What is space? - Tilted Forum Project Discussion Community

09-22-2004, 05:39 AM

OK, strange start to a post, and please excuse my roundabout style - either way, I'm interested in in your ideas...

Speed is a function of how far you can travel within a certain time. Apparently there is a limit on how fast you can go, but this post isn't about that (directly). The question is; What exactly is distance anyway?

Assume you are in space and you want to measure the distance between yourself and another object. How would you do it? Perhaps by shining a light at it and seeing how long it took for the light to be reflected back? Divide by speed of light and there's your distance. So distance in fact, can most simply be considered as a function of time. i.e. The length of time it takes for one object to effect or signal with another. It also suggests that distance as a concept is meaningless without matter.

So what is the 'stuff' made of that separates objects? Some people call it space-time and describe it bending in response to masses operating within it (i.e. gravity), others describe warping it to achieve faster-than-light travel, or spinning it to create time-machines - the rest of us just live in it - but what actually is it?

What if space-time was made of the same stuff as matter and energy? Matter and energy have been found to be equivalent i.e. convertable according to e = mc^2 and it always puzzled me as to why the c should be found in the equation. c describes the speed of light, or the distance traveled (space) within a set period (time) which means that spacetime is also represented in the equation.

If it's possible to use it to prove the equivalence of matter and energy, is it not also possible to show the equivalence of time, space, matter and energy too? What might that mean? I don't really know...I just thought it would be an interesting question...

the_marq · 09-22-2004, 06:12 AM

OK I am not a physics major but I did recently read some really good articles about Einstein. So as a layman I understand it as this (and please feel free to correct me if there are any physics majors out there):

Matter and engery are not equivelent, that's the whole point of e=mc^2. IE: a small amount of matter is equal to a massive amount of energy.

Perceptions of space and time have been debated for quite some time and again as I understand it, they are essentially different versions of the same thing. That is to say: both space and time are simply ways to describe the location of a 'thing.'

For example: I exist at X,Y,Z coordinates (space) at this point in time.

09-22-2004, 06:22 AM

By equivalence, I mean that matter can be turned into energy (according to the equation) Like converting US Dollars into Hungarian Forints, one may be worth a lot more than the other, but they are both equivalent in that they can be used to buy stuff and can be freely converted back and forth (less commision of course)

The idea that space is not just a location is also what I'm trying to get at - because for space to have ANY meaning, it must contain matter or energy (because the only way to define space-time is in terms of matter or energy - e.g. in your xyz-t example, how do you define point 000-0?).

Perhaps it is no coincidence, and that space, time, matter and energy are all different variations of the same thing. That they are all different manifestations of the fabric of the universe - whatever that is.

Phage · 09-22-2004, 01:14 PM

Quote:

Originally Posted by zen_tom

Assume you are in space and you want to measure the distance between yourself and another object. How would you do it? Perhaps by shining a light at it and seeing how long it took for the light to be reflected back? Divide by speed of light and there's your distance. So distance in fact, can most simply be considered as a function of time. i.e. The length of time it takes for one object to effect or signal with another. It also suggests that distance as a concept is meaningless without matter.

Space is meaningless without a point of reference, which I suppose would be a chunk of matter. However, I don't think that matter is required. If you can imagine firing light off from an empty point and seeing when it passes another, you should be able to measure space.

09-23-2004, 03:22 AM

Unfortunately you can't see light passing a point, it needs to be reflected to be seen (seeing it is actually a process of turning the light hitting a cell in your eye into an electrical signal)- and to have something to do that reflecting requires some form of matter.

And since light is energy (which is equivalent to matter anyway) as soon as you fire it off, it is a THING occupying, and travelling (perhaps even creating) space.

Yes, space is meaningless without a point of reference (or matter) in it, but further; perhaps matter is meaningless without space. The point I'm trying to make is that the two previously separate ideas we have about space-time and the things that inhabit it are perhaps more intertwined than we think - and are perhaps the manifestations of a deeper something.

09-22-2004, 05:39 AM	#1 (permalink)
zen_tom Guest	What is space? OK, strange start to a post, and please excuse my roundabout style - either way, I'm interested in in your ideas... Speed is a function of how far you can travel within a certain time. Apparently there is a limit on how fast you can go, but this post isn't about that (directly). The question is; What exactly is distance anyway? Assume you are in space and you want to measure the distance between yourself and another object. How would you do it? Perhaps by shining a light at it and seeing how long it took for the light to be reflected back? Divide by speed of light and there's your distance. So distance in fact, can most simply be considered as a function of time. i.e. The length of time it takes for one object to effect or signal with another. It also suggests that distance as a concept is meaningless without matter. So what is the 'stuff' made of that separates objects? Some people call it space-time and describe it bending in response to masses operating within it (i.e. gravity), others describe warping it to achieve faster-than-light travel, or spinning it to create time-machines - the rest of us just live in it - but what actually is it? What if space-time was made of the same stuff as matter and energy? Matter and energy have been found to be equivalent i.e. convertable according to e = mc^2 and it always puzzled me as to why the c should be found in the equation. c describes the speed of light, or the distance traveled (space) within a set period (time) which means that spacetime is also represented in the equation. If it's possible to use it to prove the equivalence of matter and energy, is it not also possible to show the equivalence of time, space, matter and energy too? What might that mean? I don't really know...I just thought it would be an interesting question...

09-22-2004, 06:12 AM	#2 (permalink)
the_marq All hail the Mountain King Location: Black Mesa	OK I am not a physics major but I did recently read some really good articles about Einstein. So as a layman I understand it as this (and please feel free to correct me if there are any physics majors out there): Matter and engery are not equivelent, that's the whole point of e=mc^2. IE: a small amount of matter is equal to a massive amount of energy. Perceptions of space and time have been debated for quite some time and again as I understand it, they are essentially different versions of the same thing. That is to say: both space and time are simply ways to describe the location of a 'thing.' For example: I exist at X,Y,Z coordinates (space) at this point in time. __________________ The Truth: Johnny Cash could have kicked Bruce Lee's ass if he wanted to. #3 in a series

09-22-2004, 06:22 AM	#3 (permalink)
zen_tom Guest	By equivalence, I mean that matter can be turned into energy (according to the equation) Like converting US Dollars into Hungarian Forints, one may be worth a lot more than the other, but they are both equivalent in that they can be used to buy stuff and can be freely converted back and forth (less commision of course) The idea that space is not just a location is also what I'm trying to get at - because for space to have ANY meaning, it must contain matter or energy (because the only way to define space-time is in terms of matter or energy - e.g. in your xyz-t example, how do you define point 000-0?). Perhaps it is no coincidence, and that space, time, matter and energy are all different variations of the same thing. That they are all different manifestations of the fabric of the universe - whatever that is.

09-23-2004, 03:22 AM	#5 (permalink)
zen_tom Guest	Unfortunately you can't see light passing a point, it needs to be reflected to be seen (seeing it is actually a process of turning the light hitting a cell in your eye into an electrical signal)- and to have something to do that reflecting requires some form of matter. And since light is energy (which is equivalent to matter anyway) as soon as you fire it off, it is a THING occupying, and travelling (perhaps even creating) space. Yes, space is meaningless without a point of reference (or matter) in it, but further; perhaps matter is meaningless without space. The point I'm trying to make is that the two previously separate ideas we have about space-time and the things that inhabit it are perhaps more intertwined than we think - and are perhaps the manifestations of a deeper something.