Observation Definition and 229 Threads

Suppose I have observed ##Z = 3##, where ##Z = X + Y##, where ##X \sim N(0,9), Y \sim N(0,4)##. How would I find the most probable value of ##X## that would have given me ##Z = 3##? My attempt at a solution: I was given that ##X## and ##Y## are independent, so that means ##Z \sim N(0+0, 9+4) =...

I beg forgiveness if this should be in chemistry; to me it seems more of a physics problem. This summer I had two Polyethylene terephthalate (PETE) spice bottles deform due to the sun shining on the clear plastic tub, Polypropylene(PP) in which they were stored. The first time the big tub was...

First of all, from what I've read the descriptions of an observation or measurement in Quantum Mechanics have been quite vague. Since the word measurement is used alternatively I am going to assume that this includes all types of measurements, which brings me to a question. If the box...

Hi, I have a question regarding polymers. You know that polymers, basically, consist of chains of polymers, each chain including number of repeating units (monomer). These chains can be in amorphous or crystalline states. Experimentally, is it possible to fabricate and see a single chain...

Predict! The Day of Judgment (by real observation) is at hand!--Smolin Lee Smolin gave a really interesting talk at this past week's conference on Quantum Gravity at Perimeter. He was assigned a 35 minute time-slot by the organizers, and asked to challenge the audience of QG researchers, which...

From this figure we could see the axis of rotation of wheel is y-axis and it's translational motion is along x-axis How would I describe it's horizontal motion in terms of rotational motion The wheel is spinning and also moving horizontally along x-axis w being the angular frequency

So I am working with a Hidden Markov Model with continuous observation, and something has been bothering me that I am hoping someone might be able to address. Going from a discrete-observation HMM to continuous-observation HMM is actually quite straightforward (for example see Rabiner's 1989...

Dear every specialists, I heard that BICEP2's observation r=A_t/A_s=0.2 n_t=0 indicate two things: 1) n_t=0 excludes ekpyrotic cosmological model (ECM) definitely because ECM predicts n_t=2 2) r=0.2 excludes almost all current string inflation model (SIM) such as KKLMMT because this...

Hello Folks, In the attached graph, I have data logged relative humidity (RH) and temperature within my Hiscox and MBT guitar cases, over a couple of days. Both cases have 50g of standard Silica Gel within them, the room they are kept in is maintained at approximately 60%RH. The Hiscox Pro...

This question is only about formal definitions, so it is only about how we define things. It is probably very easy even though it is kind of long. Most of the time when I have seen a random variable it is used as follows. We have a probability space (Ω,F,P) and a measureable space (E,ε), and...

Off a g+ post: https://plus.google.com/+PeterTerren/posts/Weo9gg8F5d9 The device pictured (see link) is turning away from the dark side so thermal transpiration dominates. Data is a little hazy, ill-defined terms, and there is poor control of variables. But I'd put it down to the the laser...

http://arxiv.org/abs/1305.6946 The GraviGUT algebra is not a subalgebra of E8, but E8 does contain an Extended GraviGUT algebra Andrew Douglas, Joe Repka (Submitted on 29 May 2013) The GraviGUT algebra is defined as the semidirect sum of spin(11,3) together with its positive chirality...

I am curious to know if anyone has any knowledge about a phenomena I observed at a local supermarket recently. There was a display stand base, box like in construction probably two foot x two foot square with objects in a tray on top. It is the base that caught my attention. All the sides were...

Homework Statement Analyse the interruption of solar observation of a satellite on a sun-synchronous orbit (altitude 900km above Earth's surface). The orbit crosses the equatorial plane at the day/night border and the orbital plane should follow this border as close as possible. a) Draw the...

I just found this weird observation in Ragestache Comics. Anybody care to explain to me why one can Retain the troll face even after sometime ?? (Eg. I could Retain the figure in my mind for more than 4.5 mins ).http://cdn.ragestache.com/2012/1/23/ragestache.com_30398_1329012006.jpg BTW, could...

Is there a term to describe the phenomenon that observation seems to effect the outcome of superposition?

How Albert einstein proved this equations that I referred at the title? He proved that with maths or with observation?

Hi Everyone, I am a newbie in probability theory and following is my question: Consider we have two binary random variables A and B. B is dependent on A. So we have two conditional probability tables P(A) and P(B|A) with the following parameters ...

Hi, I'm wondering if there's any possible way to do voltage gating to a sample while observing it with a microscope, in order to measure its optical properties while changing its electrical parameters. Thanks

Hello guys. I am studying the experiment conducted by Chamberlain, Segrè, Wiegand and Ypsilantis in 1955 at Berkeley (using the Bevatron) to observe antiprotons. Here is the article: http://escholarship.org/uc/item/46p0z8w7#page-3 I have some questions. 1) While the desired reaction of...

Hi all, It is my understanding that a Doppler shift is the result of a change in wave frequency due to a change in distance of a signal source, relative to the observer. I assume that the change in distance must be continuous, in order to observe a Doppler effect: frequency increase =...

Hello I am having problems in GR because I do not understand how observations frames work in this theory. I have a few more specific questions. -In the schwarzschild metric, which frame is the metric written in? (The one with swarzschild coordinates) -In the non-vaccum solutions, how do we...

Some questions have been haunting me about this experiment for some time. I'm mainly interested in what we observe from the perspective of the projection screen. First let's imagine that there is only one slit, and we are observing from the projection screen looking back at the slit with the...

Hi, I've done a lot of personal research on the internet trying to understand what exactly is happening in this experiment but I keep seeing contrasting information about what the role of observation actually had on the experiment. What I understand is that when they try to figure out which...

Hi I was day dreaming the other day when I realized how incomplete and vague the fundamental postulates of QM are, I mean what counts as an observation? For example simply being in the presence of a charged particle can be an observation, since (using a point particle for the sake of argument)...

Dear All, If the image we see from a distant galaxy shows how it looked 1 billion year ago, what would that galaxy appear if we are traveling towards it at the speed of light? Do we see the galaxy developing twice as fast? It would be great if someone could explain it with both a simple...

Hello! How do you prepare observations at profesional telescopes? How many objects it is possible to observe during one night? I have to choose an observatory and prepare a proposal (as a homework) and I would like to receive guidance on the steps to follow. Thanks! :-)

I'm reading Eisenstaedt, The curious history of relativity: how Einstein's theory of gravity was lost and found again. In ch. 1, Eisenstaedt says that in the early 18th century, James Bradley at Oxford tried to observe parallax, failed, but detected a much larger effect, aberration, which showed...

Hi. I have a problem to understand the following situation regarding observation of a quantum system: Imagine we have an unstable particle in a box, together with many sensors where each is connected to a lamp. The sensors continuously monitor the particle, the lamp turns on whenever the...

"Many years ago I spent a few weeks on the gaff-rigged topsail schooner Tradewind. I noticed one of the gaffs had a distinct bow in it and asked the skipper about it. He said they were hit broadside on by a rogue wave in sub-Antarctic waters south of New Zealand. The steel gaff had been bent by...

\begin{array}{c}\text{The bee is a very busy soul;}\\ \text{He has no time for birth control.} \\ \text{That's why in troubled time like these}\\ \text{There are so many sons of bees.}\end{array}

I am by no means an astronomer and have no experience whatsoever with astronomy. On the night of July 9th (well it was really 3:30AM on July 10th) I was going to the bathroom and I noticed two very bright yellow lights out in the sky (one slightly brighter than the other). They were easily 20x...

I've read a lot of pop sci books, paul davies, lawrence krauss, leonard susskind, stephen hawking and in just about all of them the first few chapters start out real easy, almost too easy, say on a 10th grade level, then they jump up rapidly to say a 3rd or 4th year college level towards the...

Hello, I have a question or two about gravitational waves. My current job is basically to measure atomic strains using x-ray diffraction. I have managed to reduce the error in measurement low enough to reveal an annual sine wave in my data for a sample which should not contain any strain. I...

Fred Alan Wolf in his book Star Wave - Mind, Consciousness, and Quantum Physics talks about an experiment similar to the double slip experiment where light is a wave when not observed and a particle when it is observed. This one has light coming from a distant quasar with a galaxy between the...

I am trying to plot the flux from an Astrophysical source as a function of time. Due to the nature of the source, I am only receiving a handful of photons in each time bin. So imagine I had 10 observing periods of 10 days each, in which my telescope received the following number of photons...

Homework Statement An observation X has density function: f(x,/theta)=6x/(t^3)*(t-x) where t is a parameter: 0<x<t. Given the single observation X, determine the maximum likelihood estimator for t. Homework Equations Included below The Attempt at a SolutionFor a sample size of n...

There is a train(think of having only two boggie for a claer visualization ) in which two rod which are attached to the front and rear end of the train(say, the length between these rod is the length of the train). These are lowered by a single lever to touch the ground. These rods are at...

Hey guys, I'm a new guy in this forum. I've been visiting it for 1 year actually but never decided to register and so I did. I am having a presentation on black holes at school and I want some clariffication of what's going on when falling into a black hole. Well let's assume that an...

What is the difference between observation and measurement in reference to a quantum experiment?

Hello everyone, I recently had a debate with my philosophy teacher about physics, she was saying that physics is purely an observational science, I objected by saying that some areas of physics are based on reasoning and have no observable results to show, stating superstring theory as an...

Hi - brand new here, so go easy on me! :) I have been considering that the major difference between the observed and the unobserved in relation to the behaviour of light particles appears to be missing something. Every "measurement" device used in the unobserved tests relies on linear...

what is the difference between observation and measurement in reference to quantum mechanics?

Watch this video first, please. ( http://www.youtube.com/watch?v=2ghBUcQG1lQ&feature=related ). I had been imagining magnetism in general as fluid motion and not like it is portrayed now days for the last few years. Disregarding the hundreds of notes and all that, what I did notice was this...

I don't understand why when you make an observation, you need a wavelength shorter than the wanted precision. i.e. you can't make clear pictures of golf balls with radio waves, you can't observe things smaller than a photon with an optical microscope.

Last thread that I initiated was titled `Simultaneity is directional while Time Dilation is not', which presented a scenario for the Non-directional property of Time Dilation in STR. Which I think, needs to be reconsidered. And I believe this is the reason why `STR can only be worked out when we...

in a single particle, double slit experiment is there any way/experiment/argument that can tell if the which-slit decision/finalization is made at the time A or time B below: A) when the photon is observed (by a telescope etc), say a few microsecond after it has passed through the slits...

After watching Brian Green's show on NOVA last night. I was left with a big question that one of you may be able to answer. Brian ended the show by saying that one of the biggest problems that physicists were trying to answer these day is why quantum physics works at a very small scale, but...

i'm using an android smartphone it takes really clear pictures and when u zoom in it shows the picture in great detail and clarity and I'm very pleased with this feature. however, recently i took two pictures and when i tried to zoom in while viewing them they suddenly turned into another...

Derivation of expansion scalar for FRW spacetime -- weird observation In a recent thread... https://www.physicsforums.com/showpost.php?p=3567386&postcount=137 ...I posted a formula for the expansion scalar for the congruence of "comoving" observers in FRW spacetime. When I posted, I...