I have been going on about space time for ages now and yet I have failed to ask what the current thinking is.

What is the current thinking as to what space time actually is?

Does some one have a useful link that explores what space time is?
I have always thought of space time and gravity as being the same thing.

As James R says, one way of looking at it is as a coordinate system!

It's sort of funny you know, with the limited research I have done every theory has come done to some sort of particle.

Is it possible that things can exist that aren't particles of some sort.

Like an a sheet of glass for example, whilst we know that it consists of particles could not space simply be like a "particle less" sheet of glass?

Why do we tend towards this concept of particle?

BTW I think "a point co-ordinate system" is a good part of the description.

Einstein's approach that volume was dependent upon entropy and Boltzmann's approach that entropy was dependent upon volume suggests the only way to define space is by its entropy. Otherwise one accepts the concept of space as a void, as nothingness, unaffected by energy. If space is defined by the parameters of the containment of energy as is further suggested in Stochastic Electrodynamics than time may be related to entropy through a vehicle such as the Rindler Flux. Space cannot be quantized through a grid of units of space because there is nothing to prevent the energy in the grid from going to infinity - ie., the singularity of a black hole. If the volume of the black hole increases as energy is deposited into the black hole from space this suggests that the expansion or contraction of volume based upon energy can be quantized by time. Minkowski stated that relativity eliminated the distinction between time and space creating what he termed spacetime. If Time = sqrt 2 * 2pir/c as related hereafter and sqrt (e/m) = c, as mass increases, energy must increase, otherwise the speed of light would not be a constant. If kept constant then for time to be positive the radius must be positive and have a direction. If Boltzmann was correct that entropy was dependent upon volume than such suggests that mass falling into a blackhole would not cause the volume of the black hole to expand. In fact if entropy were dependent upon volume there could be no change to the area of the event horizon of a black hole by the introduction of mass. A Boltzmann black hole would repell or destroy mass because an increase in entropy would not affect the event horizon. But a Boltzmann black hole violates the second law of thermodynamics - entropy always increases or stays the same and never decreases. For both Boltzmann and Einstein to be consistent something must exist which measures the direction and area of the event horizon, in this case time. Thus, time can be utilized to explain how space is stretched.

More at:

http://clickit.go2net.com/search?pos=48&ppos=6&plnks=0&uplnks=20&cat=web&cid=239156&site=srch&area=srch.noncomm.about&shape=textlink&cp=info.dogpl&cluster-click=0&pd=0&coll=1&query=space+time&rawto=http://clk.about.com/?zi=3/ck/1B&zu=http://physics.about.com/cs/alternativeideas/a/unification_rk.htm

"with out time space is nothing" comes to mind......

Cosmictraveler,

Otherwise one accepts the concept of space as a void, as nothingness, unaffected by energy. If space is defined by the parameters of the containment of energy as is further suggested in Stochastic Electrodynamics than time may be related to entropy ...

I could certainly agree with this. :D

"with out time space is nothing" comes to mind......


I could agree with this too. :D

"with out time space is nothing" comes to mind......

Thats like saying without length, width is nothing.

To my way of thinking space consists of at least two dimensions, Distance ( width, length and depth) and time. Or maybe to simplify, volume and time.
But with out time volume has no meaning other than a mental abstraction.

To travel the distance must take time so volume is only of any relevance if time is needed to travel within that volume.

so distance implies time. If no time needed then no distance is present.

so without time, space is nothing seems to make sense...to me anyway..

What is the current thinking as to what space time actually is?

If we're speaking about relativity, as opposed to quantum gravity (for which there is no complete theory) then spacetime is a collection of events where an event consists of a place and a time.

The relationship between events may change in the presence of a gravitational field.

Anything more than that I don't think is measurable.

Pete

I think that the best answer anyone has to this question probably occurs in the field of quantum electrodynamics. I think that at one time, it was believed, based on a theory by P.A.M. Dirac, that space was filled with a reservoir of unobservable negative energy particles, or some such thing. Probably one would have to read quantum and QED books to see what the current best answer is. I don't think that geometric theories like General Relativity will ultimately provide much of an answer.

The idea of spacetime, though, arose in Special Relativity, out of the fact that the coordinates (x,y,z,t) or actually (x,y,z,ict) were handled together in the equations, making the term spacetime more relevant than the separate concepts of space and time. I think that in the years that followed Einstein's 1905 paper, Minkowski had something to do with deciding how coordinates should be handles in Special Relativistic calculations.

Why do we tend towards this concept of particle?

What is YOUR deBroglie Wavelength (http://hyperphysics.phy-astr.gsu.edu/hbase/debrog.html#c5)?

("h" in the formula is Plank's Constant)

Could space/time be defined as something that provides the medium for the potential existence of particles & energy? Dark energy could be a quality of this medium where the medium is constantly replicating itself, causing the expansion of the universe.