Time

[Speakpigeon]

We don't think of past and future times as existing in the same way as the present moment.

Some people do. I do. At the very least, I don't see why I shouldn't.

Maybe you do entirely in the abstract, following your familiarity with Relativity.

But I doubt very much you could possibly have a sense of time that would have the past existing in the same way that it represents the present as existing. That's not even a rational consideration to have.

And we think we can move from one place to another every way we fancy but we couldn't move from now to yesterday or from now to two centuries from now, certainly not as we please.

This is the real difference. But the situation is strangely symmetrical between time and space:

In order to change our position in any of the first three dimensions, we must also change our position in the fourth. To counterbalance this restriction, we can travel in the first three dimensions at varying rates and directions.

We do not have to change our position in any of the first three dimensions in order to change our position in the fourth. To counterbalance this lack of restriction, we can only travel in the fourth dimension at a constant rate and direction.

Why dimensions 1-3 and 4 are juxtaposed in such a particular way is unknown. The equations of relativity don't require this juxtaposition. If this is all that you mean when you say "there's a contradiction between the block universe concept in Relativity and our subjective experience of time", then we agree.

Yeah and this very contrived "structure" of space-time you describe suggests to me that time isn't a kind of spatial dimension.

More generally, there's no good reason to believe that reality is really like our perception of it, or exactly like our mathematical models of it.
All we need is no apparent contradiction. And when we find one, we change our models.
EB

 

[skepticalbip]

Maybe you do entirely in the abstract, following your familiarity with Relativity.

But I doubt very much you could possibly have a sense of time that would have the past existing in the same way that it represents the present as existing. That's not even a rational consideration to have.

I have to disagree. Everyone’s subjective experience is shaped by and based on their mental picture of “reality”. One person observing the Sun will “subjectively experience” it as it is now. Another person observing the Sun will “subjectively experience” it as of eight minutes ago.

And we think we can move from one place to another every way we fancy but we couldn't move from now to yesterday or from now to two centuries from now, certainly not as we please.

This is the real difference. But the situation is strangely symmetrical between time and space:

In order to change our position in any of the first three dimensions, we must also change our position in the fourth. To counterbalance this restriction, we can travel in the first three dimensions at varying rates and directions.

We do not have to change our position in any of the first three dimensions in order to change our position in the fourth. To counterbalance this lack of restriction, we can only travel in the fourth dimension at a constant rate and direction.

Why dimensions 1-3 and 4 are juxtaposed in such a particular way is unknown. The equations of relativity don't require this juxtaposition. If this is all that you mean when you say "there's a contradiction between the block universe concept in Relativity and our subjective experience of time", then we agree.

Yeah and this very contrived "structure" of space-time you describe suggests to me that time isn't a kind of spatial dimension.

No, time isn’t a spatial dimension… according to relativity, it is a temporal dimension intimately interconnected with the three spatial dimensions.

More generally, there's no good reason to believe that reality is really like our perception of it, or exactly like our mathematical models of it.
All we need is no apparent contradiction. And when we find one, we change our models.
EB

Quite true for science. However, it seems that most people simply reject any contradictions to their mental picture of reality.

 

[Treedbear]

... We don't think of past and future times as existing in the same way as the present moment. ...

Just a thought, but if the present exists in time it's an infinitely small amount of time. If something is infinitely small can we claim that it actually exists? ...

Or not. Maybe time, if it does exist as such, is quantified. Why not?

Our sense of time doesn't help here but the present does not seem infinitely small to me, although I guess it wouldn't appear so even if it was in reality.
...

You've got me on that one. So now we have a QM explanation for the subjective experience of time along with our QM explanation for the subjective experience of consciousness and free will. Wonderful.

 

[Speakpigeon]

Maybe you do entirely in the abstract, following your familiarity with Relativity. But I doubt very much you could possibly have a sense of time that would have the past existing in the same way that it represents the present as existing. That's not even a rational consideration to have.

I have to disagree. Everyone’s subjective experience is shaped by and based on their mental picture of “reality”.

Yes, I agree. Not exactly that I would know this to be the case but that's definitely what I believe.

One person observing the Sun will “subjectively experience” it as it is now. Another person observing the Sun will “subjectively experience” it as of eight minutes ago.

Only the second option makes sense to me if by that you mean that we see the Sun as it was eight minutes ago.

How anybody located on the Earth could possibly experience subjectively the Sun as it really is now?

We take our subjective experience to be now. It's our reference for what is now. And we don't have a choice in the matter. The best we can do about our past subjective experience is to recall it from memory, although I guess a few people might well have some medical condition affecting this. But the light coming from the Sun takes eight minutes to get to us on Earth and so I don't see how the first option could be possible at all.

Yeah and this very contrived "structure" of space-time you describe suggests to me that time isn't a kind of spatial dimension.

No, time isn’t a spatial dimension… according to relativity, it is a temporal dimension intimately interconnected with the three spatial dimensions.

Sure, but the block universe view effectively removes the fundamental distinction we cannot help but make subjectively between time and space.

More generally, there's no good reason to believe that reality is really like our perception of it, or exactly like our mathematical models of it.
All we need is no apparent contradiction. And when we find one, we change our models.
EB

Quite true for science. However, it seems that most people simply reject any contradictions to their mental picture of reality.

Most people? You count yourself in?
Don't be so harsh with humans.
EB

 

[Speakpigeon]

Just a thought, but if the present exists in time it's an infinitely small amount of time. If something is infinitely small can we claim that it actually exists? ...

Or not. Maybe time, if it does exist as such, is quantified. Why not?

Our sense of time doesn't help here but the present does not seem infinitely small to me, although I guess it wouldn't appear so even if it was in reality.
...

You've got me on that one. So now we have a QM explanation for the subjective experience of time along with our QM explanation for the subjective experience of consciousness and free will. Wonderful.

Once you have an explanatory horse you can whip it hard for it to go as far as it can.

But I in fact didn't have QM per se in mind, only quantification.
EB

 

[Malintent]

But that's the "is" of predication, not the "is" of identity. We can explain time in terms of measuring movement, but time at its core is something else.

Perhaps, perhaps not.. That is part of this discussion. Is Distance "something else at its core", other than a comparison of two positions? Is Velocity "something else at its core", other than rate of change of position? Why is time "something more"?

There is a calculable distance between two positions. I know this. You know this. Whether there is such a thing as distance is not up for debate. If I take away your ability to calculate distance, the next step isn't to question whether there is distance. How much distance, maybe, but not whether there is such a thing as distance.

OK. I'm following....

If you cut on the faucet in the sink and water pours out, you can measure the water with the only available means to you, the measuring cup, but if I take that measuring cup from you, the wrong question is, "but how do I know there is water." You may ask the question, how much water is flowing but not whether water is flowing.

... but you can measure how much water is flowing without a measuring cup (stopwatch)... using the other "pieces of time" (distance and speed). You can use a ruler to measure the hole water is coming out of, and already knowing the pressure of the water, calculate rate of flow through the hole. You can use a pressure sensor to measure the force of water flowing through the hole, and already knowing the size of the hole, determine the rate. V = D/T... or, Water = Stream / Rate.
Time is meaningless without speed and distance, and it is my position that it does not even exist at all... no more than "an inch" exists. Time is a comparison of different things.

Time is something we can measure

Or... in my view.. Time IS measure (of change of position). Time is not a representation of a thing's attribute, like position. Time is a measure like distance.

, so you should have little doubt as to the existence of time, but such doubt shouldn't manifest with a thought experiment with the absence of our ability to measure it. Doubt how much time has passed, sure, but not whether there is time at all.

The idea whether there is time at all is akin to asking if there is room in a closet to put a box. Whether there is or isn't, space exists.

Time is not a concrete object, so it makes sense we speak of it in terms that we can understand, but we have to be careful not to deny the existence of something when we take away the means that help us make sense of it. If each tick of time is equivalent to a constant second that cannot waver in duration, then popping everything out of existence whereso no movement that allows for the measurement of time may lead us to experience time as it has stood still,

YES!

but the duration is still a function of the elapsed ticks from when moving objects are popped back in again.

NO!

So yes, time is something we measure, but where there can be no measurement does not imply no existence of time.

So, we have weaved space and time together, and then set speed at a constant (C). We call this spacetime.. .we change position though spacetime. It is useful for describing a 3 dimensional coordinate system.
There is no reason that I can see that we cannot just fix distance, and weave together speed and time. Speedspace.. we change time though speedspace. This is relativity. Lastly, we can create Speedtime, by fixing time and weaving distance and speed together. Somehow, the relevance of inertia and momentum is on the tip of my brain with this part, but a clear perception of this idea is beyond me.

 

[steve_bank]

Rulers and clocks are human inventions to objectively quantify change. It is as simple as that. Anything else is psychology and subjective metaphysics.

The problem with philosophy is there are no quantifiable reference points.

Time is defined scientifically by the Systems International second.

 

[steve_bank]

Regardless how we define distance and time, the two are linked.To move a move 1 meter requires time.

Until Albert's bombshell space and time were thought to be fixed. The key is to realize there are no absolute reference points. We can only measure something as a difference to an arbitrary reference. A 5 pound bag of potatoes is relative to the mass standard, a chunk of metal in a lab.

 

[lpetrich]

Time is defined scientifically by the Systems International second.

That's for physical time, and it does not say anything about how our consciousnesses are related to it.

There is an additional problem with time: the Second Law of Thermodynamics. It states that overall entropy never decreases. However, entropy in localized areas can decrease if that decrease is powered by increases in entropy elsewhere. Entropy is proportional to the logarithm of the number of microstates in a macrostate. It increases because it is more probable to to a macrostate with more microstates than fewer microstates. This means that the Universe started out in a low-entropy state and its entropy has been increasing ever since.

For analogies, consider an ant crawling on a sidewalk. It is more likely to be on a sidewalk square than in a sidewalk crack. So if the ant starts in a crack, it will move into the square, a seemingly one-directional move.

Also consider a refrigerator. By cooling its interior, it decreases its interior's entropy. But it does so at the expense of heating up its surroundings, increasing the entropy of those surroundings.

Could the direction of increase in entropy be connected with the our perceived direction of time? We need to be powered by increases in entropy, so there may be some conneciton.

 

[Speakpigeon]

Time is defined scientifically by the Systems International second.

That's for physical time, and it does not say anything about how our consciousnesses are related to it.

There is an additional problem with time: the Second Law of Thermodynamics. It states that overall entropy never decreases. However, entropy in localized areas can decrease if that decrease is powered by increases in entropy elsewhere. Entropy is proportional to the logarithm of the number of microstates in a macrostate. It increases because it is more probable to to a macrostate with more microstates than fewer microstates. This means that the Universe started out in a low-entropy state and its entropy has been increasing ever since.

For analogies, consider an ant crawling on a sidewalk. It is more likely to be on a sidewalk square than in a sidewalk crack. So if the ant starts in a crack, it will move into the square, a seemingly one-directional move.

Also consider a refrigerator. By cooling its interior, it decreases its interior's entropy. But it does so at the expense of heating up its surroundings, increasing the entropy of those surroundings.

Could the direction of increase in entropy be connected with the our perceived direction of time? We need to be powered by increases in entropy, so there may be some conneciton.

Sounds like a winner to me.

Is that really the case that there is no scientific interpretation of time around this idea? Not even the beginning of one? I don't know, from Penrose for example?
EB

 

[Malintent]

Time is defined scientifically by the Systems International second.

That's for physical time, and it does not say anything about how our consciousnesses are related to it.

There is an additional problem with time: the Second Law of Thermodynamics. It states that overall entropy never decreases. However, entropy in localized areas can decrease if that decrease is powered by increases in entropy elsewhere. Entropy is proportional to the logarithm of the number of microstates in a macrostate. It increases because it is more probable to to a macrostate with more microstates than fewer microstates. This means that the Universe started out in a low-entropy state and its entropy has been increasing ever since.

For analogies, consider an ant crawling on a sidewalk. It is more likely to be on a sidewalk square than in a sidewalk crack. So if the ant starts in a crack, it will move into the square, a seemingly one-directional move.

Also consider a refrigerator. By cooling its interior, it decreases its interior's entropy. But it does so at the expense of heating up its surroundings, increasing the entropy of those surroundings.

Could the direction of increase in entropy be connected with the our perceived direction of time? We need to be powered by increases in entropy, so there may be some conneciton.

Sounds like a winner to me.

Is that really the case that there is no scientific interpretation of time around this idea? Not even the beginning of one? I don't know, from Penrose for example?
EB

I don't know... Do clocks work differently inside versus outside a refrigerator?
This is still a relativistic reference to time, and not a definition of some 'thing'... it is no different from saying that time is the direction of entropy (a very elegant statement, by the way) to say that time is the ratio between distance and speed.

 

[Elixir]

Do clocks work differently inside versus outside a refrigerator?

Quarts clocks run faster when they are cooler - to a point. Cooler temps make the quartz crystal contract, raising its oscillation rate, so it records more oscillations per actual second. I've actually seen that effect in my truck's (which I park outside) clock, summer vs winter.
That's not what you were asking though... sorry for the thread drift!

 

[fast]

Time is not measure. It's something we can measure, but it's not itself measure. Time is independent of measure.

 

[steve_bank]

We measure change using a construct called the second. Philosophy vs science. '"What is time" is a meaningless unanswerable proposition.

 

[fast]

We measure change using a construct called the second.

Yes we do, and we do it well. If there is no change in movement, then we won't be measuring the time that continues.

 

[Malintent]

Time is not measure. It's something we can measure, but it's not itself measure. Time is independent of measure.

Anything that can be measured must be independent of the measuring tool. Time is the measuring tool, not the thing being measured... the thing being measured is that which has had a (relative) change in position (or change in entropy... I really like that.. going to keep going back to that). So, I am in disagreement that time is anything different than distance or speed. Does speed "exist"? does distance "exist"? why is time different than either of those forms of measurement?

 

[Malintent]

Regardless how we define distance and time, the two are linked.To move a move 1 meter requires time.

Until Albert's bombshell space and time were thought to be fixed. The key is to realize there are no absolute reference points. We can only measure something as a difference to an arbitrary reference. A 5 pound bag of potatoes is relative to the mass standard, a chunk of metal in a lab.

It's worse than that even... it actually takes an infinite amount of time to move 1 meter.... because, before you can possibly move 1 meter, you first have to move 1/2 meter... presumably, that will take half the time. Before you can move across the second half of that meter, you will first need to make it halfway... another 1/4 meter... that will take another quarter of the time.... since you can infinitely divide the distance to travel in half, and still have half of the last interval to travel, you can really never get anywhere in this universe!

 

[Malintent]

We measure change using a construct called the second.

Yes we do, and we do it well. If there is no change in movement, then we won't be measuring the time that continues.

I think we do it extremely poorly... the passage of time is experienced very subjectively.. also, there is movement of all matter.. all of the particles that make up the thing you want to call "moving" are themselves moving... so time is still measurable based on movement.

 

[steve_bank]

Time is a clock. If not, then define what you mean.

Time is a fart in the wind....

Way back in the 90s I rode a motorcycle when I lived in Portland Or. I liked to ride on Sauvie Island,' As I accelerated the centerlines blurred, at around 70 mph on a long straightaway my perceptions went into a slow mo mode. I could clearly see each line as I passed.

One day I entered a curve I had done many times. I noticed I was going sideways, gravel on the road. I watched the spill develop in slo mo detail. Right out of a movie slo mo. Perception of rate of change is a function of our physical brains. as is our consciousness.

As to clocks, all things mechanical and electrical vary with temperature. That is not relativity. The accuracy of a quartz based clock is relative to the national time standard.

 

[Elixir]

It's worse than that even... it actually takes an infinite amount of time to move 1 meter...

Tell it to this guy: