Time Definition and 1000 Threads

Why do we use the equation ##\frac {1}{2}mv^2 = \frac {GmM}{r}## to derive potential velocity, and then put that in the Lorentz factor in order to derive gravitational time dilation? Shouldn't we be using the relativistic definition of kinetic energy -> ##mc^2(\gamma - 1)## to derive the...

Quantum fields have wave functions that determine a particle position in space. It solves non-locality, double-slit paradox, tunnel effect, etc. What if the wave function is also in time? Won't it solve the breaking of causality at quantum level? (Delayed Choice/Quantum Eraser/Time) Not much...

Is my solution reasonable? What I got from my first attempt is that the time constant won't change. WHY? Because when we double the number of loops (N) we're going to have new values for both the self inductance and the resistance of the solenoid and so the ratio (L/R) stays the same. Here is a...

Is there some sort of special format of proposal they must put together? Do they need institutional support (from their university, dept. chair, company, etc)? Are there costs involved? Does it depend on the facility? Does anyone know where I can get this sort of information? Thanks in...

I am currently a community college student majoring in Computer Science, and I was placed into Calculus 1. I had to withdraw from this course for two semesters now. My professor advised me that I have "Algebra Issues". With my weaker foundation of Algebra, I plan to take the College Algebra...

I am able to solve the problem however if x was position and t was time how is this problem interpreted? I know, for example that ##\frac{dx}{dt}## tells us how the position of something changes as time changes (or instantaneous change) and an integral gives a net change so to speak.

. The above are some of the typical problems related to Poisson Process. I need to understand the difference between time, inter-arrival time, and arrival time in this regard. Say, we start our counting from 9:00 AM and count up to 10:00 AM. Image-1: arrival process. 1. 1st call comes at...

Hello, Let's imagine we have an infinite plane (or large enough compared to the region of interest and measurements) pierced in normal direction by magnetic field B which is uniformly distributed but time varying. For the sake of simplicity we'll presume the magnetic induction is linearly (and...

The attempt is above

I'm a physics student and science fiction writer, and I've never been to this section of PF before! But I have an idea I think is cool for a novel or short story and I'd like some input on the physics involved. As I'm not overly worried about this idea being stolen I'm going to provide a short...

Problem Statement I was watching a YouTube video regarding the calculation of expected return time of a Markov Chain. I haven't understood the calculation of ##m_{12}##. How could he write ##m_{12}=1+p_{11}m_{12}##? I have given a screenshot of the video.

Hello! It says that the Time Constant of an RC circuit is equal to 100 ms. What is the energy that remains in the circuit after 300 ms? "Nothing mentioned about whether it is in falling or rising edge". The formulas that I have been using are : W = 0,5 (C* V^2) V = V0 ( e^-t/rc ) since I don't...

So I had a topic which I would like to fact check from an informed scientific source. Basically there is an argument about whether or not an object that naturally exists in a fourth dimensional space, would by default have more than countably infinite times the energy of a 3 dimensional Object...

Hi, I have provided a procedure for broadcast for BBT at the following link: https://cs.stackexchange.com/questions/106631/all-to-all-broadcast-on-a-balanced-binary-tree But I am not getting the correct time as asked in the question: Required Timing equation is: ##(t_s + t_w * m* p/2)logp##...

Hi, Kindly consider the Question 4.8 on the following link http://parallelcomp.uw.hu/ch04lev2sec18.html ##t_s## = start up time ##t_w## = per-word transfer time m = size of message p = number of processors The total time for communication for ##logp## steps is: ##T = (t_s + t_w*m) * log_2 p##...

I know that has been discussed elsewhere but never could find for a satisfying answer, so I try this here again. Let us not take into account that an observer (an astronaut or a clock or just let us take both: an astronaut with a clock) falling into a black hole (BH) will be killed and torn...

Could a particle be sent back in time on it's world line? Time is defined by events, but at absolute zero, there is no movement or vibration of a particle - does not time cease to pass then at absolute zero for the particle? If the particle was somehow brought below absolute zero, could it be...

for part 1: t= d/s = 9000/13 = 692.31s for part 2: What i am unsure about is wether or not this is after the initial observation or exactly what they are asking honestly. so i found the relative velocity of the bus to the car and vice vera and came up with: t=d/s = 9000/4 = 2250s however i don't...

Basically how do we know that since it is not possible to see the 4th dimension, is it for simplicity ?

There are quite some pop-sci books (by Greene, Smolin, Carroll and others) that deal with the "nature of time". Why does time appear to flow? Why is there a special moment, the "now"? Does simultaneity in SR imply a block universe? Why time-symmetric laws but a time-unsymmetric universe? Does...

So I am having some hard time understanding exactly the effect of moving near light-speed on time. Most of the examples mention clocks as a way of measurement but I can understand why would a clock which is a mechanical or electrical device for measuring time would be effected with motion. That...

Since for the two events of Samir starting the stopwatch, and the stopwatch reaching 10.0s, Samir and his stopwatch are stationary from his own frame of reference, I said it was the proper time and that delta t0 = 10s. Then the speed of the moving frame of reference was 0.6c. I thought placing...

Watching Dr. Susskind show how to find the time evolution of the average of an observable K, he writes: I can not for the life of me figure out he derived it, and he also did something which I found terribly annoying throughout which is set hbar to 1, so after steps you lose where the hbar...

A 2000 kg truck is resting at the top of a parking lot ramp which is at a 15 degree slope. It is then shifted into Neutral and starts moving. How long does it take the truck to get from A to B in seconds? There is a 15 degree slope on the ramp. uk is 0.08 Assume there is no air resistance.

Hey all, it's been awhile since done any calculus or DE's but was trying out some modelling (best price price per item for bulk value deals as a function of time and amount), in the last line i have f(n,t) implicitly. Any pointers or techniques for solving such things?

In this paper ##J=\frac{\partial f_1(X_1)}{\partial X_1}\frac{\partial f_2(X_2)}{\partial X_2}\frac{\partial f_3(X_3)}{\partial X_3}## where ##f_2(X_2),f_1(X_1),f_3(X_3)## evolves with time. Now using this ##\dot J=\frac{d}{dt}(\frac{\partial f_1(X_1)}{\partial X_1}\frac{\partial...

Hi, as Easter is slowly approaching, I came up with an egg cooking thermodynamics problem that I would like to solve. My formulation of the problem including necessary simplifications is as follows: Let's assume that an egg is a sphere-shaped solid body made of homogenous material (ignoring...

So, I have this idea for the FTL engine for artistic purposes and I wanted to ask if anybody could point out it's flaws. I would greatly appreciate if you were willing to discuss them further. It is just a rough summary, so if you want me to disclose more details, ask away. The idea is as...

I want to compute the fraction of time both particles spend outside the finite potential well. All I can get is the probability to find them outside. The wavefunction outside the potential is: $$\frac{d^2\psi}{dr^2} = -L^2 \psi$$ Where: $$L = \sqrt{\frac{2mE}{\hbar^2}}$$ Solving the...

If a Lagrangian has explicit time dependence due to the potential changing, or thrust being applied to the object in question, how does calculus of variations handle this? It's easy to get the Lagrange equations from: δL = ∂L/∂x δx + ∂L/∂ẋ δẋ What is not clear is how this works when t is an...

Long time reader, first time posting here in physics forums. I know that according to relativity photons have no proper time. I also know that a photon of sufficient energy can interact with a nucleus's nuclear force via the weak interaction resulting in pair production. I was looking at a...

Homework Statement The graph shows the variation with time t of the acceleration a of an object (graph attached). What is the change in velocity of the object in the time interval 0 to 4s? Homework Equations a = v/t The Attempt at a Solution My initial answer was -8 m/s, by simply finding the...

I'm not a Physicist, I just have this question that has bothered me for a long time. This came up again recently when I was listening to some people talking about evolution. We know the universe is expanding, and we know that time is stretched with it. So if I'm looking back a million years...

Homework Statement The astronomer fell into the well. The well is circular, depth H = 15m, radius r = 1m. The astronomer has eyes at h = 1.75m. Observation is from the well axis, refraction is neglected. How many % of sky can an astronomer see at one time? How many % of sky can an astronomer...

I've got the start of a plot forming in my mind, and I'm wondering if it's likely to be supported by physics at all. My basic understanding: when astronauts go to the International Space Station, due to the speed at which it is travelling, time passes ever-so-slightly slower for them. This...

Homework Statement I need to find the time it takes a load to reach the end of a distance. Velocity and acceleration are also given. Homework Equations I was thinking of using t=vf-vi/(a) but this does not incorporate distance which I already have. I would use the above formula to calculate...

I just watched a physics show that claimed future outcomes can determine past possibilities for subatomic particles. It was Through the Wormhole - Can Time Go Backwards? (Time index 9:18 to 14:33). I hope it's ok to post that link in here it is a cable TV show, moderator kill my link if not ok...

I would like to know what the implications of this paper are https://arxiv.org/abs/1712.10057. They say " Here we show that, while in nature the complex conjugation needed for time reversal is exponentially improbable, one can design a quantum algorithm that includes complex conjugation and...

Homework Statement Homework Equations Rth = R||R+R (not sure?), τ=Rth*C The Attempt at a Solution [/B] So, what I ultimately wanted to determine is the time constant of this first order op-amp circuit. I first tried to calculate the thevenin resistance seen by the capacitor by using Rth =...

Ok so I've got a question after walking through the time dilation derivation that used 'light clocks' (think a beam of light bouncing back and forth between mirrors) to derive ##\delta t^\prime = \frac{\delta t}{\sqrt{1-\frac{v^2}{c^2}}}##. So my Q is could you derive the same equation if you...

Homework Statement A positive charge ##q## is fired head-on at a distant positive charge ##Q## that is held stationary. It comes in at speed ##v_0## and comes to an instantaneous halt at distance ##r_f## away from Q. What is the amount of energy radiated due to acceleration in this time...

I saw this question on special relativity on the internet: "A spaceship traveling to Alpha Centauri, at 0.95C it takes 4.5 years to get there as measured on Earth.how long does it seems to the spaceship passengers?" the answer was 1.4 years (Lorentz factor of 3.2). this answer makes no sense...

I've been searching and it seems I am not smart enough to find the solution for this... Let say I have a fully closed box made of concrete left in air. The pressure inside the box is 0.01atm. Since it is left in air, the air will come inside the box through concrete walls(since concrete is...

The set-up of the system is like the following: The thing is, a weight was attached to the meter stick and it was placed in different locations. Then the system composed of the meter-stick and the added weight was then released and the time it took for the meter stick to hit the floor was...

In Classical Mechanics, waves produced in linear systems, like EM waves, obey the Superposition Principle in which the wave amplitudes of, say two input waves, “add up” to create one output wave whose varying amplitude is the sum of the two input waves. One example would be Young’s Double Slit...

Homework Statement A person of mass ##m## stands at the left end of a boat of mass ##M## and length ##L##. Both the person and the boat are initially at rest. The coefficient of kinetic friction between the boat and the water is ##\mu##. If the person starts moving to the right, what is the...

My question is this: is the CMB constant or might it be changing with time?

Our 4-D space is ##x^1,x^2,x^3 ,t##. Our sub-manifold is defined by ##(x^1,x^2,x^3)## Therefore for this sub-manifold to be maximally symmetric and for which the tangent vector ##\frac{∂}{∂t}(\hat t)## orthogonal to this sub-manifold The metric becomes...

I have this friend who praises my intelligence sometimes. She always talks about how I'm "really smart" because I get good grades in college. Whenever she praises me, I cannot help but groan silently, because the main reason that I get good grades is because I don't take that many classes per...

This is probably common knowledge to relativity aficionados but at Example 7.3 in this paper: https://www.farmingdale.edu/faculty/peter-nolan/pdf/relativity/Ch07Rel.pdf I was surprised to read the author showing that a ship accelerating at 1g from rest for 1 hour and reaching a speed of...