What is the Fabric of Spacetime Made Of?

[JesseM]

I like you. You have made some interesting statements, something that contribues to the thread. You are articulate, and your communication is your own.

I think you said something about my antagonistic tone on this thread, your right, I will watch it.

You have mentioned many things that I would like to respond to, but it is getting late so I will have to respond later.

Thanks, I'm glad you didn't take my comments the wrong way, I'm critical of some of your main ideas and the dismissive way you often respond to opposing arguments, but I don't mean anything personal by this criticism. Take your time in thinking about my comments and responding.

 

[Saw]

Since I am quite fond of the subject, I’ve thought I should share some opinions:

I agree with John8 that time, space (and even motion, I would add) are just mind-made concepts, intellectual tools and they do not have physical existence.

I also agree with him that what does have physical existence is reality: some “actors” (let us call them like that in want of a better term) and their interactions.

Unfortunately, the features of the “actors” do not jump directly into your mind. You have to measure them. Measurement in turn is like organizing a competition between the actors and some other small actors (also real things) that you take as reference (let us call them the miniatures). Thus you can say that a number of the miniatures “are”, for the relevant purpose, the actor, because the former perfectly mirror or reflects the latter.

I would propose this metaphor: the height of a beautiful princess is measured against and found equal to the height of three ugly dwarves standing one on top of the other; once this is done, we can use the dwarves to check if a wedding dress is too long or too short for the princess; after that, the three dwarves escape and walk around mimicking the feminine gestures of the princess, pretending that they “are” the princess. Well, this is somehow true, as long as we do not forget that it is so for certain limited purpose (like checking if a dress will be too short or too long for the princess), but it is not for other purposes: if you are the prince of the tale, you would not like to marry the dwarves, even if you are a scientist, just because it has been “objectively measured” that the dwarves, if put one on top of the other, are as tall as the princess; likewise, you would not like to marry the dwarves, even if you are a mathematician, just because an equation states that 1 princess = 1 dwarf times 3. You would remember that the physical and mathematical “concept” that the dwarves mirror the princess is only valid for the purpose for which it was invented.

Thus I agree with most posters that concepts (like time) are to the essence of physic. That is the nature of things. Since we are ourselves physical things, we cannot try to ascertain what things are and what happens inside things without choosing a reference for comparison and talking “as if” the reference were the measured object. This is so true that, in fact, if you try to define reality in terms other than comparisons with other realities, you are doomed to failure. I myself in another thread have used the terms “particle or wave” as meaning the ultimate “building blocks” of reality. However, one can do this in order to make the argument that reality is something different from concepts, but cannot do so without admitting that “particles” or “waves” are themselves also concepts.

I also agree with other posters that physics is what is (it has reached an astonishing level of development) because it has waived the ambition to explain things in terms of what they intrinsically are and contented itself with the comparisons = competitions = observations = measurements = concepts, which are arranged in mathematical equations. The example of the Law of Universal Gravitation is very well brought and Newton’s assertion “I frame no hypothesis” as to why the formula is correct a good slogan of the trick.

But it must also be said that the formula in itself is a hypothesis that seeks a more fundamental explanation than previous formulations. Galileo’s formulas related to gravitation only dealt with the concepts (“mirrors”) of distance and time. Newton was bolder and made a hypothesis about why objects traverse certain distances in certain time lapses: there is an interaction between two masses and the strength of the interaction has to do with the quantity of mass of the objects involved in the interaction. That was a big progress and in fact, having this in mind enabled Newton to and guided him in his correction and improvement of Kepler’s laws, which were based on observations leaning exclusively on time and distance. Of course, mass itself is also a concept you measure in “competitions” between masses, but a concept that better mirrors what really happens in reality and thus a more powerful one.

Conclusions: yes, concepts are the essence of physics, but it is not out of question to remember from time to time that they are so, mere mirrors of reality that do their job only to the extent that we use them in accordance with their intrinsic logic. In particular, I don’t think it would be inappropriate to mention so in the prologue of physics textbooks…

 

[Dale]

Lets see here, you say time is not a wave. then you go to give a definition of a wave and say that time is part of this definition of a wave. O.K. Pause; I want to give you time to think about what you said.

Go ahead, I will allow you to really think about what you just said.

Maybe you should have a cup of coffee and go for a walk, clear your head.

Your rebuttal is not logical. Here is an analogy: a radio transmitter is not a cell phone. A cell phone is defined as a radio reciever and transmitter that interface with a cell tower and the phone system. A radio transmitter is not a cell phone even though a radio transmitter is an essential part of the definition of a cell phone.

Similarly time is not a wave, but time is an essential part of the definition of a wave.

You have now asked me to give my definition of a wave.

And you have avoided giving your definition yet again. This argument has been entirely semantic up to this point, so clearly defining your terms is essential. We cannot progress unless we each understand what the other means by these important terms. So I ask again, what are your definitions of "wave" and "energy"? I have given the standard physics definitions of "wave" and "energy", which are the definitions I use. Can you not do the same?

 

[Naty1]

Most people, fortunately, post questions and issues to gain an under standing from the point of view of best experimental and theoretical physics...Other just post to argue with such responses...it's clear who is who and the latter are neither worth the time nor will they learn if given the time...

 

[A.T.]

You have now asked me to give my definition of a wave.

I have given the standard physics definitions of "wave" and "energy", which are the definitions I use. Can you not do the same?

No, because he is using the definitions provided to him by "science". But which "science" might it be? Gender studies? Ornithology? Wait! He is invoking "science" & "logic". Maybe Scientology?

He's obvously http://www.youtube.com/watch?v=2IlHgbOWj4o".

 

[p764rds]

Gravity bends space, space-time is a math model only.

If space-time is a math model only, then it means that objects are all on top of each other and that the metrics ("space") are only parameters attached to objects that identify them uniquely from other objects. (or am I way out here?)

Is flat (no gravity) euclidean space possible at all outside of mathematics? (I don't mean by nesting it in another space). My opinion is that flat space is not possible outside mathematics- but I am not 100% sure. Someone told me the question has no meaning and is vacuous (no pun intended) because I need an object in the space - what's that all about?