Timeline for Why are leap seconds needed so often?
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| when toggle format | what | by | license | comment | |
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| Apr 24, 2018 at 14:04 | answer | added | David Hammen | timeline score: 5 | |
| Apr 24, 2018 at 0:45 | comment | added | user541686 | (deleting some of my comments to clean up...) | |
| Apr 23, 2018 at 23:43 | comment | added | user541686 | @TripeHound: And my point is that would be a wrong assumption. If you literally Google "earth rotation slow down rate" the first article is this Forbes article which says "slowing down by a few milliseconds per day"... and this is an article written by a Ph.D... not in physics. I don't know what articles you read, but every time I've seen a layman article on the topic, it's been in milliseconds-per-timespan like here, not acceleration. | |
| Apr 23, 2018 at 23:26 | comment | added | sig_seg_v | @Mehrdad if you mean your example, 1 meter/sec/sec = .001 meter/sec/millisec. It's not an average over time, we have to look at what is the difference between the rate of speed at t₀ and the rate of speed at t₀ + Δt. | |
| Apr 23, 2018 at 23:18 | comment | added | TripeHound | @Mehrdad What I suspect Emilio is getting at is that the figure the OP quoted probably was produced by a "physics PhD" and the problem arises if you try treating it as something a "normal person" had said. | |
| Apr 23, 2018 at 23:11 | comment | added | sig_seg_v | @Mehrdad That may be true, however, the atomic clock that physicists designed has different issues than the clocks that normal people use. Everyday clocks run at a rate that approximates 86400 sec/day. If your clock runs at 86401 sec/day, then your clock gains 1 sec/day. Atomic clocks run at an exact rate -- put simply, they always run at exactly 86400 sec/day. The earth's rotation is only approximately constant: it is slowing down over time and leap ms are used to correct this deviation. | |
| Apr 23, 2018 at 11:19 | comment | added | user541686 | @EmilioPisanty: No... I'm saying when people (read: normal people, not physics PhDs) talk about clocks running slow, they don't talk about it in terms of acceleration. They talk about the average deviation over a period of time. It's like saying "at my current acceleration I'd go an extra 1000 m in 1000 s".. that means over the next interval of 1000 seconds I'll gain an average of 1 meter every second. You can slice it and dice it however you want ("average 1 meter every second for the next second, or minute?") and get back the same thing ("any interval.. it's average"). | |
| Apr 23, 2018 at 10:00 | comment | added | Emilio Pisanty | @Mehrdad You seem to be completely confused about the difference between a velocity and an acceleration; they are completely different things and you go from the former to the latter by dividing a change by a time interval, i.e. by appending "per year" to the unit. I don't know why you think that addition "changes nothing" but that is dead wrong. | |
| Apr 23, 2018 at 9:29 | answer | added | John McNamara | timeline score: 2 | |
| Apr 23, 2018 at 7:48 | answer | added | hobbs | timeline score: 8 | |
| Apr 23, 2018 at 7:33 | comment | added | dsvthampi | @EmilioPisanty I did make a mistake out of reading 'millliseconds per century'. Now I understand that it is 'per day per century'. | |
| Apr 23, 2018 at 6:10 | comment | added | Emilio Pisanty | @Mehrdad there's 5200 weeks in a century. A clock deceleration rate of 1 second/day/week means that after a century, the clock is losing 5200 seconds every day. A clock deceleration rate of 1 second/day/century means that after a century the clock is losing one second per day. It's really not that hard. | |
| S Apr 23, 2018 at 4:29 | history | suggested | Uzair A. | CC BY-SA 3.0 |
Removed redundant "grammar word" from Title.
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| Apr 23, 2018 at 3:49 | review | Suggested edits | |||
| S Apr 23, 2018 at 4:29 | |||||
| Apr 22, 2018 at 17:23 | comment | added | Emilio Pisanty | Regarding "the slowing down is said to be of the order of milliseconds in a century" - said by whom, and where? What precise quantity is that quote actually reporting? If it's a slowdown rate, a much more natural unit would be milliseconds per day per century - are you sure that that's not the case? | |
| S Apr 22, 2018 at 16:15 | history | suggested | RonJohn | CC BY-SA 3.0 |
Added "grammar word" to Title.
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| Apr 22, 2018 at 15:07 | review | Suggested edits | |||
| S Apr 22, 2018 at 16:15 | |||||
| Apr 22, 2018 at 7:56 | history | protected | Qmechanic♦ | ||
| Apr 22, 2018 at 1:39 | answer | added | Peter Cordes | timeline score: 64 | |
| Apr 22, 2018 at 1:07 | history | tweeted | twitter.com/StackPhysics/status/987860327126663168 | ||
| Apr 21, 2018 at 19:37 | answer | added | Pulsar | timeline score: 42 | |
| Apr 21, 2018 at 18:27 | history | edited | Qmechanic♦ |
edited tags
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| Apr 21, 2018 at 17:50 | answer | added | Steve Allen | timeline score: 0 | |
| Apr 21, 2018 at 16:05 | answer | added | Lewis Miller | timeline score: -5 | |
| Apr 21, 2018 at 15:57 | history | asked | dsvthampi | CC BY-SA 3.0 |