What is spacetime made of?

This is not an everything goes forum, but rather a place to ask questions and request help for developing your ideas.

Re: Double Time

Postby Faradave on September 7th, 2018, 2:39 am 

ronjanec wrote:Why is N.Y.C pizza so lousy?

Ha! I'm not from THE Times Square, That's a reference to my thread of the same name, where I introduced interval-time coordinates.

You're aware of the relativistic expression "Moving clocks run slow." which leads to not ticking at all at limit c. This implies, geometrically independent paths to the future: maximally aging path (at rest) and non-aging (traveled by light). All speeds (including standing still) and all directions lead to the future. What varies is where you end up in space and how much you aged, (relative to the cosmos, as a universal reference).

Thus, it's the basis of a coordinate system, available to any observer, which happens to be Euclidean (just like high school geometry). The horizontal component represents what is termed a "spacetime interval" instead of space. Since it has the non-aging inclination that light assumes, I called it "improper time" to contrast it with the vertical "proper time" of SR.

Image

ronjanec wrote:I honestly cannot see any really good reason why time had to begin in the Big Bang

Assuming you accept a 4D continuum*, it boils down to this question. Can you accept one with an absolute center or do you prefer one with no particular center. Either can be infinite.

The separation from an absolute center is geometrically no different that a measure along some other direction. It can be called by any term that implies separation. I argue that the radial separation exists independent of man. But man has applied arbitrary means of measuring and naming it, just as I did with Times Square.

*You agreed that I'm separate from George Washington's birth by more than just 3D space, allowing for a 4th of "duration".
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Re: What is spacetime made of?

Postby ronjanec on September 7th, 2018, 6:40 pm 

Faradave,

Moving clocks run slow.”? Again Dave, this does not mean that naturally occurring time would slow down under the same conditions because this never existed in the first place! If a regular clock, or even an atomic clock slowed down in an (any) experiment, it just means that you need to find someone to fix the clock. :)

Yes, I agreed that you were also separated from G.W by duration: and duration is not a fourth dimension of anything, it is a property of something.

(All this time I thought you lived in the Times Square area Dave!)
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Re: What is the continuum made of?

Postby Faradave on September 7th, 2018, 7:35 pm 

ronjanec wrote:...duration is not a fourth dimension of anything, it is a property of something.

I'm willing to consider "age" as a property. Are you denying a 4th geometric dimension of separation?
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Re: What is spacetime made of?

Postby ronjanec on September 7th, 2018, 8:23 pm 

“Are you denying a 4th geometric dimension of separation?” I probably would if I knew what in the heck this was Dave. :)
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Re: The Secret of the Pyramids

Postby Faradave on September 8th, 2018, 12:27 am 

ronjanec wrote:4th geometric dimension of separation?” … if I knew what in the heck this was

I think you can know this.
The hypotenuse h of a right triangle with legs a & b is given by Pythagoras from:
h2 = a2 + b2
The hypotenuse h of a right pyramid with legs a, b & c is given by Pythagoras from:
h2 = a2 + b2 + c2
The hypotenuse h of a right hyper-pyramid with legs a, b, c & d is given by Pythagoras from:
h2 = a2 + b2 + c2+ d2
… and so on, for any number of dimensions.

Our brains don't consider visualizing 4D (& above) to be worth the cost, but the geometric progression is valid nonetheless. Physicists treat time as a 4th geometric dimension but they have an embarrassing problem. Pythagoras doesn't quite work unless a minus sign is introduced.

A 4D hypotenuse is a "spacetime interval" with the equation:
h2 = x2 + y2 + z2 - t2

Times Square is the result of moving t2 to the other side of the equation, which restores Pythagoras (i.e. Euclidean geometry).
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Re: What is spacetime made of?

Postby Positor on September 8th, 2018, 9:38 am 

ronjanec » September 7th, 2018, 11:40 pm wrote:Moving clocks run slow.”? Again Dave, this does not mean that naturally occurring time would slow down under the same conditions because this never existed in the first place! If a regular clock, or even an atomic clock slowed down in an (any) experiment, it just means that you need to find someone to fix the clock. :)

It is not just actual clocks. Anything that moves (except light) runs slow, including biological processes. An observer's own clock would appear to that observer to work normally (its ticks would be perceived to occur at the normal speed). But two observers, each moving relative to one another at a constant velocity, would each think the other's clock is running slow (even after compensating for the delay in receiving the information). This is not due to any defect in the clocks; it is due to relativistic effects.

ronjanec wrote:Yes, I agreed that you were also separated from G.W by duration: and duration is not a fourth dimension of anything, it is a property of something.

Then let's talk about "duration" instead of "time". Durations have existed since the big bang, and each of these durations had a magnitude, which could have been measured and called "time" if there had been anyone around to do so. But the magnitudes of the past durations really existed; one of them might (in one frame of reference) have been twice as long as another, or 4.263 times as long, or whatever. But these magnitudes are/were affected by relativity.

What is called "spacetime" (I suppose we could call it the "space/duration model" instead, if you want to avoid the word "time") is an abstract framework for relating the speeds, lengths and durations of real objects and events.
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Re: What is spacetime made of?

Postby Positor on September 8th, 2018, 8:52 pm 

ronjanec » September 8th, 2018, 9:26 pm wrote:But man just calling the magnitude or extent of duration of what is actually the particular property of something else existing in the universe “time” or “time existing” as the results of his measurement, still does not make what is again just called time or is again just called time existing from the results of man’s measurement, a naturally occurring distinct thing in the universe that could in any way be effected by any kind of relativity principle.

But why do you believe that the properties of actually existing things cannot be affected by relativity principles? Relativity is a real, observed phenomenon, not just a mathematical exercise, so one would expect it to apply to real things (objects and events and their properties).
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Re: What is spacetime made of?

Postby ronjanec on September 8th, 2018, 10:01 pm 

Positor » Sat Sep 08, 2018 6:52 pm wrote:
ronjanec » September 8th, 2018, 9:26 pm wrote:But man just calling the magnitude or extent of duration of what is actually the particular property of something else existing in the universe “time” or “time existing” as the results of his measurement, still does not make what is again just called time or is again just called time existing from the results of man’s measurement, a naturally occurring distinct thing in the universe that could in any way be effected by any kind of relativity principle.

But why do you believe that the properties of actually existing things cannot be affected by relativity principles? Relativity is a real, observed phenomenon, not just a mathematical exercise, so one would expect it to apply to real things (objects and events and their properties).


I am not saying that the properties of actually existing things cannot be effected by relativity principles Positor; I am saying that time cannot be effected by relativity principles because it does not exist in object form: it is again basically just a word that man uses to call and describe a number of different things existing and moving(or again, something else’s object existence or movement), and the results of his timekeeping system.

Again, the discussion here is about the possibility of time in particular being effected by relativity principles Positor: not are the properties of things in general effected by relativity principles.
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Re: What is spacetime made of?

Postby hyksos on September 9th, 2018, 3:11 am 

And I challenge anyone anywhere reading this, to point to any distinct physical object or thing existing anywhere in the universe that you are saying is time actually existing in distinct physical object or thing form(And please remember, this cannot be something else actually existing here in distinct physical object or thing form)

If you believe that Energy is a substance, then you must conclude that time is an object along with it. The only reason that Energy is conserved is due to the fact that the Laws of Physics do not change from moment to moment.

You could escape from this trap by giving up on the idea that capital-E Energy is a substance to begin with. But you have to read Noether's Theorem to see how to visualize that metaphysical stance. In any case, your challenge for us was to point to any distinct physical object or thing. I point my finger at the fact that energy cannot be created or destroyed, but is seen changing forms. If I drop a bowling ball from the 4th floor window, and it crashes on the sidewalk below, I can point at the heat generated by the friction of the impact, and ask you where that came from. You would say "Well that's easy. It came from the kinetic energy in the bowling ball." To some approximation you can account for heat and temperature as "the wiggling of atoms" and so this demonstration is unconvincing to you. That heat can be accounted for by molecular and atomic wiggling is a fine classical approximation. But that prejudice demands that all motion ceases at absolute zero temperature. That has shown to be false even with atoms. That prejudice also demands that the energy in empty space is flatly zero -- and it clearly is not.

The universe is not a machine of indivisible massive chunks. Mass can be converted to energy and vice-versa. If you model a massless cube with ideal perfect mirrors on its inside, and somehow beam some light energy inside that cube, it will act to outside observers as if it contains mass. This is not a mathematical trick. This exact reasoning explains the mass defect in nuclei. The missing mass is perfectly offset by the binding energy of the nucleons.

Raze(and anyone else reading this), I am not trying to prove the T.O.R wrong here(although, I again personally believe it to not be true):: I am only trying to prove the “time dilation” part of this theory wrong.

The observer in his space ship (coasting along at 0.999c) sees nothing wrong with the passage of time in his quarters on that ship. Everything is as it should be. The time dilation inside the ship is observed only by stationary observers watching the ship pass by.

In regards to time not being a real object, Albert Einstein wrote to a friend that any distinction between past, present and future is only a "stubbornly persistent illusion". But Einstein didn't really mean "time" there. He was really referring to the present moment. There is nothing in physics that says the present moment exists. No equations can capture it. Certainly Faradave's (-t2) does not depict a present snapshot -- a "now" remains elusive.

Some have taken the mystery of the Missing Now, and run with it down metaphysical rabbitholes. Those people conclude that the universe is a frozen 4-dimensional chunk, existing statically without change. What they call the "Block Universe".

If we don't mean The Present, and we instead prefer to concentrate on the passage of time itself, we can get a clue from the Wheeler-DeWitt equation. This equation results from combining General Relativity and Quantum Mechanics in a way that makes no ulterior assumptions. The resulting equation has no time in it because the time component literally cancels out. Carlo Rovelli's reaction to this oddity was ,

In classical canonical gravity, a spacetime can be represented as a ‘trajectory’ in configuration space – the space of all three-metrics... Since no trajectories exist anymore in quantum theory, no spacetime exists at the most fundamental level, and therefore also no time coordinates to parameterize any trajectory.

The question as to the meaning of the cancelled-out time has no consensus in physics. Some have suggested that it merely reiterates that all times are co-equal, in that there is no special time or preferred point in time. (analogous to no preferred Reference Frames in Special Relativity). I have my own opinions. But those opinions would be better expressed in Physics section, rather than in the penalty box that is Fringe theories and speculations
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Re: What is spacetime made of?

Postby Positor on September 9th, 2018, 7:34 am 

ronjanec » September 9th, 2018, 3:01 am wrote:I am not saying that the properties of actually existing things cannot be effected by relativity principles Positor; I am saying that time cannot be effected by relativity principles because it does not exist in object form: it is again basically just a word that man uses to call and describe a number of different things existing and moving(or again, something else’s object existence or movement), and the results of his timekeeping system.

OK, but can you clarify one point please. Do you believe that durations can be affected by relativity principles? (I thought you said in your previous post that they could not, but unfortunately that post has been deleted.)

If you regard 'time' as just a human system for measuring durations, then if durations (which are properties of existing things) are affected by relativity, 'time' is indirectly affected, since the measurements of the affected relative durations need to be recorded correctly.

What is spacetime made of? Is it "made of" anything physical, at the smallest scale? That is for physicists to answer - and it is why much of the discussion in this thread has involved detailed physics. But suppose it is not literally "made of" anything that you would regard as a physical entity. Then it would be an abstraction, but it would still be meaningful.

For example, consider 'length'. What is the length of a wooden bar "made of"? Wood? No, the object itself is made of wood. Length cannot be wooden; it is a property, not an object. ('Woodenness' is another property, but it would not make sense to say that woodenness is wooden.) Another example: what is the set of co-ordinates on a map "made of"? Nothing physical; it is just an abstract framework for identifying real places.

Even if spacetime is not "made of" anything physical in a straightforward sense, it can still indirectly refer to a real thing or things.
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Re: What is spacetime made of?

Postby ronjanec on September 9th, 2018, 9:38 am 

hyksos,

I have never been able to personally figure out if energy is an independent substance/distinct thing in and of itself, or if what is called energy is just a physical change of state of something else. What could the substance of energy in distinct physical object or thing form actually be made of?

The challenge is to again actually point to any distinct physical object or thing existing anywhere in the universe that you are saying is time actually existing here in distinct physical object or thing form(and this again can’t be something else actually existing here). You are not actually doing this with your comments about this hyksos.

Once again, for time to actually slow down(or time dilation) on the spaceship relative to earth, time must be a distinct physical object of some kind existing on the spaceship and also existing in the same way on earth(and I am again saying that this is not true) Time only exists on the spaceship because man talks and thinks about the same, and calls the ever changing and increasing results on his atomic clock time.

Again, time is basically just a word that man uses to describe the results of a particular type of measuring system that he invented many centuries ago: or what is called the timekeeping system.

“Time can’t exist as just a word man uses!?” No? Then point to something...anything that is actually time existing in distinct physical object or thing form, that is again not just a word man used for something else actually existing and moving here in distinct physical object or thing form. :)
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Re: What is spacetime made of?

Postby ronjanec on September 9th, 2018, 10:08 am 

Positor,

Do I believe that durations can be affected by relativity principles? No, I do not. Again, the word “duration” means the continued existence of a person, thing, or event: So we are actually talking about a state of existence or being here. You either exist...or you do not exist. Relativity cannot effect, whether or not someone or something exists.

And yes, some properties of individual things may be effected by relativity principles Positor, but again, not this particular type of of property.

(I will try to comment on the rest of your post when I have a little more time)
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Re: What is spacetime made of?

Postby davidm on September 9th, 2018, 11:28 am 

Ronjanec, do you carefully read what others write? Because for the most part, you don’t engage with the key points.

You maintain that time dilation does not exist. It’s empirically observed. It’s observed all of the, uh, time. Do you use a GPS? Are you aware that these things are programmed to take time dilation into account? The fact that they work properly is verification of time dilation right there. There are many other such verifications.

You claim that people are avoiding metaphysical discussions of time. Yet I gave you a link to a book chapter that is nothing but a discussion of the metaphysics of time, and space as well.

You keep saying that time must be some kind of physical substance for it to dilate. But it has been explained to you that in relativity, time is what clocks measure, and space is what rulers measure.

What slows down in a frame in motion relative to a stationary frame are all physical processes — and this IS time dilation. This has been explained to you as well.

Are you aware that in a frame at relativistic velocity, space shrinks in the direction of motion? This is called length contraction. Are you now going to argue that space does not exist, either? (In the linked chapter of Swartz’s book, he also argues that space does not exist — but means that it is not a substance. He gives a revised definition of space (and time) that I believe to be correct ones.

ETA: In the case of length contraction, what is shrinking, of course, isn’t space as such — not some “substance” called space — but the vehicle, and everyone and everything inside of it. This is precisely analogous to time dilation, which is the slowing of all physical processes, including clock ticks.
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Re: What is spacetime made of?

Postby hyksos on September 9th, 2018, 12:38 pm 

ronjanec » September 9th, 2018, 5:38 pm wrote:hyksos,

I have never been able to personally figure out if energy is an independent substance/distinct thing in and of itself, or if what is called energy is just a physical change of state of something else. What could the substance of energy in distinct physical object or thing form actually be made of?

The challenge is to again actually point to any distinct physical object or thing existing anywhere in the universe that you are saying is time actually existing here in distinct physical object or thing form(and this again can’t be something else actually existing here). You are not actually doing this with your comments about this hyksos.

Once again, for time to actually slow down(or time dilation) on the spaceship relative to earth, time must be a distinct physical object of some kind existing on the spaceship and also existing in the same way on earth(and I am again saying that this is not true) Time only exists on the spaceship because man talks and thinks about the same, and calls the ever changing and increasing results on his atomic clock time.

Again, time is basically just a word that man uses to describe the results of a particular type of measuring system that he invented many centuries ago: or what is called the timekeeping system.

“Time can’t exist as just a word man uses!?” No? Then point to something...anything that is actually time existing in distinct physical object or thing form, that is again not just a word man used for something else actually existing and moving here in distinct physical object or thing form. :)

Mass.

Vacuum fluctuations.

Energy.

Choose one or more according to taste.
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Re: What is spacetime made of?

Postby davidm on September 9th, 2018, 2:06 pm 

Ronjanec,

You seem to think that for something to be real, or to exist at all, it must be a physical substance of some kind.

Is the Pythagorean Theorem, mentioned earlier in this thread, a physical substance? No. It is a description of the properties of right triangles. But it is real for all that.

Are numbers physical substances? I can write numbers down on a sheet of paper, and now I have physical things — a sheet of paper and ink. But these jottings are not numbers — they are numerals. Numbers are ideas. Numerals are their physical, symbolic representations, their form a matter of pure convention. By your way of thinking, numbers — and hence math! — do not exist.

Is there a substance called space that lies between the earth and the sun? No, there is just the concept or idea of distance, which can be designated by units. Is there a substance called time that lies between the end of World War II and the present? No, there is just the concept or idea of duration, which can also be designated by units. A more precise way of stating these relations would be to say that there is a greater spatial distance between the sun and earth, than there is between the earth and moon. But these distances are not themselves things or substances, but relations among things and substances: earth, moon, sun. Similarly, there is a greater duration — a greater temporal distance — between the end of World War II and events and things that exist now, than there is between the events and things of yesterday, and those of today. It is the things that are physical, not the relations among them.
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Re: What is spacetime made of?

Postby curiosity on September 9th, 2018, 4:42 pm 

What is called "spacetime" (I suppose we could call it the "space/duration model" instead, if you want to avoid the word "time") is an abstract framework for relating the speeds, lengths and durations of real objects and events.



"The distance/duration model, I have adopted sounds better still !"
By using the speed of light as a common denominator, the three dimensions of distance that we refer to as space, can be given as durations,(Times) when added to the existing dimension we refer to as time (which is duration.) The result is four dimensions of duration. (time.)
Alternatively, by using the same common denominator the dimension we refer to as time can be given as a distance, which when added to the existing three dimensions of distance results in four dimensions of distance. (space) This principle is evident when we use the term light "year," to denote a distance, or give the international standard for a metre as 1/299,792,458 of a second.
I believe it is our senses that make the distinction between space and time, (distance/duration) whereas in reality there is no such distinction. They are a seperation in spacetime, not seperations in both space and time!
In an ideal universe a metre in one location would be exactly comparable in length to a metre in any other location. A second of duration would also be comparable to a second of duration in any other location. Unfortunately for most peoples ease of comprehension, this is not so... The presence of matter can warp spacetime, but the ratio of space to time always remains the same, thus making the speed of light appear the same for all observers.
As an atheist I dont believe in a supreme being/creator, but if I'm wrong.... That supreme being certainly has a sense of humour... To refer to the goings on in this instance of spacetime we exist within as being quirky, would be a massive understatement.
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Re: What is spacetime made of?

Postby Positor on September 9th, 2018, 8:58 pm 

ronjanec » September 9th, 2018, 3:08 pm wrote:Do I believe that durations can be affected by relativity principles? No, I do not. Again, the word “duration” means the continued existence of a person, thing, or event: So we are actually talking about a state of existence or being here. You either exist...or you do not exist. Relativity cannot effect, whether or not someone or something exists.

OK, let me rephrase my question: Do you believe that the magnitude/extent of durations can be affected by relativity principles? That is something that can be quantified, not just a question of whether something exists or not. It is a question of how long something lasts, or how long the interval is between two events.
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Re: What is spacetime made of?

Postby ronjanec on September 9th, 2018, 11:37 pm 

I somehow hit submit before I was finished: so please just ignore this, and read my next finished comment.
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Re: What is spacetime made of?

Postby ronjanec on September 9th, 2018, 11:55 pm 

davidm » Sun Sep 09, 2018 9:28 am wrote:Ronjanec, do you carefully read what others write? Because for the most part, you don’t engage with the key points.

You maintain that time dilation does not exist. It’s empirically observed. It’s observed all of the, uh, time. Do you use a GPS? Are you aware that these things are programmed to take time dilation into account? The fact that they work properly is verification of time dilation right there. There are many other such verifications.

You claim that people are avoiding metaphysical discussions of time. Yet I gave you a link to a book chapter that is nothing but a discussion of the metaphysics of time, and space as well.

You keep saying that time must be some kind of physical substance for it to dilate. But it has been explained to you that in relativity, time is what clocks measure, and space is what rulers measure.

What slows down in a frame in motion relative to a stationary frame are all physical processes — and this IS time dilation. This has been explained to you as well.

Are you aware that in a frame at relativistic velocity, space shrinks in the direction of motion? This is called length contraction. Are you now going to argue that space does not exist, either? (In the linked chapter of Swartz’s book, he also argues that space does not exist — but means that it is not a substance. He gives a revised definition of space (and time) that I believe to be correct ones.

ETA: In the case of length contraction, what is shrinking, of course, isn’t space as such — not some “substance” called space — but the vehicle, and everyone and everything inside of it. This is precisely analogous to time dilation, which is the slowing of all physical processes, including clock ticks.


Yes, I (usually) carefully read what others write davidm, unless they start out with a bunch of illogical nonsense.

I am not exactly sure how this all this works in relation to GPS systems, so I am not going to make an uninformed comment about this.

Yes, you posted some metaphysical comments in this thread, and phyti also posted some metaphysical comments in this thread, but generally speaking, the physics comments by far outnumber the metaphysical comments.

(And by the way, what’s it to you? You start out by preaching about what you believe are my personal reading habits, and now you’re preaching to me about my personal comments about the nature of others comments in this thread: Go preach to someone else ok?)

“But it has been explained to you that in relativity, time is what clocks measure, and space is what rulers measure”;

“time is what clocks measure”? No, it isn’t: Clocks are pre-programmed to actually measure(this is not an active measurement of course) the 360 degree rotational motion of the earth on its axis into synchronized intervals that are called seconds, minutes, and hours, or what man again also calls time existing and moving here(Atomic clocks are of course different in design, but they also do not actually measure time);

Contrary to what you and a number of others seem to personally believe here, time is not some kind of weird invisible thing flowing around the universe that clocks actually measure the movement of.

“space is what rulers measure”? No, rulers actually measure physical dimensions/sizes.

You’re really on a roll here davidm with your personal “knowledge” of time and space. You definitely need to spend some more personal time thinking about both things, before you try to inform others about either thing and how they relate to relativity principles.
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Re: What is spacetime made of?

Postby ronjanec on September 10th, 2018, 12:42 am 

hyksos » Sun Sep 09, 2018 10:38 am wrote:
ronjanec » September 9th, 2018, 5:38 pm wrote:hyksos,

I have never been able to personally figure out if energy is an independent substance/distinct thing in and of itself, or if what is called energy is just a physical change of state of something else. What could the substance of energy in distinct physical object or thing form actually be made of?

The challenge is to again actually point to any distinct physical object or thing existing anywhere in the universe that you are saying is time actually existing here in distinct physical object or thing form(and this again can’t be something else actually existing here). You are not actually doing this with your comments about this hyksos.

Once again, for time to actually slow down(or time dilation) on the spaceship relative to earth, time must be a distinct physical object of some kind existing on the spaceship and also existing in the same way on earth(and I am again saying that this is not true) Time only exists on the spaceship because man talks and thinks about the same, and calls the ever changing and increasing results on his atomic clock time.

Again, time is basically just a word that man uses to describe the results of a particular type of measuring system that he invented many centuries ago: or what is called the timekeeping system.

“Time can’t exist as just a word man uses!?” No? Then point to something...anything that is actually time existing in distinct physical object or thing form, that is again not just a word man used for something else actually existing and moving here in distinct physical object or thing form. :)

Mass.

Vacuum fluctuations.

Energy.

Choose one or more according to taste.


Are you saying that they are all answers to the question what exactly is energy?

Again hyksos, I have been trying to figure out for quite awhile if “energy” actually exists as a distinct thing independent of physical matter, or if this is just a change of physical state of existing matter, and energy has no distinct independent existence of it’s own in the universe.

If it does have a distinct physical existence of it’s own independent of physical matter, what could it possibly be made of?
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Re: What is spacetime made of?

Postby ronjanec on September 10th, 2018, 1:20 am 

Positor » Sun Sep 09, 2018 6:58 pm wrote:
ronjanec » September 9th, 2018, 3:08 pm wrote:Do I believe that durations can be affected by relativity principles? No, I do not. Again, the word “duration” means the continued existence of a person, thing, or event: So we are actually talking about a state of existence or being here. You either exist...or you do not exist. Relativity cannot effect, whether or not someone or something exists.

OK, let me rephrase my question: Do you believe that the magnitude/extent of durations can be affected by relativity principles? That is something that can be quantified, not just a question of whether something exists or not. It is a question of how long something lasts, or how long the interval is between two events.


You want to rephrase your question?

So I spend a good amount of my personal time giving you a very thorough and concise answer to your original question, and now, without any comment from you whatsoever about my answer to your again original question , you expect me to spend even more of my time answering your new rephrased question? You’re kidding right? I am not going to waste any more of my time responding to you again about this Positor..
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Re: What is spacetime made of?

Postby Positor on September 10th, 2018, 8:29 am 

ronjanec,

I quoted part of your answer. My last post was a comment on it.

ronjanec » September 10th, 2018, 6:20 am wrote:you expect me to spend even more of my time answering your new rephrased question?

It is not a new question - it is a clarification of my original question, which you misunderstood.

When I talk about "duration", I mean not the mere fact that something lasts, but how long it lasts. I mean duration as a quantity. Do you believe that that is affected by relativity principles?
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Re: What is spacetime made of?

Postby davidm on September 10th, 2018, 9:42 am 

ronjanec » September 9th, 2018, 9:55 pm wrote:
Contrary to what you and a number of others seem to personally believe here, time is not some kind of weird invisible thing flowing around the universe that clocks actually measure the movement of.


And this, of course, is why I question how well you read what we write. We are saying just the opposite of this — that there is NO SUCH THING as time being a “weird invisible thing flowing around the universe that clocks actually measure the movement of.” How in the world did you derive this from anything that I, or anyone else here, actually wrote?

Instead of lecturing me about lecturing you about how to read my posts, go back and reread what I actually wrote about this topic. I specifically said that time is NOT a “physical thing” — did you read my post on the ontology of numbers, maths, and the Pythagorean Theorem?
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Re: What is spacetime made of?

Postby Braininvat on September 10th, 2018, 9:48 am 

Let's start with Karl Popper: "The natural numbers are the work of men, the product of human language and of human thought."

Now Karl isn't saying that numeracy isn't REAL. He would agree, I think, that a natural number may correspond to a state of affairs in the world. "There are nine hot dogs on the table." Of all the natural numbers, the positive integers seem especially anchored in our mundane sense of numeracy.

Now what if we are referring to a process of physical change in the world? We could paraphrase Karl and say "The minutes are the work of men... " Sure. Suppose we say "It took 15 minutes to cook those hot dogs on the table. " Would you agree that the rate of change, to change a hot dog from uncooked to cooked, is a real aspect of the world? And that, say if we use a certain uniformly made brand of hot dog, the rate of change is fairly constant with respect to other physical changes in the world, like the earth's rotation. 1/96 of a rotation will cook a hot dog. Even if no one were on the planet, this ratio could hold as a valid one regarding physical change. Everyone is Raptured off the earth, and those final pots of hot dogs still take 1/96 of a rotation. We call this sort of state of affairs, which can be numerically described, erm, "time. "

And, if an alien anthropologist studying Terran cookery zooms by at half lightspeed, and is somehow able to watch a pot of hot dogs, there will be a relativistic time dilation such that the hot dogs will cook somewhat more slowly from his perspective , perhaps in 17 minutes instead of 15. (sorry, didn't take time to call up my Lorentz transformation calculator) Again, these numbers and units correspond to a real state of affairs. This is what we mean when we say time is a real phenomenon.

Hope that helps.
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Re: What is spacetime made of?

Postby davidm on September 10th, 2018, 9:59 am 

ronjanec » September 9th, 2018, 9:55 pm wrote:
I am not exactly sure how this all this works in relation to GPS systems, so I am not going to make an uninformed comment about this.


Real-World Relativity: The GPS Navigation System


To achieve this level of precision, the clock ticks from the GPS satellites must be known to an accuracy of 20-30 nanoseconds. However, because the satellites are constantly moving relative to observers on the Earth, effects predicted by the Special and General theories of Relativity must be taken into account to achieve the desired 20-30 nanosecond accuracy.

Because an observer on the ground sees the satellites in motion relative to them, Special Relativity predicts that we should see their clocks ticking more slowly (see the Special Relativity lecture). Special Relativity predicts that the on-board atomic clocks on the satellites should fall behind clocks on the ground by about 7 microseconds per day because of the slower ticking rate due to the time dilation effect of their relative motion [2].


Do you own a smartphone or a car? If so, you are very likely taking advantage of a device that must, to function properly, take into account that very time dilation you deny exists!

As the article explains, GPS must take general relativity into account as well.

ETA: Hmm, has the "thank post" function been removed?
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Re: What is spacetime made of?

Postby davidm on September 10th, 2018, 10:11 am 

ronjanec » September 9th, 2018, 9:55 pm wrote:
Contrary to what you and a number of others seem to personally believe here, time is not some kind of weird invisible thing flowing around the universe that clocks actually measure the movement of.


And here is what I actually wrote, just upthread:

Is there a substance called space that lies between the earth and the sun? No, there is just the concept or idea of distance, which can be designated by units. Is there a substance called time that lies between the end of World War II and the present? No, there is just the concept or idea of duration, which can also be designated by units. A more precise way of stating these relations would be to say that there is a greater spatial distance between the sun and earth, than there is between the earth and moon. But these distances are not themselves things or substances, but relations among things and substances: earth, moon, sun. Similarly, there is a greater duration — a greater temporal distance — between the end of World War II and events and things that exist now, than there is between the events and things of yesterday, and those of today. It is the things that are physical, not the relations among them.
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Re: What is spacetime made of?

Postby davidm on September 10th, 2018, 10:23 am 

Braininvat » September 10th, 2018, 7:48 am wrote:And, if an alien anthropologist studying Terran cookery zooms by at half lightspeed, and is somehow able to watch a pot of hot dogs, there will be a relativistic time dilation such that the hot dogs will cook somewhat more slowly from his perspective , perhaps in 17 minutes instead of 15. (sorry, didn't take time to call up my Lorentz transformation calculator)


Yep, that seems almost exactly correct. Pretty good without your calculator. :-)
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Re: What is spacetime made of?

Postby hyksos on September 10th, 2018, 10:39 am 

Are you saying that they are all answers to the question what exactly is energy?

Special Relativity is not just a statement about time dilation. The very same theory relates energy and mass in deep fundamental ways.
emcsquarednecklace.jpg

https://www.chegg.com/homework-help/definitions/mass-defect-204

Again hyksos, I have been trying to figure out for quite awhile if “energy” actually exists as a distinct thing independent of physical matter, or if this is just a change of physical state of existing matter, and energy has no distinct independent existence of it’s own in the universe.

Many people have already walked the path you are on now. I have mentioned Noether's Theorem already. It is deeply related to these questions you are asking. But also, Special Relativity is deeply related to them. Special Relativity can be formulated by asking if we can place batteries and magnets on moving platforms and use those batteries to heat up a black body radiator. Then move these items around in such a way that we could harvest limitless energy. It is a question worthy of investigation. It would be nice for everyone if we could place magnets on moving platforms and build a limitless energy device.

But we can't. But more importantly we would ask : why not? The answer is Special Relativity. Mass and energy are equivalent and one scales at the speed of light squared versus the other.

If it does have a distinct physical existence of it’s own independent of physical matter, what could it possibly be made of?

If you study Special Relativity at the collegiate level, they formulate the mathematics in terms of 4-vectors. Then you can perform all the calculations you would ever need using a matrix that contains the Lorentz factor. You just slavishly multiply this matrix by the 4-vectors and all the answers pop out. It is possible, that late at night, when you are pounding the problems hard in preparation for an exam, you get into this 'mental zone' where it all suddenly makes sense. Like a kind of meditative state where you see the "big picture" as the wee hours come onto the clock after midnight.

It hits you unexpectedly, and you feel like you don't need to study anything anymore because it all makes sense and nothing the professor could throw at you on the midterm would catch you off guard. This state of "being woke" (lets call it) is like an inkling in the back of your mind. You close your notebook. You put away your books. There is nothing else to learn because your sensei can teach you nothing more. You have risen above the clouds and seen how it all fits.

It goes :

The universe is a 4-dimensional manifold, and we humans experience the 4th dimension as energy.
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Re: What is spacetime made of?

Postby ronjanec on September 10th, 2018, 10:51 am 

Positor » Mon Sep 10, 2018 6:29 am wrote:ronjanec,

I quoted part of your answer. My last post was a comment on it.

ronjanec » September 10th, 2018, 6:20 am wrote:you expect me to spend even more of my time answering your new rephrased question?

It is not a new question - it is a clarification of my original question, which you misunderstood.

When I talk about "duration", I mean not the mere fact that something lasts, but how long it lasts. I mean duration as a quantity. Do you believe that that is affected by relativity principles?


It was very late at night when I responded to your last comment and yes Positor....you did make a small comment about my answer to your earlier question. My mistake.

“which you misunderstood” No, I did not misunderstand your original question in any way shape or form: I answered it (correctly) in exactly the way that it should have been and how it was presented to me. You screwed up by not phrasing your original question properly the first time.

I have gone through this kind of thing with you a number of times in the past Positor, and I have “called you on the carpet” about this very thing a number of times in the past;

I make a comment, you ask me a question about this: I respond to your question and you never make a comment if I was right about what I just said and you then go on and ask me another question. I answer this question and the same thing happens over and over again until you finally just disappear from the thread and never acknowledge if I was right about anything or you were wrong about anything.

The real reason that you are doing this, or even responding to my thread in the first place, is due to the fact you have never been able to prove me wrong about anything in the past, and you are still really pissed off about this, and just keep trying to prove me wrong about something over and over again.

Well, hooray and hallelujah Positor! You finally caught me in a mistake! It was again very late at night, and I was really tired when I responded to your post (incorrectly) about you again “not commenting” about my post.

You will of course deny this, but we both know that this is exactly what has been going on here for a number of years Positor. You have not done this to me in quite awhile, and I tried to again respond to you hoping that you had changed your ways, but it looks like you have caught me in still another mistake in doing this.
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Re: What is spacetime made of?

Postby ronjanec on September 10th, 2018, 11:24 am 

davidm » Mon Sep 10, 2018 7:42 am wrote:
ronjanec » September 9th, 2018, 9:55 pm wrote:
Contrary to what you and a number of others seem to personally believe here, time is not some kind of weird invisible thing flowing around the universe that clocks actually measure the movement of.


And this, of course, is why I question how well you read what we write. We are saying just the opposite of this — that there is NO SUCH THING as time being a “weird invisible thing flowing around the universe that clocks actually measure the movement of.” How in the world did you derive this from anything that I, or anyone else here, actually wrote?

Instead of lecturing me about lecturing you about how to read my posts, go back and reread what I actually wrote about this topic. I specifically said that time is NOT a “physical thing” — did you read my post on the ontology of numbers, maths, and the Pythagorean Theorem?


You said “clocks measure time”, and you meant this literally;

Can anyone see this time you believe clocks measure? No, and that would also equal and imply time being an invisible thing. What would the same clocks literally measure? The implied rate of movement of the invisible thing.

So what you were saying here implied just what I said earlier without you even realizing what you were implying. That’s how I derived this.

What happened to your goofy comment about what rulers actually measure? No comment back on this?
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