tag:blogger.com,1999:blog-3891434218564545511.post1370986555178348929..comments2024-03-28T13:23:50.623-05:00Comments on Alexander Pruss's Blog: Time and clocksAlexander R Prusshttp://www.blogger.com/profile/05989277655934827117noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-3891434218564545511.post-16269493216047522892018-07-21T11:57:37.999-05:002018-07-21T11:57:37.999-05:00To be precise: The fact x occupies space means tim...To be precise: The fact x occupies space means time passes for x.Philip Randhttps://www.blogger.com/profile/09143527524267821692noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-62646120054973129562018-07-21T11:00:50.098-05:002018-07-21T11:00:50.098-05:00It would not be fair if I did not give you the sol...It would not be fair if I did not give you the solution... so, here it is:<br /><br />Your thought experiment is this:<br />"Consider an object x that travels over some path P in spacetime. How long did the travels of x take? Well, if in fact x had a clock traveling with it, we can say that the travels of x took the amount of time indicated on the clock.<br /><br />But what if x had no clock with it? Surely, time still passed for x."<br /><br />ANSWER: Since there is no difference between space and time it means that for particle x; p(t)=1/[c(t2-t1)]. This states that the probability of detecting x is the same at all times, and varies inversely with the total detection time. If the constant p(t) is small, then there is a constant tendency toward annihilation of x, etc. for the other extreme. The fact that x exists means that time passed for x.<br />Philip Randhttps://www.blogger.com/profile/09143527524267821692noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-63227867133224513902018-07-21T10:30:06.249-05:002018-07-21T10:30:06.249-05:00Einstein said that time is what clocks measure.
E...Einstein said that time is what clocks measure.<br /><br />Einstein means that there is no distinction between space and time.<br /><br />This solves your spacetime puzzles.Philip Randhttps://www.blogger.com/profile/09143527524267821692noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-75775814645985515562018-05-02T14:25:26.336-05:002018-05-02T14:25:26.336-05:00The photon bouncing back and forth requires a phot...The photon bouncing back and forth requires a photon and two walls.<br />The method described in the post requires a particle and a laser and other measuring apparatus.<br />There is also a historical question: Did Einstein think that every physical system had a periodic event?Alexander R Prusshttps://www.blogger.com/profile/05989277655934827117noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-11231134129593560202018-05-02T13:55:11.315-05:002018-05-02T13:55:11.315-05:00I do not think Einstein had common clocks (with ha...I do not think Einstein had common clocks (with hands and so forth) in mind when he defined time as that which clocks measure. Such an interpretation strikes me as quite uncharitable. Here a clock is any physical system in which certain event occurs periodically. For example, a photon bouncing between two static walls. Every "bounce" marks a "tick". Since we know that the photon's speed is constant, and that the distance traveled by it remains always the same, it follows that the time between two "bounces" is also always the same, so they satisfy the periodicity condition. Ok, all particles are clocks in this generalized sense which presumably Einstein had in mind. I really recommend the following post by German theoretical physicist Sabine Hossenfelder on her blog, it is very nicely explained:<br />http://backreaction.blogspot.com.ar/2013/01/how-particle-tells-time.html M. J. Glaeserhttps://www.blogger.com/profile/05153269635849920592noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-48277232823272854452018-05-02T13:29:59.075-05:002018-05-02T13:29:59.075-05:00How is it a clock? What are its "hands"?...How is it a clock? What are its "hands"?Alexander R Prusshttps://www.blogger.com/profile/05989277655934827117noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-446709882574287602018-05-02T13:14:15.377-05:002018-05-02T13:14:15.377-05:00Every massive particle is a clock; so your problem...Every massive particle is a clock; so your problem only affects massless particles... except it doesn't either, since it is well known that the proper time is zero for massless particles :) M. J. Glaeserhttps://www.blogger.com/profile/05153269635849920592noreply@blogger.com