How come we say space and time when it should be space=time. You can

[binbots]

How come we say space and time when it should be space=time. You can eliminate measuring distances and measure them in time. Two objects can always be measured apart by time as long as there is a universal speed (light). I am 0.000008sec (at light speed) from my mailbox for example. The universe expanding could be time. There is no distance at all. Like the big bang all matter is one thing only separated by time. The closer to people come together the closer in time they are. Have I gone to far with relative time?

 

[atyy]

Yes, space=time in terms of units of measurement. Properly, we say spacetime to indicate that it is a 4 dimensional entity, needing 4 coordinates to specify the location of one point of it. For convenience, we often work with one coordinate system, in which case we arbitrarily choose one way of dividing spacetime into space and time, in which case we say space and time.

 

[Dale]

How come we say space and time when it should be space=time.

This is not quite correct. Even in units where c=1 space does not equal time as you can easily see from the Minkowski metric:
$$ds^2=dt^2-dx^2-dy^2-dz^2$$

They are certainly related, but not the same.

 

[Passionflower]

This is not quite correct. Even in units where c=1 space does not equal time as you can easily see from the Minkowski metric:
$$ds^2=dt^2-dx^2-dy^2-dz^2$$

Well actually ds is time in this equation, dt is coordinate time, which only equals proper time in the special case where dx, dy and dz are all 0.

 

[Dale]

Well actually ds is time in this equation

Only for timelike intervals, not spacelike or null intervals. In which case time and space still differ in the sign of the interval squared.

 

[binbots]

So it is crazy to say that there is no such thing as space or distance. Only time separates all mass.

 

[nismaratwork]

So it is crazy to say that there is no such thing as space or distance. Only time separates all mass.

No, there can be space-like separations too... unless you mean within a specific coordinate system where time acts for distance.

 

[valavel]

So it is crazy to say that there is no such thing as space or distance. Only time separates all mass.

I will not attempt to answer this question, rather ask a related one: Is this the right thread to discuss the possibility of an Lorentzian relativity where it is not space and time that vary but the dimensions of moving masses that contract, and the rate of the clock mechanism that slows down - in a classical world? Other theories propose that space and time do not exist as separate dimensions and that c varies according to the density of the gravitational potential.

 

[nismaratwork]

I will not attempt to answer this question, rather ask a related one: Is this the right thread to discuss the possibility of an Lorentzian relativity where it is not space and time that vary but the dimensions of moving masses that contract, and the rate of the clock mechanism that slows down - in a classical world? Other theories propose that space and time do not exist as separate dimensions and that c varies according to the density of the gravitational potential.

There are such theories, are you promoting them?

 

[binbots]

What I am trying to say that distance is a man made thing. There is no universal measurment for distance. Time on the other hand has light, the universal constant.

 

[Mentz114]

What I am trying to say that distance is a man made thing. There is no universal measurment for distance. Time on the other hand has light, the universal constant.

You will probably find it ironic then that the standard metre is defined in multiples of the wavelength of certain light emissions. See here

http://en.wikipedia.org/wiki/Metre#Standard_wavelength_of_krypton-86_emission

 

[bapowell]

What I am trying to say that distance is a man made thing. There is no universal measurment for distance. Time on the other hand has light, the universal constant.

Why does time have light while distance does not have light?

 

[valavel]

There are such theories, are you promoting them?

The premises I mentioned seem very reasonable and I would like to know if others have worked out their full implications - i.e. can they rigorously lead to Einstein's results? In chapter VI of his book Space, Time & Gravitation, Eddington likens a gravitational field to a dense medium with a refractive index n where light slows down. He explains it is the 'coordinate' velocity of light he is talking about... but is this the right forum to discuss these things? Thanks.