| From: Birela | 30/11/2000
12:07:35 |
| Subject: Time, what is it? | post id:
178872 |
| I always thought that time was
the fourth dimension. But is it something created as a consequence of
mass, like gravity? If time isn't a dimension what is? I've heard of space time so does space have qualities like gravity fields and time fields? Or should I just stick to painting and leave thinking to scientists? | |
| From: Chris (Avatar) | 30/11/2000
12:39:31 |
| Subject: re: Time, what is it? | post id:
178907 |
Hi Birela I always thought that time was the fourth dimension. If time isn't a dimension what is? In relativity time is a fourth dimension. Way back around 1908 or so (a few years after Einstein published his special theory of relativity) a guy called Hermann Minkowski said "Henceforth absolute space and time shall cease to exist as separate concepts" (or words to that effect). What Minkowski had just done was to unify 3 dimensional space and one dimensional time into a single four dimensional manifold. Travel through space and time are interlinked, and we can see how by considering the Minkowski invariant interval: I2 = ct2 - x2 -y2 - z2 Don't let the math scare you - this is just pythogoras' relation: a2 = b2 + c2 except instead of b and c we have three space dimensions: x, y, z and one time dimension: -ct (the c is the speed of light). When we work out problems in special relativity we use this flat "Minkowski space" with three space dimensions and one time dimension. When we work out problems in general relativity we use a similar 4D space with three space dimensions and one time dimension - except that general relativity is a theory including gravity, so the dimensions can "bend" and thus the 4D space is not flat (it curves). You may see other discussions of higher dimensional spaces in quantum physics: eg Kaluza-Klein theory has 11 spatial dimensions; versions of string theory may have up to 26 spatial dimensions. These are largely mathematical tools to help us understand how symmetries in quantum physics can be broken and then restored. Probably best to stick to the 3D space + 1D time of relativity. But is [time] something created as a consequence of mass, like gravity? No. Time is not a consequence of mass. You could have a universe with time but no mass. However gravity does affect time. I've heard of space time so does space have qualities like gravity fields and time fields? In general relativity space-time is the gravity field (in a sense). Mass-energy bends or warps space-time, and then warped space-time tells mass-energy how to move. This is the action of gravity. Or should I just stick to painting and leave thinking to scientists? Ugh! Don't do that! :o) (asking intelligent questions is an indication of thinking, not an indication of stupidity). Hope this helps! Chris | |
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