Question pertaining measurement and space

  • Thread starter Thread starter BigM69
  • Start date Start date
  • Tags Tags
    Measurement Space
BigM69
Messages
1
Reaction score
0
if there is an infinite amount of distance between two points in space because you can break that distance up into an infinite amount of different points then how can one move through space at all?
 
Physics news on Phys.org
If we take two points a finite distance apart, there may be an infinite number of points between them, but the distance between them is still finite.

The detailed math on this gets into what's known as "measure theory". I'm not sure if you REALLY want a detailed mathematical answer, but if you do, you might try the math forums. About all I can remember about the topic is that if the measure of an infinite set of points such as the interval [0,1] is finite, the measure of ANY finite set of points turns out to be zero. I don't recall the axioms that were used to prove this offhand, though.
 
Another way of addressing Zeno's paradox is to note the fact that in calculus, an infinite series of numbers can have a finite sum--for example, the sum of the infinite series 1 + 1/2 + 1/4 + 1/8 + 1/16 + ... is just 2. So if you want to travel one meter at a speed of half a meter per second, it'll take 1 second to cross the first half-meter, 1/2 a second to cross the next fourth of a meter, 1/4 a second to cross the next eight of a meter, and so on...so although you can break up the total time into an infinite number of time-intervals, the total time is still just 2 seconds.
 
OK, so this has bugged me for a while about the equivalence principle and the black hole information paradox. If black holes "evaporate" via Hawking radiation, then they cannot exist forever. So, from my external perspective, watching the person fall in, they slow down, freeze, and redshift to "nothing," but never cross the event horizon. Does the equivalence principle say my perspective is valid? If it does, is it possible that that person really never crossed the event horizon? The...
ASSUMPTIONS 1. Two identical clocks A and B in the same inertial frame are stationary relative to each other a fixed distance L apart. Time passes at the same rate for both. 2. Both clocks are able to send/receive light signals and to write/read the send/receive times into signals. 3. The speed of light is anisotropic. METHOD 1. At time t[A1] and time t[B1], clock A sends a light signal to clock B. The clock B time is unknown to A. 2. Clock B receives the signal from A at time t[B2] and...
From $$0 = \delta(g^{\alpha\mu}g_{\mu\nu}) = g^{\alpha\mu} \delta g_{\mu\nu} + g_{\mu\nu} \delta g^{\alpha\mu}$$ we have $$g^{\alpha\mu} \delta g_{\mu\nu} = -g_{\mu\nu} \delta g^{\alpha\mu} \,\, . $$ Multiply both sides by ##g_{\alpha\beta}## to get $$\delta g_{\beta\nu} = -g_{\alpha\beta} g_{\mu\nu} \delta g^{\alpha\mu} \qquad(*)$$ (This is Dirac's eq. (26.9) in "GTR".) On the other hand, the variation ##\delta g^{\alpha\mu} = \bar{g}^{\alpha\mu} - g^{\alpha\mu}## should be a tensor...
Back
Top