Talk: Spacetime

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Summaries of earlier Talk (see [1])

Space-time vs. Spacetime

Examples of use of spacetime:

• Weisstein's encyclopedia http://www.treasure-troves.com/physics/
• D. J. Griffiths' Introduction to Electrodynamics (Upper Saddle River, N. J.: Prentice-Hall, 1989)
• numerous books with spacetime in title
  • E. F. Taylor and J. A. Wheeler, Spacetime Physics (San Francisco: W. H. Freeman, 1966)
• Caltech class: "Spacetime 101"
• .edu matches online are almost exclusively for spacetime

Examples of use of space-time:

• Brehm & Mullin, Introduction to the Structure of Matter (ISBN: 047160531X)
• Merriam-Webster http://www.m-w.com
• space-time about four times as many hits as spacetime on AltaVista

Since Wikipedia is not a dictionary, it should stick to one spelling. Thus I removed the comment "(alternatively, space-time)". Space-time already redirects to Spacetime, so all is well. —Herbee 20:31, 11 Nov 2004 (UTC)

The Spacetime four vector

The space-time four vector is:

[x y z ct]

the use of the vector as:

[x y z ict]

was common about 40 years ago or so, but it is now considered archaic and the former notation is prefered.--BlackGriffen

However, there are certainly physicists who prefer the i notation, including Dr. Jack Sarfatti.

The Wikipedia should present the mainstream state of a field as much as possible, presenting relevant dissenting views as such when they arise. The use of the i is just a lazy way to make finding the "length" squared of a four vector feel like finding the length of any other vector (dot product the vector on to itself). It is, however, just as easy to define a new "length" operator for four vectors that doesn't require complex numbers.

And if bandying about names is the game, a quick look at the Feynmann Lectures on Physics explanation of four vectors shows nary an i, even though he had a discussion of using c=1.--BlackGriffen

I concur: both 'space-time' and the 'i' notation appear to be common early usage, and physicists everywhere seem now to have standardised on both 'spacetime' and the 'i'-less notation -- The Anome

1: Is there a free 3d prog that does nice, uniform renderings of some of this math?

2: Might it be a good idea to use a sidebar (can even use a msg tag for multiple article consistency) which describes some of the core foundational concepts, required for laymen learners like myself to have related study materiale at hand. Finding links in the text lacks structure that a weeded list would have. -SV(talk)

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New Talk

We can read in this article:

"Strictly speaking one can also consider events in Newtonian physics as a single spacetime. This is Galilean-Newtonian relativity, and the coordinate systems are related by Galilean transformations. However, since these preserve spatial and temporal distances independently, such a spacetime can be decomposed unarbitrarily, which is not possible in the general case." - is that right? Is unarbitrarily or arbitrarily? I've some difficulties with english but I'm trying to translate this to portuguese and I can't understand this... Is it an error?... Say something, please. -- Manuel Anastácio 20:29, 15 Jun 2004 (UTC)