Space in place.

[GutZ]

I am rhyming to make my case!

 

Ok i'll stop that.

 

I was under the impression before that space inherently grid or point like. I am starting to get from what I read here that this is not true. Is because space has no specific point of reference? Like is space just...space where things happen? Lets say you had nothing but space...could you pick a specific point and that point have any relevance to another point?

 

How is that possible if matter can interact with it? Is interact a bad word to describe the relationship?

 

I get that there are mathematical models of space, are they more representations of how space behaves rather than an exact description of space? What seperate space from no space?

 

lol what exactly do we know about?

[ydoaPs]

Distance is merely the separation of objects and the magnitude of which is determined by the energy density in the chosen frame of reference.

[GutZ]

"Distance is merely the separation of objects and the magnitude of which is determined by the energy density in the chosen frame of reference."

 

Could you expand a little on that part..I am still confused over frames of reference.

 

Is it just a point to which you measure from?

[ydoaPs]

Could you expand a litte on that part..I am still confused over frames of reference.

 

Is it just a point to which you measure from?

 

Imagine a universe in which all that exists are three balls(one red, one blue, and one yellow). Each ball has a mass of 1kg. The red and blue balls are at rest with respect to each other, but are moving with respect to the yellow ball. From a reference frame in which the yellow ball is at rest, the red ball and the blue ball are moving and thus have kinetic energy. Now, let's move our reference frame to one in which the blue ball is at rest. The red ball at rest relative to the blue ball, so has no kinetic energy(and neither does the blue ball). The yellow ball, however, is moving and thus has kinetic energy. The red ball has more energy in the reference frame of the yellow ball than it does in the reference frame of the blue ball. Thus energy is dependent on the reference frame and is not conserved from frame to frame. Mass, however is the same in every frame of reference. If we consider the three balls as a system and use the same reference frames, we get different values for the total energy of the system.

 

As stated, each ball has a mass of 1kg. In the reference frame where the red and blue balls are at rest, the yellow ball is observed to be moving at 100m/s with respect to the red and blue balls. In the reference frame where the yellow ball is at rest, the red and blue balls are each observed to be traveling at 100m/s with respect to the yellow ball.

 

How much KE does this universe have?

 

While energy is conserved in a frame of reference, it is not invariant between reference frames.

[GutZ]

I get it. that makes a lot more sense.

 

Thanks.

 

So does that mean you can't predict anything about an object (speed and energy) without a specified frame of reference?

[ydoaPs]

I get it. that makes a lot more sense.

 

Thanks.

 

So does that mean you can't predict anything about an object (speed and energy) without a specified frame of reference?

 

Speed is meaningless without a reference. As swansont once said, asking the speed of an object without specifying a reference is like asking the difference between a duck.

[Severian]

Let me reprocued my view from another thread:

 

In my opinion, we should simply regard space and time as a "rule" for determining a "distance" between two events. So all events have a particular property with respect to any other event called "distance" and how these distances are related is give by the "rule" of space-time (e.g. a Minkowski metric). The bending of space-time is then simply an alteration of this rule.

 

So, in the context of this thread, you notice that the 'rule' for distance I mention needs to have two events. With one event (or object) there is nothing to compare to so no concept of distance.

[GutZ]

What is the difference between a field and space? Or do you actually have to create a field? Like a Electromagnetic field How does is relate in space or...lack of a better word; fit in space?

 

Or is it all just more of mathematical model as in it follows nature to a tee, but the physical properties are not really physical in that sense.

[ydoaPs]

What is the difference between a field and space? Or do you actually have to create a field? Like a Electromagnetic field How does is relate in space or...lack of a better word; fit in space?

 

Or is it all just more of mathematical model as in it follows nature to a tee, but the physical properties are not really physical in that sense.

 

A field is a region of space that has a value at every point. There are vector fields(every point has a magnitude and direction, like electric fields) and scalar fields(every point only has a magnitude, like temperature fields).

[GutZ]

Yeah I gather that part, but are they actually points in space? I've been told this was an incorrect description of what space is like.

 

Say an electron is flying through space...Is it charged by the field? or are particles either inherently charged a specific way?

[ydoaPs]

Yeah I gather that part, but are they actually points in space? I've been told this was an incorrect description of what space is like.

 

Say an electron is flying through space...Is it charged by the field? or are particles either inherently charged a specific way?

 

The charge is what makes the field. Just look at the Maxwell equations. The field is just a representation of the electrical potential at each point. It can be represented as a vector field or a scalar field. You can think of the field as taking up the entire space and the values changing with respect to time. It's just that remote parts of the space are zero or near zero.

[GutZ]

Awesome! thanks that solves it for me.