Events Definition and 352 Threads

I tried to come up with answers using the spacetime interval equation. (Δs)^2 = (c*Δt)^2 - (Δx)^2 Let train's frame of reference be S. Δt = 0 Δx = 500 m (since proper length is measured in object's rest frame) Then I get (Δs)^2 = -250,000 Since L = L0 / lorentz factor, where L0 is the proper...

For this problem, Does anybody please know how events can be separated by time in one frame and distance in another? This notation does not seem physically correct to me. Thanks!

Is there a formula for this ? Consider the following simple looking problem. We have three contestants A, B and C, there is a competition between them and the best wins. For example a race, discus throw, javelin throw ... We know that A beats B with a probability 0.6, A beats C with a...

I was chating with chatgpt about communites and that time I found Physics forums. Totally a great place for all the physics enthusiast. Great to be here!!!

Hello all: Watching few news , titanic came and we start to have a question , can I prove that titanic was sunk because of hitting an ice mountain, and not because of torpedo, should we use material specifications , speed of the ship , and material specifications of the ice mountain or we...

Exercise: My solutions: For events to be simultaneous, the invariant interval must be bigger than zero (spacelike). I got $$I = -c^2 \Delta t^2 + \Delta x^2 + \Delta y^2 + \Delta z^2 = -(0-1)^2 + (0-2)^2 + (0-0)^2 + (0-0)^2 = -1 + 4 = 3 >0$$. Which is indeed greater than zero, to find the...

This thread picks up a discussion between myself and @A. Neumaier in another thread. In particular, this comment: Reference: https://www.physicsforums.com/threads/nobody-understands-quantum-physics.1049370/page-8 First some basic background. If we consider the usual presentation of a...

Oddly I remember having read about these events before (beginning of) year 2020. murder of George Floyd: https://en.wikipedia.org/wiki/Murder_of_George_Floyd Kenosha unrest shooting: https://en.wikipedia.org/wiki/Kenosha_unrest_shooting Capitol Hill Occupied Protest...

From my limited understanding the Galilean transform has 2 frames but 4 four perspectives. For example x is the stationary frame when using ## ∆x = ∆x′ + v ∆t ## and x' is moving. When using ## ∆x' = ∆x - v ∆t ## and x' is stationary and x is moving. Now lets use the example of ## ∆x = ∆x′ + v...

I read that the gravitational tidal force of a nearby blackhole can twist and tear apart stars, sometimes even in a matter of days. The 'matter of days' part peaked my interest, and I figured I would ask here before looking it up. Have we ever observed any such event in a matter of days? Is...

Hi, I'm having trouble understanding that for time-like events where the order of time is absolute, these events can be in different spatial orders depending on reference frame. Can someone provide an example please? Thank you!

There are 4 players numbered 1 to 4. There is a room with an entrance door to one side and exit door to opposite side. Inside the room, there are 4 boxes numbered 1 to 4. Inside each box, there is a chit containing a number (with equal probability) from 1 to 4 (inclusive). No two chits can have...

I apologise for my very limited understanding of quantum physics: my background is in General Relativity. A wave function is said to represent the probability of a particle being at some point in space/time, and I take that to mean that the probability of a quantum event is a density on...

Hi! I was wondering if there was an equation to plug in a standard deviation value and get back approximately the percent likely hood of getting that sigma (for example 1 sigma would be 33%, 3 sigma 0.27%, etc). Just something that approximates it with algebra, no calculus Thanks!

I am creating a web page that will have several buttons on it. When a button is pressed it will play a tone or combination of tones. With the Google Web Designer application, I can create a simple page with one button on it. I'm able to associate the clicking of that button with "Custom Code"...

Let's say we have 3 events that all have a certain chance of occurring. Each latter event occurring depends on if the prior event occurred based on the chance associated with it. For example, if Event #1 does not happen, Event #2 cannot happen. As such, if Event #2 doesn't happen, Event #3...

Below is my attempt at the problem. I used the distributive law and applied to what was given, (A∪B)∪Z which equates to (A∪Z)∩(B∪Z). I then applied the 2 set I/E formula to each union. Since there is an intersection between these two sets I added them. But I end up with 2 P(Z) which doesn't...

Given information: A wheel of fortune with ten equal sectors is used for a candidate game. Five of these sectors are labelled only with the number 1, three only with the number 2 and two only with the number 3. The game for a pair of candidates is as follows: The two candidates �K1 and K2...

Humanoid Robots. Just requiring your thoughts on this. Major events,functions example Weddings, Birthday, Anniversary celebrations, Cricket, Football live match etc are captured using Video camera/s with Humans performing the function with later on the captured recorded video is edited with...

(This is a history of science question, so please let me know if it's not appropriate to this forum.) When did someone first realize that major Earth impact events (asteroids, etc.) could potentially be catastrophic? To be clear, I don't mean in the purely theoretical sense (the likely given...

Hello, I have a question about the following sentence and would appreciate if someone could explain how to read out the conditional probability here. "Each microwave produced at factory A is defective with probability 0.05". I understand the sentence as the intersection ##P(Defect \cap...

My wife read an article last night about an outbreak of hemorrhagic fever in rabbits, and it has been passing through populations throughout the US. So, I decided to look into it and came across a wildlifehealth.org. There is a lot of nasty stuff out there. Detection of High Pathogenic Avian...

Hey! :giggle: Give a probability space and events $A$, $B$ and $C$ such that $P [C \mid A]>P [C \mid A \cup B]$.So we want that $$\frac{P[C\cap A]}{P[A]}>\frac{P[C\cap (A\cup B)]}{P[A\cup B]}=\frac{P[(C\cap A)\cup (C\cap B)]}{P[A\cup B]}$$ But how can we find these events ? :unsure:

Hi, If the events A and B are statically dependent then the following formulas are used to calculate conditional probability and joint probability but there is a problem. As I see it both formulas are dependent upon each other. One cannot calculate conditional probability without first...

In Richard Feynman's book "The Strange Theory of Light and Matter", in chapter 2, he explains how to calculate the probability that light from some source will be reflected by a mirror and be detected at some location. He explains how you sum up all of the probability amplitudes (represented...

For letter a), i think that he is assuming that each hypothesis is independent, and that they are mutually exclusive.For letter b), I understand that it indeed admits the relative frequency interpretation, since the the experiment is being produced several times. For letter c) we do the...

One possibility for the ultimate fate of our universe is so called the "big slurp", which to my limited knowledge is some sort of quantum phase transition related to Higg's field (see: https://en.m.wikipedia.org/wiki/Ultimate_fate_of_the_universe OR...

Summary:: problem with independent events in possibilities A forest has a fire per year with probability 30% and it has 2 fires per year with possibility 5%.The probability of 3 or more fires is 0%.The forest might have disasters from the wind which blows with probability of 100% or has...

The three events; t = 0s, x=0 t=1.3s, x=1.3 light seconds t=2.6s, 1.3 light seconds

Let's say you have a leaking tab, and the probability of a droplet in any given second is 1%, regardless of whether there was a drop previously. How would you calculate the probability of n drops in a minute? No drops in a second is 0.99, so no drops over a minute is 0.99^60. Hence one or more...

find the whole idea of modelling real world events involving human beings an interesting intersection of math, science and bull####. The idea of assigning a probabilty to a complex event like an election seems like scientism at its worst. If someone who has studies past elections says ‘my...

I started by finding the main events: Sending the first message Receipt the first message Sending the second message Receipt the second message Now, what we know is the time by ##S'## (comoving frame with the spaceship) ##T_1'## and ##T_2'## remaining to arrive to the Earth measured at...

Hi, I’m looking for ideas and guidance (maybe even formulas?) on making an on-planet situation match a hypothetical solar system. It’s for a fantasy role-playing, but the sentient species must necessarily care (and believably calculate) aspects about their solar system. (However, because it’s...

(1) Uniformly moving frames I begin with a drawing of the situation. The events are labelled as ##\color{red}{E_1}## and ##\color{red}{E_2}##. We note the time of those events : ##t_1 = t'_1 = 30s## and ##t_2 = t_2' = 30+60 = 90s##. I attempt the problem in two different ways. (a) By...

Hi, in general relativity I'm aware of the spacetime 'distance' between two timelike related events is maximized by the free falling timelike path (zero proper acceleration) joining them. Consider now a couple of events belonging to a spacelike hypersurface (AFAIK it is an hypersurface with...

The problem is; You are designing an experiment to search for a new particle. Based on some model, the number of expected signal events is estimated to be 10. In order to claim the signal with the confidence level of 3σ (or 5σ), how small the expected number of background events should be? I...

I've read some stuff on pileup.In one paper, it says the number of inelastic event approximately equals pileup event in detector.I don't quitely understand it.Can someone explain?Thanks

Would like to know what method, or distribution to use when solving a problem like this:I start from level 0. There is a probability p chance to drop to level -1 and a (1-p) chance to increase to level 1. The levels range from level -n to level n. When it reaches level -n or level n, it resets...

Firstly, I calculated the relative speed between the two rockets, finding v=1.6c/1.64. Then, I applied the length contraction: the length of the moving rocket will be 0.6L due to this phenomena, so the total distance traveled by one rocket, with respect to the the other, will be 1.6L. Therefore...

Hello everyone. Let us consider 3 events A,B,C such that: $$P((A \cap B )\cup C)=P(A)*P(B)*P(C)$$ Notice that the second term is a union and not an intersection. Are they independent? And what if the assumption was: $$P(A \cap( B \cup C))=P(A)*P(B)*P(C)$$? I know that the independence condition...

Hello, Sorry if this is the wrong section of the forums, but I figured that questions about mutually exclusive events are relevant to probability. My current understanding: Two events are mutually exclusive if both events cannot occur at the same time. In other words, two events are mutually...

Edit: I'm leaving the original post as is, but after discussion I'm not confused over coordinate time having a physical meaning. I was confused over a particular use of a coordinate time difference to solve a problem, in which a particular coordinate time interval for a particular choice of...

This is an interesting story. I have a couple of friends with kids who need to wear quieting earphones in most public situations, and this seems like a nice way to help families be able to broaden the events that they can attend together. It will be interesting to see if it catches on as a...

1. Which organization or group of organizations is it the responsibility of to detect and track worrisome asteroids? I believe NASA and the USAF track such bodies if I'm not mistaken, but how many others are there? Who is "best" at it, or most relied-upon for spotting and cataloging them? 2...

Suppose someone randomly went to Starbucks Monday thru Saturday between 8:00 AM and 10:AM. Suppose one Tuesday in May they purchased a drink and the credit card transaction occurred at 9:14:12 AM. What are the odds that person could randomly return on a Wednesday in July and purchase a drink...

I have six events with known probabilities ##p_1, ..., p_6##. Find the probability of two or more of these events occurring together? I can't think of a clever way to calculate this without using the problematic "or" is addition rule, but using that rule I get the required probability is P(2 or...

The dude in this video appears to say that "space" (ie a coordinate system that does not involve time ) describes where an event happened but not when. To describe when and where an event happened you need both space and time so if I don't care "when" an event took place, only "where"...

A questionnaire survey on the use of SNS was conducted for students at A University. As a result, we got the following: ##55\%## using Twitter , ##53\%## using Facebook , ##20\%## using Twitter and facebook both, ##19\%## use both Facebook and Instagram. ##76\%## use at least Twitter and...

Popular science: https://phys.org/news/2019-05-scientists-early-moment-megaquake.html https://advances.sciencemag.org/content/5/5/eaav2032 Image courtesy University of Oregon. 15 seconds into a massive event, there is data to support the concept of a warning of a coming massive event. Data...

I'm doing some exercises about special relativity and one of them asks to find the speed in an arbitrary frame of reference (1) in such a way that it perceives two events at the same time that didn't happen simultaneously in other frame of reference(2). Is it correct to state that if the...