Events Definition and 357 Threads

Dear PF Forum, I have a question regarding Quantum Entanglement. I don't know much about QE, but there's something that I want to know. Two particles are entangled. Blue line is the world line of Particle A See Pic 02 Particle B travels according to Green line. And at E1 Particle B's spin is...

What is the "proper" way in python to share information between events? I'm mostly just playing around atm. I'd like to compare the most position between a EVT_LEFT_DOWN and EVT_LEFT_UP events I can use the class to store the information, but that seems a bit sloppy. Is there a better way...

We all know how classical interference of waves can be produced by the Michaelson interferometer using the beam splitter and the detectors. No other elements needed to produce classical interference of waves. Setups like this one which create quantum entanglement http://arxiv.org/abs/1212.6136...

If general relativity, space and time are postulated as a 4D non euclidean space that exist absolutely. All past, present, and future events are static moments in this model. In this model, the present moment can access and has knowledge of past events, but cannot access or have knowledge of...

I'm trying to reconcile yesterday's announcements with the rumors that have been reported. I and others have heard rumors of three events. Yesterday they reported on the event from 14-Sep-2015, and the paper LIGO-P1500217 titled "The Rate of Binary Black Hole Mergers Inferred from Advanced...

Hello, I am studying independence of events and I came across a formula that I don't understand. It is rather technical, not very interesting, but I feel stuck and it stays in my mind. Could you explain the following : If ## (A_i)_{i\in I}## is a sequence of independent events on...

Hi, I was wondering, in the einstein train example, the observer who is on the ground and not moving sees both lightning bolts strike the train at the same time, while the observer who is on the train sees one bolt strike before the other. However, if there is another observer on...

So I new to probability and need someone to help me out if you could. I wanted to look into the probability of a process being complete if each operation of the process has its own likely hood of success or failure. I know that I should be using a binomial distribution to study the process...

I had a question, but finally cracked it. I apologize for the post. What I did eventually, I realized that the sum of two events intersections (A and B, A and C , B and C) is equal to 0.18-3*0.08. I then used this sum in the union formula and found my probability. Hello, I am working on this...

In SR, an event is a particular point in space and time.For simplicity, we only use one dimension of space. We have x'=γ(x-vt) if when x, t = 0 , x', t' = 0Let's say we have a bunch of inertial frames, all moving at different speeds, but all sharing a common origin x, t = 0 From the POV of...

Homework Statement An only child Urška puts 3 pieces of paper into a bag : on each piece of paper is written a name of one of her classmates :David,Niko,Dejan (those are the 3 names): She then randomly picks 2 pieces of paper from the bag and checks them Match the statements on the right with...

So let's say there's a train and according to the passengers on the train the trip takes a time t to go from the station and back. According to an observer at the station, would they measure a time interval of gamma *t or t/gamma? I know they both should see the others clock ticking at a...

Homework Statement Two cards are drawn in succession without replacement from a standard deck. Show that the events A = ”face card on first draw” and B = ”heart on second draw” are independent. Hint: Write A = A1 ∪ A2, where A1 = ”face card and a heart on first draw” and A2 = ”face card and...

Hello, I'd like someone to double check my maths please, it wasn't the greatest at school and that was a few years ago! If I am incorrect could you please tell me the correct answer as well as show me how to apply it so I can figure out similar problems myself. Thanks. Yes, this is about...

Hi, I was just wondering if the following can be viewed as an explanation for randomness in quantum events. My knowledge of quantum physics is not all that good. I've got a bit of philosophical bent, which is the source of my interest. Anyways... Assume that when particles interact, what...

I decided to re-visit special relativity and spacetime. All went well until I reached the subject of time-like and space-like events and their relation to causality. Time-like Events The residual spacetime value between two time-like events is defined as: ∆S = √(c∆t)^ - ∆x^2, where c∆t > ∆x...

I have several different patterns in my sheets. I use these patterns to determine whether the next number will be even or odd, go up or down in those cells on my sheets. Most of the patterns in columns STUV will mirror image themselves when you look at them. I attached a sheet with the...

Dear PF Forum, What does "at the same time" mean for two observers? I've read https://www.physicsforums.com/threads/criteria-of-simultaneity.699560/. But I want to ask a simpler question. 1. Does "At the same time" mean different for two COMOVING observers than two REST observers? And about this...

I have been reading these notes: http://isites.harvard.edu/fs/docs/icb.topic455971.files/l10.pdf in which they claim that if two spacetime events are coincident in one frame of reference then they are coincident in all inertial frames of reference, thus spacetime events are absolute i.e. they...

First of all, sorry if this is in the wrong forum, wasn't quite sure which one to post it in given the question. My question is, given two space-time points ##x^{\mu}## and ##y^{\mu}##, if the events that occur at these points are simultaneous, i.e. ##x^{0}=y^{0}##, are the two events...

In a new experiment done,an Australian team of physicists have said they have said they had a particle in the future affect the past. https://cosmosmagazine.com/physical-sciences/time-travel-and-single-atom

Homework Statement Prove that[/B] P(\cup_{i=1}^n E_i) \geq \max_i P(E_i) (1) for n≥1 Homework Equations I know that P(\cup_{i=1}^n E_i) \leq \sum_{i=1}^n P(E_i). The Attempt at a Solution I know when n=1, trivially P(E_1) \geq \max_1 P(E_1) =P(E_1). So I was hoping I could use induction to...

My question is about foundations of the special relativity theory. In Minkowski's way of presenting special relativity, with a signature "+ - - -", one associates to every couple of events, a spatio-temporal distance which is null on the light cone, positive if the two events are causally...

Hello, I was reading an article the other day regarding measurement and 'Quantum Wierdness' and it made me think about this whole deal with measuring stuff in QM. [EDIT: Article: http://www.anu.edu.au/news/all-news/experiment-confirms-quantum-theory-weirdness ] The thing is I regularly work...

I was looking at what Cohen-Tannudji has to say on compatibility of observables. Assumptions: ## A,B## are operators such that ##[A,B]=0 ## and we denote ## |a_i \,b_j\rangle## to be states for which ##A | a_i \, b_j \rangle= a_i | a_i \, b_j \rangle##, ##B | a_i \, b_j \rangle= b_j | a_i \...

Hello, I'm sorry for the title of this thread, but I don't actually even know what to call this. I'm very bad at probability and statistics in general, but I have the following problem: Events A and B are such that P(A) = 0.3 and P(B) = 0.4. (a) Find the value of P(A ∪ B) when (i) A and B are...

What are some examples of real events that were mistaken for April Fools jokes?

Homework Statement Hi everyone, So I am asked to detect the number of neutrino events that occur from them entering 3000 metric tonnes of pure water. I am given that t=10s , E(neutrino)=10MeV and that the electron cross section is 10^-47 m^2 . This was the famous neutrino experiment at...

In relativity of simultaneity, two spatially separated events are time relative as to the order in which they might occur to the observer (time is relative). However, if the two events are causally connected, the order is preserved in all frames of reference...

Homework Statement Consider three events A1, A2, and A3, and let pi = P(Ai), for i = 1, 2, 3. a) Express the probability that at least one of these three events occurs in terms of the pi ’s. b) Express the probability that at least two of the events occur. c) Suppose that A1, A2 and A3 are...

Quick question about a relativity calculation. Scenario: conveyor belt going at 0.5c. At t= 0 Observer A is on the floor at x = 0 next to, but not on the conveyor belt. Observer A sees Observer B on the conveyor belt at t = 0 x = 0 smashing through a opaque sugar glass pane wearing body clock...

Homework Statement Problem: Given a regular deck of 52 cards, let A be the event {king is drawn} or simply {king} and B the event {club is drawn} or simply {club}. Describe the event A ∪ B Solution: A ∪ B = {either king or club or both (where "both" means "king of clubs")} Homework Equations...

hi everyone, Well we are into a new year and into new discoveries and observations Yesterday morning, Jan 6th, 0548NZST ( 05 Jan 1748UT) there was a reasonable quake in the mountains of the central South Island of New Zealand M 6.0 GNZ ( M 5.6 USGS). Now the quake itself isn't unusual, NZ is...

For two events ##A## and ##B##, where ##A∩B ≠ ∅##, is it possible to deduce from a venn diagram whether or not those two events are dependent? Or is such information unattainable from a mere venn diagram? Also, if we define ##C## as the complement of the union of ##A## and ##B##, why must ##C##...

Homework Statement Three tanks are sent to shoot a certain target. Each tank is to shoot one round. The probabilities of a tank's round hitting the target are 1/2, 2/3 and 3/4 for tanks A, B, and C respectively. Assuming independence of A, B and C hitting, find the probability that: a. rounds...

hi guys a double event, 2 x M 7.4 events offshore El Salvador coming in on seismo NOW these are only 1 minute apart The magnitude is a preliminary one and could change UPDATE: they have removed one of the events cheers Dave

Note to moderators: I’m not sure if this topic is mainstream enough for the forum. If you decide to remove it, I’ll understand. Not convinced I've put it in the right section either! I’m sure you’re all familiar with, or will easily understand, survivor bias, which is a form of selection...

Hello everyone :). I'm new here and wasn't sure where to post my physics question so here I am in the homework help section as my question is homework related... The problem I'm having is of very basic nature however I might have some trouble wording it. I understand an event is something that...

If a single letter is selected at random from \(\{A, B, C\}\), find the probability of all events. Recall that the total number of events is \(2^n\), where \(n\) is the number of simple events. Do these probabilities sum to one? If not, why not? This question comes verbatim from a book on...

hi, I need an explanatory difference between timelike and space like events . examples will do, i know the mathematics regards

Hello everyone, I'm new here. I'm a space engineering student and every time I learn something 1000 new questions come to my mind (as usual with science!). Most of my education was from an industrial (practical) point of view, so I feel very, very curious about the science behind the...

Hello Forum, An event is a point in spacetime with spatial coordinates and a time coordinate: (x,y,z,t). An event does not have a duration since it only lasts for an instant t. We can talk about time duration to mean the temporal separation between two different events, correct? In the...

I was looking at some space-time diagrams with the simultaneity surfaces for moving inertial observers in SR and looking at the picture an interesting thought came up to my mind. It is known that the causal structure of the universe is preserved in SR, and that cause always comes before the...

I've heard that a changing magnetic field creates an electric field and vice versa. So if shoot an electron in a straight line, it would create a magnetic field in a circle around it. Let's say the electron is moving quickly down a road. But there is another particle moving exactly the same...

i have drawn the venn diagram for the question... i am not sure it's correct or not. the question states both are independent events. i don't understand the working in part b ... for me , my ans would be p(A) +p(B).. correct me if i am wrong. thanks in advance.

Homework Statement A meter ruler moves at velocity u to the right past a stationary observer. The observer is at (0,0) in his rest frame. Give the (x,t) co-ordinates of the following events. 1. The right end of the ruler passes the observer (in the observer's frame) 2. The left end of the...

The situation I am considering is that of a single photon directed at a target (say a photographic plate). My understanding is that the wave function for this system (determined by the whole context of the experiment: photon properties, nature of the target, boundary conditions etc.) gives a...

It is often said that we basically live in the past, since it takes time for light to travel from objects to our eyes and we perceive the world as it was. If we measure the distance and speed of light we can discover by how much are we 'living in the past', or when did some event happen...

Sea and Sky does this the best. Here are the expect events for the next several years. Feel free to post a new thread for one you are interested in discussing. http://www.seasky.org/astronomy/astronomy-calendar-current.html

Homework Statement A train is moving by a stationary observer, Bob, at 0.8c. An observer standing still in the middle of the train, Alice, measures the distance to each end of train as 9*10^11 m. Two lightning bolts hit each end of the train simultaneously, as seen by the observer at the...