Another question on Gravity

[Shaw]

...Ergo my question; what IS IT made of? Rather than looking for a metaphor that suffices merely to describe the effect of space/time, I'm wondering on a a FUNDAMENTAL level--what is it?

Funny thing is, right now, our understanding has us using mixed mathematical constructs to explain it. The four dimensions that we are most familiar with seem to be modeled best with common ideas of geometry and topology. But then in the effort to unite our understanding of other aspects we've introduced group like dimensions that exist like fiber bundles over normal space-time.

And here is the thing that people really shouldn't forget... physics isn't reality. Physics is the best representation of reality that we've been able to put forward so far. But it is still just a mathematical representation and not reality itself.

The fact that matter-energy has a direct relation to the geometry of space-time and that inertial reference frames are all related by the speed of light rather than a stationary reference are realizations that are still having a hard time permeating the general public. Matter-energy may just be another state of space-time for all we know. But because it is the canvas on which everything else is painted, it makes it hard to describe as a product of something else. It is, and it seems that everything else follows because of it.

And the fact that it is still quite the mystery is what makes it a really enjoyable topic to study for me.


Edit:

P.S. "We don't know" is an acceptable and legitimate response.

We don't know.

 

[Christopher]

If there were ACTUALLY "nothing" between "here" and "there", I should be able to TRAVEL between "here" and "there" instantaneously. I would, in effect, BE both "here" and "there" simultaneously. But I am not. Time and energy must be expended to travel from "here" to "here". Thus, space/time is DEFINATELY a "something" as it effects (and actually DEFINES) our reality. Whatever space/time may be, it is not TANGIBLE to our senses; we see only the EFFECT it has upon us. But it is definately very real.

Ergo my question; what IS IT made of? Rather than looking for a metaphor that suffices merely to describe the effect of space/time, I'm wondering on a a FUNDAMENTAL level--what is it?

I don't think it's "made of" anything. I think it's just about as fundamental as you can get. Space is defined by motion over a period of time; time is defined by motion through space; motion is defined by space and time. They're all interlinked, inseparable qualities. They're "made of" each other.

Perhaps one can define it in terms of energy potentials. We can't travel instantly to another point because it requires energy to reach that other point, and that energy must be applied over time, which is the time it takes to travel there (or to accelerate to a velocity allowing you to coast there, and then to decelerate at the end).

So maybe one could say that space is a manifestation of the potential difference between objects. Ultimately it all boils down to energy.

 

[Zachary Smith]

Thanks for both responses. Stuff worth considering. It's frustrating sometimes when I see descriptions of the effect of something confused with the definition of the "something" itself. "It does this and we see that" etc. no, No NO! What IS IT? Not "what does it do"!

As I said, space/time is intangible to our senses. We see only the effect it has upon our universe (and, yes, I understand that sapce/time actually both effects and IS our universe). It ultimately becomes the most fundamental question of all, "what IS the nature of reality?"

I think it's important to go straight to the heart of the basics sometimes. To truely understand something one must know both what it does and what it IS. You can't claim to understand automobiles by simply saying, "well it's a vehical for carrying passengers from here to there." That's part of it, to be sure. But it only tells you what it does. You need knowledge and understanding of mechanics to know HOW it does it. You need knowledge and understanding of chemistry to know WHY it works. I see plenty of descriptions of the effect of space/time but very little discussion about WHAT it might be.

Would you consider that if it were possible (and I KNOW that it is not--I asking hypothetically) to create a box absolutely devoid of matter and energy that the space/time within that area would ALSO cease to exist; that you would truely have a box of "nothing"? I doubt it and it seems very counter-intutive to me. But I think it's worth considering. And, if you HAD a box of "nothing" would it then be possible to reach through one side and reach OUT the other without passing through the "in-between"? Agaiun, if there is turely "nothing" between here and there, you can move from point to point instantaneously, right?

Science often seems full of self-referential explanations that describe the EFFECT without eally defining the thing. Ex. Q. What is grass? Science: Well, it's green and grows in your yard. Uh, yeah, I SEE that. But what is it?

Clearly space/time exists. It has an observable effect. We effect it. It effects US. It is therefore a "Thing" (as opposed to being a "nothing"). Even if space/time and/or gravity is purely a phenomenon--an "effect" related to other causes, there is an OBJECTIVE motivator at the heart of it all. (Think of, say, wind, being an illusion. It is not a "thing" at all but the EFFECT of moving air masses--could gravity therefore be an "illusion" similar to the way wind might be described as such?)

Sometimes it's helful to take a step back and try a reductile approach. Ask the SIMPLEST questions possible and try to address the MOST fundamental aspects.

Ex. Is time travel possible?

Answer. ABSOLUTELY. We all do it every day. 1 second per second into the future. Therefore the question becomes NOT "Is time travel possible" as, CLEARLY it is, but rather, is it possible to control the direction and speed we travel through time?

It is NOT a semantical game though it may seem one. Rather, it is an attempt to look at things on their most fundamental levels.

 

[Shaw]

Wow... what a post.

I'll try to answer what I can, but limiting myself to English (which I'm not that good at) and not including math (which I'm better at) will make this rather challenging.

Stuff worth considering. It's frustrating sometimes when I see descriptions of the effect of something confused with the definition of the "something" itself. "It does this and we see that" etc. no, No NO! What IS IT? Not "what does it do"!...

Science often seems full of self-referential explanations that describe the EFFECT without eally defining the thing. Ex. Q. What is grass? Science: Well, it's green and grows in your yard. Uh, yeah, I SEE that. But what is it?

You are quite right, and science isn't the only school of thought that is guilty of it either. At the dawn of the 20th century mathematicians thought that they were on the verge of having the perfect logical structure... only to have Gödel show that the system was self-referencing.

And to a large degree isn't physics an attempt by the universe (of which we are part) to explain itself?

As for your box question, it makes for an interesting puzzle, but setting up such a puzzle so that it didn't violate the very system it is designed to test makes it difficult. And the study of where our understanding breaks down is of quite a lot of interest, which is called singularity theory.

For example, black holes start punching holes in the mathematics. In the last set of equations I originally posted, if the radius of the body of total mass M is less than or equal to 2M, the equations stop functioning the way one would expect. And that is why the event horizon is defined as the spherical boundary of radius 2M from a black hole.

Natural black holes form by collapsing on themselves, but that doesn't mean that a small mass M couldn't be crushed to a radius of less than 2M. It just wouldn't have the ability to sustain itself without external energy.

Clearly space/time exists. It has an observable effect. We effect it. It effects US. It is therefore a "Thing" (as opposed to being a "nothing"). Even if space/time and/or gravity is purely a phenomenon--an "effect" related to other causes, there is an OBJECTIVE motivator at the heart of it all. (Think of, say, wind, being an illusion. It is not a "thing" at all but the EFFECT of moving air masses--could gravity therefore be an "illusion" similar to the way wind might be described as such?)

Sure.

One of the most amazing things Einstein put forward in his arguments was some very straight forward mental experiments. For gravitation a room constantly accelerating actually covers much of the important aspects. A person inside the room can't tell if they are on the surface of a large body or in the middle of empty space in a state of constant acceleration. Even the bending of light can be produced in this experiment. By shooting a beam of light perpendicular to the rooms path from a stationary point, if the room is accelerating fast enough the light would enter the room on one side at a right angle, by the time it reached the other side it's angle would be off by a small amount (in the rooms frame of reference).

So in a real sense gravity could be thought of as similar a centrifugal force (in nature, not action). Centrifugal force is the opposite reaction to centripetal force. In the accelerating room there would have to be some force accelerating the room, so the room presents a force on objects within it the seems like gravity. So if gravity also seems like gravity, then the real force present would be the ground pushing back against us.

And in the same sense the weightlessness that astronauts feel is also an illusion as the gravitational effect of the Earth isn't really all that much less in orbit. The spacecraft are in a constant state of free fall, but are just missing the Earth. That free fall negates the effect of gravity in the same way that constant acceleration would create those same effects.

So the fact that reference frames exist that can either simulate or negate gravity does lean a strong argument to the idea that gravity as a force is an illusion. But that was what I was getting at earlier with the dual nature of gravity as both geometry and force, both perspectives are important.

Ex. Is time travel possible?

Answer. ABSOLUTELY. We all do it every day. 1 second per second into the future. Therefore the question becomes NOT "Is time travel possible" as, CLEARLY it is, but rather, is it possible to control the direction and speed we travel through time?

The funny thing about time travel is that there is a lot of stuff often overlooked.

Lets say we wanted to travel back to 6 months ago. If we were setting the Earth as our center of reference, then we might travel with it to where it was. But what if the Sun was the center of reference? Then we would pop up here but the Earth would be on the other side of the Sun from us (about 17 light minutes away).

Or what if we wanted to go back in time 40 years? And lets say that the center of the Milky Way was our reference point, then we would pop up here, but the Sun and Earth would be between 10 and 11 light days away. And that isn't even taking into account that the universe isn't the same either. The universe was a smaller place 40 years ago.



All these types of things are really fun to think about. It was questions just like yours that started me studying this area when I was a kid and those questions are not less interesting to me today than they were back then!

And sorry if any of that was unclear... I haven't had a lot of recent experience talking about this area in more general terms. I'm sure I missed some aspects that are important and I'm just not seeing them.

 

[Zachary Smith]

Thanks. Again, a lot to consider. I find the CONCEPTS of physics to be quite fascinating. I have, however NO ability at all to work with mathematical constructs.

Something as to the nature of time itself that I suspect is that, not only is the entire universe expanding, but EVERYTHING within it is expanding, albeit at at slightly varied rates. I think the greater MASS an object has, the slower it expands, which is why time would get effected in the vicinity of a massive object like a black-hole. It is expanding much SLOWER than the rest of the universe. We percieve the universe's expansion because the area between stars ("empty" space) is the least massive construct in the universe. It therefore expands the fastest.

And, yes, we too are expanding. We just don't notice it because everything in our immediate vicinity is expanding at a uniform rate. The effect becomes observable only on MASSIVE scales. Time, I suspect, is somehow a by-product of the expansion of space (which is why acceleration "slows" time for the observer--the "fabric of space becomes more dense in the path of the object accelerating) compressing both pace AND the object.

I think if it were possible to reach back with a time-travel device and snatch, say a person, from ten thousand years ago and move him to the present day, we might be surprised to find him physically SMALLER than we are--the ENTIRE universe was smaller back then--space and EVERYTHING it contained.

EDIT: Perhaps the reason singularities are infintesimally SMALL is because they are VERY slowly or NOT expanding AT all compared with the rest of the universe? In fact, what if, rather than blackholes COLLAPSING inward, it is instead that they all but CEASE expanding due to their density and it REST of the universe which expands much more rapidly around them, creating the ILLUSION they care collapsing inward?

 

[Jadzia]

Let's not fight. Zach has a good question, that is as much philosophy as it is science.

Thus, space/time is DEFINATELY a "something" as it effects (and actually DEFINES) our reality. Whatever space/time may be, it is not TANGIBLE to our senses; we see only the EFFECT it has upon us. But it is definately very real.

Ergo my question; what IS IT made of? Rather than looking for a metaphor that suffices merely to describe the effect of space/time, I'm wondering on a a FUNDAMENTAL level--what is it?

Well where do we start with this one Zach?

As I said in another post, what Berkeley taught us, we can only know our perceptions of reality, not reality itself. The substance of space-time is not apparent to our senses -- we have no sensory perceptions of it, so it only exists within our minds as an abstraction.

That doesn't answer your question though.

A similarly perplexing question is "what is energy made of?" or even "what is matter made of?" I happen to like that last one.

Whatever our answer we can keep asking the question, "but what is that made of?"

I personally resolve all of these paradoxes with idealism, the belief that there is no such thing as matter -- where all that exists is an interaction of thought forms. The more I explore this philosophy, the more inescapable it seems to me. So I believe that matter and time represent weaknesses in the relationships between thought forms.

 

[Zachary Smith]

Let's not fight. Zach has a good question, that is as much philosophy as it is science.

Thus, space/time is DEFINATELY a "something" as it effects (and actually DEFINES) our reality. Whatever space/time may be, it is not TANGIBLE to our senses; we see only the EFFECT it has upon us. But it is definately very real.

Ergo my question; what IS IT made of? Rather than looking for a metaphor that suffices merely to describe the effect of space/time, I'm wondering on a a FUNDAMENTAL level--what is it?

Well where do we start with this one Zach?

As I said in another post, what Berkeley taught us, we can only know our perceptions of reality, not reality itself. The substance of space-time is not apparent to our senses -- we have no sensory perceptions of it, so it only exists within our minds as an abstraction.

That doesn't answer your question though.

A similarly perplexing question is "what is energy made of?" or even "what is matter made of?" I happen to like that last one.

Whatever our answer we can keep asking the question, "but what is that made of?"

I personally resolve all of these paradoxes with idealism, the belief that there is no such thing as matter -- where all that exists is an interaction of thought forms. The more I explore this philosophy, the more inescapable it seems to me. So I believe that matter and time represent weaknesses in the relationships between thought forms.

Thanks Jadzia. I alays appreciate your input.


Where DO we start? Really that's my point in many ways; we haven't yet started AT ALL.

Some scientists would have us believe that we've got the bulk of the universe figured out. Many pontificate that this or that is "not possible", often with the caveat of "by the laws of physics as we understand them". But there seems always this undertone of, "and we've got it all pretty much figured out". Sure, they admit there's some i's to dot and some t's to cross, but the frame-work for the big-picture is pretty much in place.

I call "hubris" on this. There ARE answers, objective truths behind the concepts discussed here that are fact whether we understand them or not, whether we EXIST or not. The universe is FAR older than humanity and it hummed along fine without us for most of it's existance. These TRUTHS lay out there.

The fact that they ARE such intrinsic imponderables at this stage in our development demonstrates how LITTLE we really understand.

Ex. The often state phrase that energy can be neither created nor destroyed but can only change form.

HOW can something which CANNOT BE CREATED exist?

CLEARLY it exists. By our understanding of all things then, it MUST have been created somehow (and, NO, I am NOT going to argue for a god-like "creator-being"--I am an agnostic).

There is an imponderable at the heart of this matter--either something has ALWAYS existed, without ever having been created, or it did NOT exist and somehow WAS created.

It is NOT a philosophical question as there is an OBJECTIVE truth at the heart of the matter.

Either WE do not know how to create energy (and we'll NEVER learn to if we simply assume "it can't be done") or the reality we live in has purely natural elements that are completely beyond our reackoning and experience at this point. BASIC aspects, which we don't BEGIN to understand.

That's why I think questions like "What is space/time MADE from" are fundamental.

I've been scolded by "learned" science minds who have complained that the fact that I would ASK such a question betrays my ignorance of science. Conversely, I argue that NOT asking such questions HINDERS our understanding of the universe and betrays a hubris and over-confidence of ego that actually SLOWS our progress.

I am NOT a scientist. But I'm VERY interested in science. I appreciate the responses I've gotten here in this thread and at other times in this forum. I know it can be frustrating to have to explain something to take 5 paragraphs to explain something to me that another might be able to see in a single equation, but, like I said before, math is NOT my forte.

Ultimately though, I try to ask provacative questions in order to move things forward. Complaciency breeds entropy and I, personally, think we have FAR more to learn than we know, we have just BARELY scratched the surface and, perhaps, as we discussed in another thread, there may be aspects to the universe that we are simply INCAPABLE of understanding or learning due to the inherent limitations of our perceptions and ability to "know". That's not an arguement for giving up, however. Rather, it is an argument for trying HARDER.

 

[NCC621]

Wow... what a post.

I'll try to answer what I can, but limiting myself to English (which I'm not that good at) and not including math (which I'm better at) will make this rather challenging.

Okay, for whatever it's worth. I apologize for being snarky uptopic.

 

[Jadzia]

You're doing good Zach

HOW can something which CANNOT BE CREATED exist?

CLEARLY it exists. By our understanding of all things then, it MUST have been created somehow (and, NO, I am NOT going to argue for a god-like "creator-being"--I am an agnostic).

There is an imponderable at the heart of this matter--either something has ALWAYS existed, without ever having been created, or it did NOT exist and somehow WAS created.

Well science and philosophy won't be happy until they've gone right back to the beginning. What motivated the big bang, or what motivated creation?

Even if you start out with god -- god is something. What is god made from? We get back to square one, just with us looking at a grander universe.

The beginning of course, is nihility. (I tried to get a wikipedia link for you there, but it doesn't exist!! )

So anyway, how do we go from nihility to something? Nihility must be intrinsically unstable if has to change into something. Which if true, it means that it is impossible to create nihility. So you can't create your empty box.

 

[Paxil]

I just wonder if anybody else would know it if all those equations were total bullshit?

 

[Jadzia]

Well I know that level of math, and recognise the tensor thing. It looks like relativity, but I've never studies relativity so I don't know. But if nobody here understands them anyway, it doesn't matter if it is total bullshit.

Communication is a two person thing.

 

[Zachary Smith]

The equations could be chicken scratches in the earth for all I can tell of them.

 

[Daedalus12]

I just wonder if anybody else would know it if all those equations were total bullshit?

No they are not bullshit.

The problem with speculating about the natural of the universe is that it's constantly mind warping. I am beginning to think Plato was right. There are certain levels of the universe that the human brain cannot comprehend yet due to certain limitation in its structure.

 

[Zachary Smith]

Heh! Me and Plato . .. . we think a lot alike, don't we?

 

[Jadzia]

Plato was my hero.

.

 

[Zachary Smith]

Plato was my hero.

.

I liked his stories about Atlantis.

 

[Zachary Smith]

Question: You might consider it an exercise for you math-minded types.

Bearing in mind what was said in an earlier post about how micro gravity in orbit was really more of an illusion due to free fall and that the earth's pull was really little different even in orbit, if one were to somehow build a tower somewhere along the equator, a VERY tall tower with a room at the top, what altitude--if ANY--would there be a "zero-G effect" in the room? Also, would there ever be a point centrifugal force caused by the Earth's rotation would have you walking on the ceiling of that room instead of the floor?

 

[Daedalus12]

Question: You might consider it an exercise for you math-minded types.

Bearing in mind what was said in an earlier post about how micro gravity in orbit was really more of an illusion due to free fall and that the earth's pull was really little different even in orbit, if one were to somehow build a tower somewhere along the equator, a VERY tall tower with a room at the top, what altitude--if ANY--would there be a "zero-G effect" in the room? Also, would there ever be a point centrifugal force caused by the Earth's rotation would have you walking on the ceiling of that room instead of the floor?

The point of equilibrium is at the geostationary altitude. Below it you'll be on the floor and above it you'll be on the ceiling.

 

[Shaw]

Okay, for whatever it's worth. I apologize for being snarky uptopic.

Not a problem. How could I hold something like this against someone named after one of my favorite starships!

I just wonder if anybody else would know it if all those equations were total bullshit?

Actually I knew that both Verteron and Daedalus12 would be able to tell right off the bat. The only thing not stated is that I set the constants (c and G) in the general relativity equations to equal 1 so they wouldn't clutter up the basic form (seeing as the similarities between all of them was what I was attempting to show).

Besides, what would be the point in posting false or inaccurate information? Specially if that information could easily be checked? To assume that I was BSing would imply that I thought what I wrote was uncheckable by pretty much everyone on the net, or that no one here would know the difference. I don't think I was showing that type of disrespect in that post, so it seems like that would rule out that type of motivation.

Question: You might consider it an exercise for you math-minded types.

Bearing in mind what was said in an earlier post about how micro gravity in orbit was really more of an illusion due to free fall and that the earth's pull was really little different even in orbit, if one were to somehow build a tower somewhere along the equator, a VERY tall tower with a room at the top, what altitude--if ANY--would there be a "zero-G effect" in the room? Also, would there ever be a point centrifugal force caused by the Earth's rotation would have you walking on the ceiling of that room instead of the floor?

Actually Clark brought up towers like that in his book 3001. They would be built along the equator and the top floor was at the geosynchronous orbit (about 22,233 miles up). Any floors above that would have a reversal of orientation (looking up at the Earth)

Edit: Daedalus12 beat me to it.

 

[Paxil]

Relax, I'm not accusing you of anything, it was more of a compliment really. I considered myself a very smart person until I started seeing some of the things being posted here.