imatfaal

I see - I had assumed wrongly that timing accuracy would be greater than that. Not sure why I would assume that - it is just that fineness of measurement always seems to me, as a layman, to be of unimaginable accuracy; so it is difficult to believe sometimes that you guys cannot just up the accuracy to almost any desired level (short of indeterminacy etc).

Delayed choice measurement experiments have been undertaken with over 100km between particles http://www.pnas.org/content/110/4/1221

! Moderator Note RiceAWay's hijack has been split off to a new thread of its own. This thread is discussing a new specific report - it is not the place for general discussion / blanket denial of the phenomenon. Do not respond to this moderation within the thread - and please try to stick to the topic. If you think your response might be at a tangent or off-topic then open a new thread

Yes to an extent - lots of these delayed choice quatum eraser experiments (dcqe) work by coincidence matching; so the paths are measured to astonishing accuracy such that signal and idler photons can be matched by timing coincidence (you check this is working well before you start any interference / quantum effects testing). So whilst the travel time is not directly measured (spontaneous parametric down conversion is inherently random so we do not know which input photon will become two entangled output photons) whilst the dcqe is being run; it is measured before and checked in every result. If the travel time was not what was expected we could not run the experiment in the first place

Haven't a clue what that video is meant to show. But your equation is still foolish - it only works for constant acceleration, what you have as time (t) is change in time (delta-t), and it doesn't always work; F=ma and the other equations of motion apply in all classical mechanics at non-relativistic speeds - yours falls over very quickly. OK - so take the mass going 10m/s and apply 0 newtons of force for ten seconds, or apply 10 newtons for zero seconds. You could - if you really wanted to - write F * (t1-t0) = m * (v1-v0); but this cannot deal with, for example, an acceleration which varies with time. So what we actually write is F=ma or F=m (dv/dt) or F= dp/dt

Rubidium Fountains can already exhibit mid 10^-17 of a second accuracy/stability for periods of a year - if I have read the paper correctly https://arxiv.org/abs/1607.06776 These are functioning atomic clocks used for practical purposes BTW - note the author

Sorry but Fresh is completely correct (as was Daecon a few posts ago) - the question in the OP is poorly formed. One always lies the other always tells the truth - if vague prevarication is allowed then nothing will suffice - but if (as is normally assumed) you will get straight answers then any factual question (to which the answer is known)will get you a solution. It is only recursive / reflexive questions that suffer from a problem. This problem normally requires you to find a piece of hidden knowledge - which door has a tiger behind - in addition to the problem of the liar and the truth-teller. The trick is normally to form the question in such a way that both brothers will answer identically - but when no other information is needed then the trick is to form a question that they will answer differently but predictably; any simple pre-known factual question will do

Unfortunately, that is because you do not understand enough of the basics to realise when your arguments have been correctly countered. You would be much better off starting with the fundamentals of the physics and maths and learning them - from that position you would understand that much of your posting is so far off the mark that it cannot be easily corrected

Regarding speed of transitions from on to off - we can (in very special circumstances) already work with spin flips and the hyperfine transition (which in simple terms is spin parallel to spin anti-parallel). I just don't know the answer to this question - but how quickly can an electron flip? In a caesium atom it can do it just under 10 billion times a second - and I believe that in a rubidium atom it is significantly quicker. The energy levels involved are also miniscule (fractions of an electron volt). Funnily enough the hyperfine transition straddles both branches of this thread; it was deemed basic enough and so unambiguously representable that it was included by Drake and Sagan on the Pioneer plaque. If I remember correctly it is the hyperfine transition time of hydrogen which the plaque uses to provide humanity's notions of both time and distance - the line for distance is 21 and a bit centimetres which is how long light travels for one cycle of transition

One section of correct physics is not enough to make a post acceptable - however, one section (and yours had plenty) with erroneous assertions is enough to make a post unacceptable. You were way off course by the third line of your post; acceleration is the change in velocity over the time taken for that change for simple cases as Sensei has elucidated above; in most cases it is dv/dt as the acceleration is not constant. Most school have and will experiment with gyroscopes - perhaps not quantitatively - can you explain gyroscopic precession? Or even why a linear force on the string of a top will allow it to stand on its point?

! Moderator Note Additional whinge by hijacker also split off - please take it as read that complaints about moderation should not be in the thread.

! Moderator Note Split from other topic and moved to Speculations.

! Moderator Note I have removed Speculative post which seemed to challenge the conservation of angular momentum to the correct forum. Only mainstream physics in the main physic forum please. http://www.scienceforums.net/topic/102483-conservation-of-angular-momentum/

! Moderator Note RiceAWay Would you be kind enough to stop focussing on criticism of other members' posting style, approach, and abilities and, instead, concentrate on the science and the debate. Too many of your 27 posts seem to be targetted away from the science and towards the posters themselves. I remind everyone else that if a poster takes a thread off-topic then the best option is to report the post rather than make matters worse by replying to the hijack. Please do not respond to this moderation within the thread.

! Moderator Note Moved to speculations. Take a few minutes to read the rules and guidelines stickied to the top of that forum

I am not sure if it is an urban myth or not - but I remember being told that the present layout was designed to slow down typists who were over stressing their early typewriters (Olivetti?) When I was a student I supported my habits with audiotyping - I was up at around 90 wpm and some of the old hands were way faster than that (they had machines that sped up the dictation to keep up with their typing) . Frankly, a few months practice and anyone can be fast enough on a qwerty keyboard to avoid any real problems - and the trouble to change would be monumental Court Stenographers can be seriously fast - but they do not use standard keyboards. Dvojak keyboards are/tend to be faster for typing - and some of the two-sided jobbies (you hold the keyboard and all 10 digits are permanently resting on keys) are meant to be the fastest.

Yes that's the sort of thing I meant exactly. And that radio programme sounds like "in our time" - or something equally as good; do you have a link? or name?

! Moderator Note moved to Speculations. You have been told a few times that the role of the observer is not a involved as you wish to think it is - if you want to continue in this vein you will have to be rigorous in your argument and abide by the rules of the Speculation Forum. If you merely wish to assert what you reckon is the case - then there is no place for that here; this is a Science Forum.

Yep - I would guess all dimensionless constants; alpha ~1/137 etc. I did read an article that these might be the limit as it is possible we do not understand how human-based things like Peano axiomata are - ie even what we consider basic maths might not be universal; but the arguments given were over my head and I did think the whole paper was fairly tendentious.

Check your maths - I don't get that answer for [latex]\sum_{k=1}^{k=3}A_k\cdot \cos (2\pi\cdot k\cdot f_0\cdot t)[/latex]

! Moderator Note Thread locked. Please post intelligible arguments or debating points not mere streams of consciousness

! Moderator Note OK - I have had enough. You are just soapboxing and ignoring arguments - you do not get to merely assert your theory's correctness. Last chance to engage (ie provide an argument which starts with agreed foundation and builds to your hypothesis - and NOT a mere claim that your ideas will be shown to be right in the fullness of time) with member's counter-arguments before the thread is locked. Do not respond to this moderation within the thread

lazarus - do yourself (and us) a favour and buy a physics textbook and learn from that. Downloading papers with likely looking titles and hoping you can glean information is a fool's errand.

I think it is arguable that it is the only system of units that could, arguably, be paralleled by alien civilizations (if any) - there is nothing anthropocentric about the Planck units.

Think of a simple situation with s = ut +1/2at^2 and you will understand what the two or one solutions each mean. 1. You are traveling in positive x direction at S_0 metres with a velocity v m/s. 2. You start decelerating (ie accelerating in the -ve x direction) -a m/s^2. 3. Soon after you start decelerating you pass point Y but you are still traveling in +ve x direction 4. Some time later you come to a halt - and if the acceleration continues you start to move in the -ve x direction 5. Sooner or later you pass point Y again - this time traveling in the opposite ie -ve x direction 6. That is the situation you get with TWO roots for an S_Y = ut +1/2at^2 scenario If we take the same first two points as above and posit a new scenario from 3 onwards 3a. Call the point Z where you actually stop (only for a briefest moment) before you start to accelerate back in the -ve x direction 4a. You never ever (with a constant acceleration) get back to Z 5a. This is now the situation with a SINGLE root for the S_Z = ut +1/2at^2 scenario In both questions we were dealing with a "just got there" or "just stopped from crashing" These indicate you were at a turning point - ie the point of intersection was the minima (or maxima) of the parabola; and that is just a single point. I will take a look at your solution and see what went wrong later OK - the reason this doesn't work is you do not need to decelerate to zero - just to 29 km/h http://www.wolframalpha.com/input/?i=(145%2F18)(-660%2F(18a))+%3D+(805%2F18)(-660%2F(18a))+%2B+0.5a(-660%2F(18a))%5E2+%2B+676 That gets the same answer as me That's a different approach from mine - I like mine better because the solution is easier maths ; but yours is probably the way it was intended to be solved