What is Clock: Definition and 483 Discussions

CLOCK (Circadian Locomotor Output Cycles Kaput) or Clock is a gene encoding a basic helix-loop-helix-PAS transcription factor that is believed to affect both the persistence and period of circadian rhythms.
Research shows that the CLOCK gene plays a major role as an activator of downstream elements in the pathway critical to the generation of circadian rhythms.

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  1. Tom MS

    I Resonant Frequency of an Atom in an Atomic Clock

    Beam standard atomic clocks work by changing the magnetic state of a cesium atom by applying a microwave frequency that matches the resonant frequency of a cesium atom. What is this resonant frequency of the atom in terms of actual events that occur on the atomic level...
  2. D

    B How can a light clock tick once per meter even when in motion?

    Hello P.F. I have previously raised the idea of a light clock that ticked each time the light traveled one metre. Dale has said if I could explain how it could be done, I could open a new thread. Here goes. A normal light clock ticks each time the light goes mirror to mirror. I propose a light...
  3. S

    B Moving clock as seen by an observer at rest

    Please forgive me if this has been asked before. I understand that a clock that is moving relative to an observer at rest will slow down. If the moving clock is in a transparent rocket, would the stationary observer on the ground see the moving clock slow down physically?
  4. D

    I Light Clock Problem on the Train: Exploring Time Dilation in Special Relativity

    Hello PF. Re. the light clock on the train thought experiment. If the mirrors are one metre apart in both frames. And the speed of light is the same in both frames. Why isn't the time it takes light to travel one metre, the same in both frames? Thanks.
  5. AndroidX7

    Exploring An Innovative Analog Clock Design: Can Gravity Affect Time?

    So I have no form of engineering education, but I had a hypothesis on an analog mechanical clock being able to account for the effect of gravity on time with a form of super-sensitive weight and scale system to control speed. Has this been done? Either way, any thoughts on the matter?
  6. C

    A rocket ship leaves earth at a speed 0.6c. When a clock....

    Homework Statement A rocket ship leaves Earth at 0.6c. The clock of the rocket says 1hr has elapsed. (a.) According to the earth clock, when was the signal SENT? (b.) According to the earth clock, how long after the rocket left did the signal arrive BACK on earth? (c.) According to the rocket...
  7. gjonesy

    News Doomsday Clock fact or paranoia?

    I have just read an article that stated that the doomsday clock is set to 3 minutes to midnight, are we really that close to total destruction? http://abcnews.go.com/Technology/doomsday-clock-time-adjusted-show-close-apocalypse/story?id=36524149
  8. DaveC426913

    Are clock radios particularly frangible?

    The two clock radios in our bedroom both kaffed it recently. It is entirely possible that they both kaffed it at the same time. I did not notice. At first, I thought maybe the clock radios had simply been drained of power too long - when I deliberately had that circuit off for an extended...
  9. Iconoclast

    The Photon Clock Challenge

    A Youtube channel has just uploaded a video proposing a challenge. The question is pretty simple. It can be summed up to: A clock is moving towards you at 50% the speed of light, and eventually it passes you and continues its travel. When the clock is moving towards you, will it appear to tick...
  10. 22990atinesh

    How to calculate Clock Skew of nodes in a distributed system

    A distributed system has 3 nodes ##N_1##, ##N_2## and ##N_3##, each having its own clock. The clocks of nodes ##N_1##, ##N_2## and ##N_3## tick 800, 810 and 795 times/ms. The system uses the external synchronization mechanism, in which all 3 nodes receive the real time every 30 seconds from...
  11. SlowThinker

    Color of light in the Light Clock

    In another thread, I came across the question of how the photon's energy and momentum appears in the moving frame. The question is best explained with the standard light clock. Lets have 2 horizontal mirrors, that is, one above the other. In the rest frame, the photon is set up to be linearly...
  12. D

    Time Dilation and different clock types

    Hello PF. A moving clock is seen by the platform observer to run slow. This applies to all clock constructions. A light clock runs slow because the light path lengthens and the clock takes longer to tick over. Other types of clocks don't have a light path to lengthen. By what mechanism do...
  13. D

    I Understanding Light Clock Confusion on Moving Trains - A Discussion

    Hello PF. Sometime ago I posted a question about the light clock train thought experiment. I didn't understand the answer, so if I may I'll ask it again. In the light clock on the train thought experiment, the clock is calibrated to each time the light strikes the mirrors, which are 1 metre...
  14. J

    Smallest possible spinning clock?

    The Earth's rotation acts as a clock and defines a rather precise unit of time called the day. We could go out in outer space and spin a marble and get a reasonable clock. On the other hand, it is my understanding that you can't do this with an electron, that is, you can't start an electron...
  15. C

    Length of Sides of a clock

    Homework Statement I'm trying to create a clock face in Python and can't quite figure out where I'm going wrong. Statement: For a clock of radius 100 units, what will be the distance between two adjacent numbers? If a turtle walks along the path joining two adjacent numbers, by what angle...
  16. Ygggdrasil

    News 9th Grader Arrested for Bringing Homemade Clock to School

    http://www.dallasnews.com/news/community-news/northwest-dallas-county/headlines/20150915-irving-9th-grader-arrested-after-taking-homemade-clock-to-school.ece?hootPostID=532c3696eb235a3f481ed45f733e6d90 Of course, this comes from a city, Irving, TX, with a mayor who has been an...
  17. R

    Moving clock, what exaclty "ticks" slower then the stationar

    I am wondering when people say moving clocks "ticks" more slowly then the stationary clock what exactly is ticking more slowly? Is it the mechanism in the clock itself? Like the actual gears inside the clock?
  18. Phynos

    Two observers must agree what each clock reads....

    Homework Statement You are gliding over Earth's surface at a high speed, carrying your high-precision clock. At points X and Y on the ground are similar clocks, synchronized in the ground frame of reference. As you pass over clock X, it and your clock both read 0. (a) According to you, do...
  19. B

    Understanding the SPI Interface: Clock, Data & Oscillators

    From my understanding of how SPI interface works, the clock basically sends out data when it is set to HIGH(or LOW). So, why does it seem like in pictures of the SPI lines, the setting of HIGH and LOW appears periodically. Can't we just put data onto DATA line, turn CLOCK line on to send, then...
  20. Stephanus

    Measuring Motion: What STAY Knows About TRAVEL

    Dear PF Forum, I'm sorry if I ask the basic question here again. Just need confirmation. V = 0.6; Gamma = 1.25 TRAVEL travels at 0.6c. STAY stays. Pic 02 is Pic 01 boosted -V. 1. All STAY knows about TRAVEL is: Proper Time Speed Is this true? And mutually for TRAVEL 2. At B (and C)...
  21. D

    Alarm Clock & Wiring: Is It Possible?

    Hey All. I want to throw this out there to someone knowledgeable and hopefully I can find my answer here. I had a spat with my downstairs neighbor whose room is below mine. He's been doing things like turning up the TV loud or banging beneath my bed in the middle of the night, etc. One thing...
  22. M

    How to determine which clock runs slower in relativity?

    So I was recently reading Stephen Hawkings' "The Universe in a Nutshell" and came across the famous Twins Paradox thought experiment. My question is, since motion is relative, couldn't we extrapolate that either the observer on Earth is stationary and the rocket is traveling near light-speed...
  23. B

    Physical Pendulum Question (Mass on a Grandfather Clock)

    Homework Statement You are at a furniture store and notice that a grandfather clock has its time regulated by a physical pendulum that consists of a rod with a movable weight on it. When the weight is moved downward, the pendulum slows donw; when it is moved upward, the pendulum swings faster...
  24. L

    Measuring Speed of Light with One Clock

    I know there is a problem with measuring the one way speed of light, but why can we not use just one clock. If somebody could explain the problems with this method, then it might help me to understand. Can we measure the one way speed of light the following way:- Have a long sealed tube with a...
  25. Stephanus

    Measuring distance, speed and clock

    Dear PF Forum, I'd like to know how we measure speed, distance clock in space? ##v = 0.6c \gamma = 1.25## Supposed the distance between A and B is 900 ls. And supposed A and B keeps exchanging signal for 6 seconds interval. Because the distance between A and B is 900 ls, there are 150 signals...
  26. P

    What limits the speed of a computer or cell phone?

    I am just beginning to educate myself about electricity and computers. Every time I read something I realize my ignorance is even greater than I imagined. For instance, I was stunned to learn that the drift speed of a typical current is so slow. An AC circuit generates an electromagnetic field...
  27. G

    Observing from Earth the clock in a spaceship

    Homework Statement A spaceship leaves Earth at time ##t=0## with constant speed ##u##. Its clock is synchronized with the terrestrial one. At time T an earthling reads with an optical telescope the clock inside the spaceship. What value does he read? Homework Equations Lorentz equations. The...
  28. C

    Why the Shapiro delay is calculated with respect to the....?

    Why the Shapiro time delay is calculated with respect to the difference in coordinates and not with respect to the physical distance? I follow the discussion of Clifford (Theory and Experiment in Gravitational Physics) which uses isotropic coordinates and PPN approximation. To make more clear my...
  29. Stephanus

    Clock synchronization: Time Dilation & Reference on PF Forum

    Talking about relativity, time dilation and clock synchronization. What time of reference does PF Forum use? If you see a thread being answered at: "Today 10:00 am" Is it 10:00 am on PF server or 10:00 am on your computer?
  30. Tonia

    Atomic Clock Problem: Calculate Nanoseconds Difference

    Homework Statement An atomic clock moves at 1,000 km/h for 1.00 h as measured by an identical clock on the Earth. At the end of the 1.00 h interval, how many nanseconds slow will the moving clock be compared with the Earth clock? Homework Equations (1/ sqr rt 1 - v^2/c^2) The Attempt at a...
  31. M

    Understanding Light Beam Emissions and SR's Light Clock

    No matter how many explanations of SR I try to read this honestly really bugs me :-) Perhaps someone here can provide a different perspective that will make it click for me, i don't know... The way I model the problem is thus: A C B there being 2 inertial frames, one for A&B...
  32. Andre' Quanta

    Time Misured by Clock in Non Inertial Sistem?

    Starting from the general expression of the metric in coordinates, what is the time misured by a clock in a non inertial reference sistem?
  33. F

    Clock synchronization and relativity of simultaneity

    I addressed already recently in this thread the issue of defining the synchronicity of clocks moving relatively to each other (considering that the synchronization by Einstein's method implies clocks at rest), but it occurred to me now that even for clocks at rest relatively to each other there...
  34. S

    Ans. Speed of Light: Clarifying Experiments & Processes

    Hello everyone! Recently my work has been more involved with high energy physics. I have been looking into some things, and I would like help with an understanding of the speed of light. So far, the main ideas I have seen have been thought experiments, with minor (if any) direction to...
  35. Atlas3

    Does the Universe Have its Own Clock and Period?

    Does Universe Spacetime have clock of it's own? A period?
  36. Stephanus

    Twins Paradox: Exploring Clocks in a Closed Room

    Dear PF Forum, I have a tought experiment here. I'm asking about twins paradox, but instead of using twins, I'm using clocks to lock them up in a closed room. Sort of Einstein elevator. (unlike Schrödinger, even in tought experiment, I can't imagine locking human being -- or cat -- in a closed...
  37. A

    Designing a Gearing System for an Analog Clock: Need Help!

    This task seems to me like it should be rather menial but I can't seem to wrap my head around it. I've already designed a circuit to run an analog clock with components I have already got sitting around my work bench. When it comes to designing the gearing though, I am struggling. My basic...
  38. F

    Speed of light postulate and clock synchronization

    At the beginning of his 1905 paper 'On the Electrodynamics of Moving Bodies' Einstein defined the synchronization between two clocks using light signals, and on this basis formulates the following theorems 1. If the clock at B synchronizes with the clock at A, the clock at A synchronizes with...
  39. Kostas Tzim

    Is my Windows clock not syncing properly? Help!

    Hey everyone ,earlier this day, when i boot my pc i saw that the clock was losing time...i tried multiply times to fix it but again when i reboot the system the problem was still here. i opened bios and i saw that even there the clock wasn't synced...
  40. J

    Calculating Force and Acceleration for a Yoyo and Clock

    Homework Statement A yoyo is spun with a radius of 0.5m. It reaches a velocity of 30m/s. What is the force if the yoyo is 0.3kg? ---- A clock has a hand with 0.3m long and 0.5kg. It takes 60 seconds for 1 revolution. What is its acceleration? What is the force? If you have any tips or...
  41. J

    Atomic clock: energy between two levels

    Homework Statement With the atomic clock a second is defined as the time it takes for EM radiation to oscillate 9192631770 times, which equals the energy gap between two energy levels of a caesium-133 atom. Note: it's a translation and the term used with the oscillation is "oscillation periods"...
  42. Quarlep

    The Light Clock Problem: Resolving Observer Discrepancies

    Lets suppose there's two obsrver O observer is in rest and A is moving with a constant velocity. A observer has a light clock which every click it makes sound.So A observer sees everything normal. Let's suppose A observer heard 10 tics but O sees him moving so O observer will heard 5 tics.But...
  43. C

    Lorentz Transformation - Clock

    Homework Statement Use the Lorentz Transformation equations to derive the formula relating the time period of a moving clock to that of a stationary clock Homework Equations X'=y(X-vt) Y'=Y Z'=Z t'=y(t-vx/c^2) The Attempt at a Solution t'=1/sqrt(1-(v/c)^2) . (t-vx/c^2)
  44. D

    Light clock on Train experiment.

    In the moving frame, relative to the stationary frame, if time is slowed and the speed of light isn't, why doesn't the light travel further in less elapsed time?
  45. M

    Understanding Light's Motion in a Moving Clock

    When light is moving up and down in a light clock, it has no horizontal speed to an observer at rest relative to it. If that light clock starts moving, the light must be moving with the clock because at rest, the light and clock both have no horizontal speed. How does the light convert its...
  46. H

    Time dilation - effect on clock or 'time' itself?

    I understand that this topic have been discussed many times, but I just haven't found the answer, at least one I could understand. I'm not a physicist, just curious. I've been reading all around the internet about time dilation and SR. I understand that time dilation is real, at least when it...
  47. K

    Disk rotating in a gravitational field, like a clock

    Suppose we have a large circular disk with pegs around the perimeter, and we set the disk rotating so that one pegs passes us every second. Then, we move this disk to a gravitational field, such that one side of the disk is closer to the gravitational mass than the other. From our perspective...
  48. D

    Can clock transport tell us anything important

    Clock transport can be used to compare one clock with another in an absolute sense. All we have to do is to transport a clock between two A-frame clocks that have been synchronized per Einstein's definition. Let's call the transported clock "T" and the left-hand and right-hand E-synch'd clocks...
  49. G

    An atomic clock and a normal clock

    Two clocks in a spaceship floating though space at 99% the speed of light. One is a atomic clock and uses light and mirrors to measure time, the other clock uses cogs and gears like a conventional clock. From the perspective from inside the ship both clocks tick and tock at the usual rate...
  50. D

    Time dilation -- light clock on a train thought experiment

    Who first came up with the light clock on a train thought experiment.
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