impossible to tell the past from the future. The only tool is entropy, and that is definitely not set in stone.



Relativity and “Now”

“Now” is essentially everything that happens in a single moment in time. Most people think everywhere has the same “now” at the same time. Since light has a finite speed, you can never actually see the “now” of any object.

This means we need an external way to measure if a weather an event happens at the same time. We can not do this by measuring the passage of time, because any movement has an effect on time. We need to use the only thing that is constant in relativity, light.

For the speed of light to stay constant, space and time must warp. How space and time is warped depends on the observer. Imagine space-time like a loaf of bread, where the ends are both arbitrary points in the past and in the future. Not moving at all will have you going straight down the bread, full speed through time. Anything moving relative to you will be sacrificing some of this speed through time to move through space. In other words, the other object will be moving at an angle. To the object the reverse is true, you would be moving at an angle while it would be going straight through time.

To any object in space-time, now is just a straight cut across the bread. The problem is, they will disagree on what is straight. Image one clock on a train and somebody holding one on the ground next to the track. Due to time dilation, the person sitting off the track would see the clock on the train move just a bit slower than his. He would see it hit twelve just a fraction of a second before his does. The main on the train would see the opposite, his own clock would strike twelve first while the guy on the ground would be moving slower.

When these two people met up later, they would disagree on the order of events, even when the amount of time it takes light to get there is taken into account. This means “now” is not really set in stone, and changes based on the observer.

(Acceleration does actually cause a change in the amount of time elapsed, so that is not relative.)




The Arrow of Time

How does time change? That is a relatively simple question, but with a complicated answer. Some people think of it as a continual flow from one moment to the next, each one exists or is highlighted for the smallest period of time, a moment, and then reality moves onto the next.

This is fundamentally flawed. There is no known mechanism to change all of reality from one moment to the next. In fact, figuring out which moment is the next is hard. Imagine a video of a ball flying through space, now imagine running the video backwards. Both scenarios are entirely possible. For example a ball could be thrown from a planet, decelerate, and fall back down to the ground. As time is reversed, the ground could push up on the ball, launching it into the air and eventually into the hand of the thrower. The physical process is possible, there is just one problem, it isn’t likely.

Entropy is the measure of disorder within a system. The more ways something could be arranged without any significant change, the higher the entropy. This can be shown with a new deck of cards. New decks of cards are often in a specific order (low entropy), when shuffled that order is changed. After a few shufflings, to get the cards fully mixed, shuffling more probably won’t do anything. This means it has higher entropy. Entropy is now a law, but more of a guideline. Things have a tendency to get disordered, but they can become more ordered. With a 52 card deck there are around 8 x 10^ 67 different combinations. One of those is ordered, another that can appear in 2652 different ways is a set where two cards are switched, another with 132600 different combinations has three interchanged, but the vast majority of possibilities is the cards out of any recognizable order at all.

This situation is the same with particles, but they are many orders of magnitude bigger than just the 52 playing cards. This means the particles managing to randomly work together to give the ball enough velocity to launch off the ground is basically zero.

This raises another problem, entropy still hold when looking backward in time. A deck with two or three cards in order is far more likely than a deck with all cards in order. If we knew nothing about how or when the deck was created, we would say it's far more likely that is is a cause of random shuffling of the more disordered states than the leftovers of a more ordered state. This applies to the universe too, taking entropy into account its far more likely the universe came into an ordered state this instant instead of a far more ordered state sometime in the past. Most people just ignore this because that means nothing we do can be trusted and no arguments or learning can take place about any field of physics. Instead, we assume the origin of the universe was for some reason a state with extremely low entropy. The increase of entropy is what gives us an arrow of time.





Humans pass through time, talk about time, and think about time, but we are still a long way from fulling understanding the very fundamentals of time. At least over time we are beginning to understand more.



Want to see more science posts? Subscribe and Upvote!

(Much of my knowledge came from a book I read titled: The Fabric of the Cosmos by: Brian Greene)

Sort:  

Nice post, really well written. Following you now and looking forward to see more of your lectures about science

Great content on a very interesting topic. Time is what you make of it..thanks for sharing @anarchyhasnogods

Now is the point at which the future flows into the past.

Love reading about the mystery of time. Although not a fan of Brian Greene. I don't know what to say but Time does not have a universal definition. We invent the term due to processes around us happening all the time and these things happen somewhat predictably so we can assign a linear parameter to them. Time changes with different events and on smaller scales it can vary but that does not effect the larger scales. All I know is that TIME is all we have.

Yes, time is all we have. But - although everybody owns the same amount of time - there are rich and poor. Because in this particular case not the quantity of time matters but the quality...

Are you saying that poor have more time?
Okay don't answer that. I know what you are saying.

poor people actually tend to have less time, my post on that is coming soon ;)

This I need to see. I am following you and eagerly await this. Kindly look at it in different perspectives: people who choose to not follow wealth, poor vs rich in different cultures. The richer I became the less time I have had. When I was younger and not wealthy, I worked very hard but I still can't recall not having enough time for life.

I meant less time in terms of life-span, as in poverty created by our economic system. That is a good idea for a post a separate post though, I think I will go into more why our economic system makes us choose between wealth and what we truly want to do with our lives and the effects that has. (Choosing not to follow wealth makes you feel like you have more time to do what you want like helping people, but you have less to help people with. ). I think I will take a spin on it like Einsteins paper "Why socialism?"

there is no time , there is no relativity

This science is very useful and become an additional science for me .. hopefully I can also make a post like you .. You make a post about science that full of meaning and useful .. if you have spare time .. visited my blog. I want your criticism and suggestion about my post. Because I also post about science Thank you @anarchyhasnogods for your recommendation and visit ..

I would actually say that 'now' if fixed in a given reference frame. The problem is then that each person will evolve in a different frame, and the way different frames are related to each other mixes time and space (so that we loose the notion of now, in some sense).

not just evolve in a different frame but move between them, so even as a person evolves the now they had before even looses meaning. But I do see your point.

"Moving" between frames does not mean much. You can transform what is happening in a given frame (your rest frame for instance) to another one (my restframe for instance), and assuming we move fast enough, time and space are mixed and we loose the notion. This was actually what I tried to say :p

Time...the space between two events.

Interesting post and nice read @anarchyhasnogods !!
I found your post on my daily science top list and believe your post is undervalued, so I upvoted and resteemed your post !
All the best @minnowhelp

The past never passes, it simply amasses. ;) Great post.

"We need to use the only thing that is constant in relativity, light." you mean the speed of light ? Can you define light ? I am surprise than physicists stick to the speed of something as fuzzy as light for a reference.
http://spaceandmotion.com/

the speed of light is the speed limit of any form of matter. As in the speed of light I could more broadly define it as the speed any object with zero mass travels relative to anything else that is not of zero mass

(light is just the easiest particle to observe that has zero mass)

Congratulations @anarchyhasnogods! You have completed some achievement on Steemit and have been rewarded with new badge(s) :

Award for the number of comments

Click on any badge to view your own Board of Honor on SteemitBoard.
For more information about SteemitBoard, click here

If you no longer want to receive notifications, reply to this comment with the word STOP

By upvoting this notification, you can help all Steemit users. Learn how here!