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[Eagleon]

Yeah, physics looks different going forwards than backwards in time. Occam's razor is ludicrously important in science.

What do we know of what's more likely here, though? It's the way the entire universe works - I don't see why it should care about our ideas of whether glass should shatter forwards or backwards or both at once or neither.

[Descan]

Because a shattered glass has higher entropy than a whole glass.

[Lagslayer]

Because a shattered glass has higher entropy than a whole glass.

That statement is complete nonsense. Why would you define an unbroken glass as the baseline for measuring entropy?

[Putnam]

Why would you assume that observation, even observation that doesn't directly involve humans, is fundamentally flawed instead of just looking at reality?

Also, no baseline was defined there. It's a 100% relative piece of information. Broken glass has more entropy than unbroken glass. This is fact. It's like saying that the Sun has more mass than the Earth.

[i2amroy]

It doesn't matter if you define the shattered or the whole glass as the baseline, the shattered glass will always have more entropy. Moving the zero point on a number line has no effect on which of two numbers is bigger; X<Y will still be X<Y regardless of if 0 is the zero point or if 1,000,000 is your zero point (it's just that in one case you are comparing X and Y, and in the other both are shifted by -1,000,000).

[Lagslayer]

So since it isn't all put together in an arbitrarily defined manner, it has more entropy? What if the glass is intended to be in small shards? Would that mean the properly formed glass has more entropy? It's not a simple matter of a baseline, it's also assuming a particular vector has more meaning. This means nothing on such a large scale.

No, it is not like saying the sun has more mass than the earth. That operates on the molecular level and smaller. It's comparing apples to pigeons. "Entropy" has no meaning unless it's a much smaller scale.

[Eagleon]

Why would you assume that observation, even observation that doesn't directly involve humans, is fundamentally flawed instead of just looking at reality?

Also, no baseline was defined there. It's a 100% relative piece of information. Broken glass has more entropy than unbroken glass. This is fact. It's like saying that the Sun has more mass than the Earth.

Yes, I know. But it's completely inconceivable that entropy functions in reverse, and that we're just forgetting the past? I don't know, it's probably pointless, almost certainly non-falsifiable, because we're going to experience it this way anyway, but it's interesting to me anyway. It's information gradually being removed from a system instead of created. Why shouldn't it work this way? What keeps it from working this way other than our expectations that the way we experience time is based on memories forming rather than being destroyed?

The fact that it's such a big thing for physicists to prove (or even just the fact that it warrants a great big wiki page attempting to prove it) is weird to me, because I can't see any way to do so without the assumption that observation isn't flawed. From my understanding of science, the stance for things like this is "don't even bother, it's philosophy"

[Putnam]

So since it isn't all put together in an arbitrarily defined manner, it has more entropy? What if the glass is intended to be in small shards? Would that mean the properly formed glass has more entropy? It's not a simple matter of a baseline, it's also assuming a particular vector has more meaning. This means nothing on such a large scale.

No, it is not like saying the sun has more mass than the earth. That operates on the molecular level and smaller. It's comparing apples to pigeons. "Entropy" has no meaning unless it's a much smaller scale.

...Except that that's completely false. Entropy is "a measure of the number of specific ways in which a thermodynamic system may be arranged", which means that it applies to all closed systems, macroscopic or no. The statement "irreversible processes increase the combined entropy of the system and its environment" also means that breaking glass (which is an irreversible process) will always increase entropy.

Why would you assume that observation, even observation that doesn't directly involve humans, is fundamentally flawed instead of just looking at reality?

Also, no baseline was defined there. It's a 100% relative piece of information. Broken glass has more entropy than unbroken glass. This is fact. It's like saying that the Sun has more mass than the Earth.

Yes, I know. But it's completely inconceivable that entropy functions in reverse, and that we're just forgetting the past? I don't know, it's probably pointless, almost certainly non-falsifiable, because we're going to experience it this way anyway, but it's interesting to me anyway. It's information gradually being removed from a system instead of created. Why shouldn't it work this way? What keeps it from working this way other than our expectations that the way we experience time is based on memories forming rather than being destroyed?

The fact that it's such a big thing for physicists to prove (or even just the fact that it warrants a great big wiki page attempting to prove it) is weird to me, because I can't see any way to do so without the assumption that observation isn't flawed. From my understanding of science, the stance for things like this is "don't even bother, it's philosophy"

It's about as useful a question as "what if everything was spiders?". Time being backwards to our perception means absolutely nothing to us, since clearly our observations wouldn't be different at all. It's an idea that doesn't create any testable predictions nor does it change anything we already know, so it's worthless.

[Eagleon]

Why would you assume that observation, even observation that doesn't directly involve humans, is fundamentally flawed instead of just looking at reality?

Also, no baseline was defined there. It's a 100% relative piece of information. Broken glass has more entropy than unbroken glass. This is fact. It's like saying that the Sun has more mass than the Earth.

Yes, I know. But it's completely inconceivable that entropy functions in reverse, and that we're just forgetting the past? I don't know, it's probably pointless, almost certainly non-falsifiable, because we're going to experience it this way anyway, but it's interesting to me anyway. It's information gradually being removed from a system instead of created. Why shouldn't it work this way? What keeps it from working this way other than our expectations that the way we experience time is based on memories forming rather than being destroyed?

The fact that it's such a big thing for physicists to prove (or even just the fact that it warrants a great big wiki page attempting to prove it) is weird to me, because I can't see any way to do so without the assumption that observation isn't flawed. From my understanding of science, the stance for things like this is "don't even bother, it's philosophy"

It's about as useful a question as "what if everything was spiders?". Time being backwards to our perception means absolutely nothing to us, since clearly our observations wouldn't be different at all. It's an idea that doesn't create any testable predictions nor does it change anything we already know, so it's worthless.

Right. That's about the response I expected. There are such things as ideas and valuations that aren't science, by the way, and they can stick around without hurting you or science.

But in the same way, why is proving that time moves forward meaningful to science? What testable predictions does it create? How is debating it not philosophy when we can't sit outside of it and observe it directly? I could just as easily say that time stands still and a giant phonograph needle is what's moving. That way nothing actually changes other than a position in the system. Why is this any better or more important than insisting that time exists the way we observe it?

[Angle]

Anyone been keeping up on that whole EMdrive thing? Has it been debunked yet, or is it still going strong?

I want my reactionless drives~...

[i2amroy]

Anyone been keeping up on that whole EMdrive thing? Has it been debunked yet, or is it still going strong?

I want my reactionless drives~...

I wouldn't be too optimistic, since you know, any true reactionless drive kinda violates the law of the conservation of momentum.

A quick glance at the wikipedia page for it reveals that there has yet to be anything published in peer-reviewed journals, nor has anyone replicated the results under standards high enough for the scientific community or been willing to share their "results" in peer-reviewed stuff yet.

[wierd]

To me, the more interesting question is "What happened to the past?"

We can accept as truth that in a closed system, entropy will always increase and not dissipate.
We can also hold as truth that information cannot be destroyed, only changed (made more entropic).

However, one of the features of information conservation is that information about the past is not lost irreparably.
(This was the big spark behind the black hole debates in the 70s.)

Depending on how you look at spacetime, the past and the future are just positions on a mathematical surface, which follows certain rules. This is why you can have such curious things as time being absurdly fast in one part of the universe, and infinitely slow inside others, when compared with a different point in space as a point of observation.

Since this means the concept of "Past", "Present", and "Future" are fuzzy in the greater scheme of things, this implies that traveling to a point that would logically be in the past relative to your own timeline is theoretically possible (But probably practically impossible, and if causality is to be obeyed, such travel would be in the past, but outside your light cone.)

To me, this suggests that "The past" is not "Lost", any more than say, the depressions in the groove of a record are lost, after the needle moves past.  Can you play the record backward? Not really. It's not designed that way.  Can you play the record over again? Why not?

In this thought experiment, "Time" is the action the spinning turntable has to turn the record underneath the needle.  the "Past" is the section of the groove that has already gone under the needle. the "Present" is the ephemeral point directly under the needle, and the "Future" is the portion of the groove yet to pass under the needle.  The relative forward velocity of the track under the needle changes as the spiral moves out from the center of the record, even though the turntable is turning at a fixed rate, due to changes in the distance traveled per rotation. This has some curious analogs with the space/time relationship.

In this way, "Time" is a real thing, which has real effects, but since the past is not actually lost, the actual state of the universe (the record) does not change. Our perception of the universe is what changes, as our reference point on the time axis changes, and the rules we observe prevent us from experiencing that axis backwards.

Philosophers HATE this kind of interpretation, because it makes free will into an illusion.  I on the other hand, like it-- it means that because I have existed in the past, I will always continue to exist as a past feature of the universe, and depending on the reference from which that universe is observed, I am always existing, and always will exist.

[ShadowHammer]

I understand the heat death.
Is it perhaps possible for heat energy to convert into another type of energy.
Like a heat eating spacewhale?

Does time exsist? I understand it and can see a watches hand moving but is time an actual force?

Spoiler (click to show/hide)

Sorry people.
I lived on a farm until I was 12 and then left highschool at 15.
Im not terribly book smart. I feel like I cant comunicate properly, like I cant translate my thinking into readable words. It can drive me crazy.

To answer the first question here, yes, heat can and is often converted directly into other forms of energy. A thermocouple takes heat and converts it directly into electricity.
This leads me to a question: if a gas has more entropy than a liquid, and you use a thermocouple to cool a gas down to the condensation point, and then proceed to use the resultant electricity to charge a battery, haven't you just decreased total entropy?
Note: I may not (read: don't) really understand how entropy works.

[Eagleon]

Stuff

Thank you <3 That's exactly what I was getting at. Just nitpicks that, in a universe which could be played backwards, your first two points would just have another two opposites in that domain. The information conservation rule for a universe in reverse would be a conservation of destruction - 'everything must go.' You'd 'forget' if a stationary time change happened, in fact if it were to start looping or got rolled backwards, no one would know but the DJ. Also, given a stereo channel, you could get some sweet phasing effects if you slightly offset the other univ- ok the metaphor has gone too far.

[Lagslayer]

So since it isn't all put together in an arbitrarily defined manner, it has more entropy? What if the glass is intended to be in small shards? Would that mean the properly formed glass has more entropy? It's not a simple matter of a baseline, it's also assuming a particular vector has more meaning. This means nothing on such a large scale.

No, it is not like saying the sun has more mass than the earth. That operates on the molecular level and smaller. It's comparing apples to pigeons. "Entropy" has no meaning unless it's a much smaller scale.

...Except that that's completely false. Entropy is "a measure of the number of specific ways in which a thermodynamic system may be arranged", which means that it applies to all closed systems, macroscopic or no. The statement "irreversible processes increase the combined entropy of the system and its environment" also means that breaking glass (which is an irreversible process) will always increase entropy.

Except that glass does not exist in a closed system.