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# Time doesn't actually exist - discuss watch

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1. (Original post by Fernand126)
But isn't it actually possible to decrease entropy, although it's not entirely natural and very unlikely?

I'm just a high schooler, though, so don't mind me if I'm being too dumb.
Not quite. It's possible for a reaction to have negative entropy, but that would have to be balanced out by a larger increase in the entropy of the surroundings (for example, heat given out). It's impossible for a reaction to take place which leads to a decrease in the entropy as the universe as a whole.

(Original post by Captain Jack)
I don't understand what entropy of the universe is as I haven't ever read anything on that topic - is there a plain English explanation anywhere?
In simplified terms, entropy is a measure of randomness or disorder. According to physical laws, whenever a reaction takes place the entropy of the universe must increase. Reversing those reactions would result in a decrease in the entropy of the universe, which is thermodynamically impossible.
2. (Original post by james1211)
Yes, i would say so, as you can categorise "events" that have happened before now, and after now. If you can distinguish that, you can create a system to measure between those events.

Something doesn't have to be physical to exist. Does maths exist? Does thought exist? Of course they do, they just aren't physical. Yes we've made them up, but they still exist.
What if memory is just residue / by-product of a reaction? There is still only now, even if you think you can 'remember' something that has happened.

I'm not explaining it very well, I need Brian Cox to come on and say what he said again
3. (Original post by Captain Jack)
What if memory is just residue / by-product of a reaction? There is still only now, even if you think you can 'remember' something that has happened.

I'm not explaining it very well, I need Brian Cox to come on and say what he said again
Brian Cox may as well be high when he comes out with most of his programs. He's very good at engaging his audience
4. (Original post by Blazar)
Not quite. It's possible for a reaction to have negative entropy, but that would have to be balanced out by a larger increase in the entropy of the surroundings (for example, heat given out). It's impossible for a reaction to take place which leads to a decrease in the entropy as the universe as a whole.
Very clarifying, thanks.
5. Can someone explain what entropy is? I ve come across this word multiple times
in various topics and even though i ve searched to some extend for its meaning i dont seem to really get it. As far as i understand it is the tendency of an isolated system to become disorder in the microscopic level. A higher entropy is a situation were things are more disordered and since in an isolated system the entropy always increases, the higher entropy is infact later in time. Question : when we say "entropy is increasing" do we mean that the systems' disorder is increasing? Is there a limit on how disordered something is?
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6. The rising/setting of the sun.
7. In terms of physics, time is a relationship between distance and speed.

So time always exists. Because everything has been moving.

In terms of philosophy, it all depends on who or what you really are. Do you think who or what you are?
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8. (Original post by Captain Jack)
I've been doing a horticulture course, learning about energy in plants and growth. Then saw a Brian Cox programme where he said time could in fact not exist at all. In fact, everything we experience could just be energy and reactions. Which meant if you were able to reverse all those reactions you could effectively travel back in "time".

Has anyone else heard this hypothesis? Is it an actual theory?
I'm inclined to think it doesn't and it's most certainly something that's been considered. Einstein himself posited that past and future are just illusions and that everything is in reality occurring in the NOW, it's just our perception causing us to experience time as a linear flow.
Can someone explain what entropy is? I ve come across this word multiple times
in various topics and even though i ve searched to some extend for its meaning i dont seem to really get it. As far as i understand it is the tendency of an isolated system to become disorder in the microscopic level. A higher entropy is a situation were things are more disordered and since in an isolated system the entropy always increases, the higher entropy is infact later in time. Question : when we say "entropy is increasing" do we mean that the systems' disorder is increasing? Is there a limit on how disordered something is?
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In layman terms, entropy is the measure of randomness and "how evenly spread out" a system is. That's why when you open a hot oven door for example, the heat flows outwards, so that the temperature of the whole kitchen becomes even and "spread out" instead of localised inside the oven. Without entropy the oven would remain eternally hot, or at least for a very, very long time.

And yes, increasing entropy refers to the disorder/randomness of a system increasing. There's obviously limits to entropy in specific reactions, but if you're referring to the universe as a whole then no one knows. The universe could carry on expanding forever, or reach a maximum state of entropy and then collapse in on itself.
10. Our current understanding of physics is that for an event to occur, time needs to be present. Without time, something cannot happen.

Time is an object interwoven with space and as such, we know time exists because the universe does. Our laws and theories work excellently with time and in fact if you removed time, everything would fall apart.

There is absolutely no evidence to suggest that time is abstract.
11. It does exist -- It's 18:39!
12. (Original post by Plantagenet Crown)
I'm inclined to think it doesn't and it's most certainly something that's been considered. Einstein himself posited that past and future are just illusions and that everything is in reality occurring in the NOW, it's just our perception causing us to experience time as a linear flow.
But out concept of counting time is just that - a measure of our perception of how things have happened and applying a measure to how long ago we perceived them to happen. That makes it a real concept.
13. (Original post by james1211)
But out concept of counting time is just that - a measure of our perception of how things have happened and applying a measure to how long ago we perceived them to happen. That makes it a real concept.
I guess it depends on how you're defining "real". If you mean it seems real to us and in our experience it's real, then yes. But what I meant was whether linear time exists in an ultimate reality.
14. I keep hearing this man chat moronic nonsense.
15. (Original post by Plantagenet Crown)
In layman terms, entropy is the measure of randomness and "how evenly spread out" a system is. That's why when you open a hot oven door for example, the heat flows outwards, so that the temperature of the whole kitchen becomes even and "spread out" instead of localised inside the oven. Without entropy the oven would remain eternally hot, or at least for a very, very long time.

And yes, increasing entropy refers to the disorder/randomness of a system increasing. There's obviously limits to entropy in specific reactions, but if you're referring to the universe as a whole then no one knows. The universe could carry on expanding forever, or reach a maximum state of entropy and then collapse in on itself.
Thank you, that is a great explanation
17. (Original post by Plantagenet Crown)
I'm inclined to think it doesn't and it's most certainly something that's been considered. Einstein himself posited that past and future are just illusions and that everything is in reality occurring in the NOW, it's just our perception causing us to experience time as a linear flow.
Yes, it's certainly interesting a concept and it does make sense to me.
18. (Original post by Blazar)
I mean just that. The entropy of the universe. The physical quantity of entropy in joules per kilogram per mole.
It's per kelvin mate
19. Oops, typo. My bad, it is kelvin.
20. I don't understand arguments that suggest time isn't real.

Also, I'm a naiive realist but have no way to prove this.

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