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Is this a typo, or just a misunderstanding on my part? These two quotes seem to be diametrically opposed in their explanation of Special Relativity in two parts

Is this a typo, or just a misunderstanding on my part? These two quotes seem to be diametrically opposed in their explanation of Special Relativity in two parts of the article. > When you go fast, he said, the world around you changes shape, and time outside starts moving slower. > Since the boats are going fast, the space doctor’s special idea says that their watches will run a little slower than the ones on Earth. Shouldn't time outside start moving faster in the first quote?

Strilanc 11y ago
It's not a typo. When two ships are moving fast relative to each other, they both determine the other's clocks to be ticking slower. http://casa.colorado.edu/~ajsh/sr/paradox.html http://casa.colorado.edu/~ajsh/sr/paradox.html
phasmantistes 11y ago
That's the beauty of relativity, and why it is called relativity: it's all relative. When you go fast, and look outside, it looks like it is the outside that is moving fast (unless you are experiencing acceleration, at which point General Relativity kicks in). Therefore, to you, it looks like time outside is moving slower. When the space boats are doing their thing, to us on the outside it looks like they are moving fast. Therefore, to us, it looks like time for them is moving slower.
AnimalMuppet 11y ago
Yes. No. Maybe? If I'm moving very fast with respect to you, I see your watch running slow, and you see my watch running slow. So the first paragraph is true, if it's talking about your view - the world around you changes shape, and time outside moves slower, as seen by you. The second paragraph is true, as seen from Earth, not from the boats.
ultrafilter 11y ago
I think your watch is slow and you think mine is slow in the following sense. For each of many events, I record their time t and position x while you, moving relative to me at constant velocity, observe a different time T and position X. Between two events with the same X-value, such as ticks of your pocket watch, the difference in t-times is larger than the difference in T-times by a factor gamma. Conversely, between two events with the same x-position, such as ticks of my pocket watch, the difference in T-times is larger than the difference in t-times by that same factor gamma. There is no contradiction because events with identical x-positions do not have identical X-positions. If you already know what a partial derivative is, see the first paragraph of this: http://mathpages.com/rr/s4-07/4-07.htm http://mathpages.com/rr/s4-07/4-07.htm

Strilanc 11y ago

It's not a typo. When two ships are moving fast relative to each other, they both determine the other's clocks to be ticking slower. http://casa.colorado.edu/~ajsh/sr/paradox.html http://casa.colorado.edu/~ajsh/sr/paradox.html

phasmantistes 11y ago

That's the beauty of relativity, and why it is called relativity: it's all relative. When you go fast, and look outside, it looks like it is the outside that is moving fast (unless you are experiencing acceleration, at which point General Relativity kicks in). Therefore, to you, it looks like time outside is moving slower. When the space boats are doing their thing, to us on the outside it looks like they are moving fast. Therefore, to us, it looks like time for them is moving slower.

AnimalMuppet 11y ago

Yes. No. Maybe? If I'm moving very fast with respect to you, I see your watch running slow, and you see my watch running slow. So the first paragraph is true, if it's talking about your view - the world around you changes shape, and time outside moves slower, as seen by you. The second paragraph is true, as seen from Earth, not from the boats.

ultrafilter 11y ago

I think your watch is slow and you think mine is slow in the following sense. For each of many events, I record their time t and position x while you, moving relative to me at constant velocity, observe a different time T and position X. Between two events with the same X-value, such as ticks of your pocket watch, the difference in t-times is larger than the difference in T-times by a factor gamma. Conversely, between two events with the same x-position, such as ticks of my pocket watch, the difference in T-times is larger than the difference in t-times by that same factor gamma. There is no contradiction because events with identical x-positions do not have identical X-positions. If you already know what a partial derivative is, see the first paragraph of this: http://mathpages.com/rr/s4-07/4-07.htm http://mathpages.com/rr/s4-07/4-07.htm