Time Definition and 1000 Threads

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...

{Moderator's note: Moved to Cosmology forum.] Dark matter and the fabric of space time, Can someone with a real knowledge base of physics and the current accepted theories, please explain why the fabric of space is not the candidate for the elusive dark matter? Having read extensively about...

Hej Guys, Did anyone see anywhere an equation to this? If nothing else then a loading time formula for solenoid would do. Thank you!

Is it safe to be exposed to SHF or EHF for a very long time? Like, hypothetically, there was an ear device in my ear that operated in the SHF or EHF frequency band. Would it be safe for me to use it for a long time especially since they're microwave bands(?). Are microwave bands bad for you? I...

Hello, I have a signal and got the FFT result of that. I have shown them both below along with the MATLAB code. May I ask if there is any method to find the time zone(s) in the signal that a specific frequency has(have) happened? The reason I'm asking this is that I want to specify the time...

Homework Statement The problem asks to convert time in minutes to time in hours, and to also calculate the uncertainty for the time in hours.Specifically 10 minutes +/- 0.2min being converted to hours with uncertainty. 2. Homework Equations & 3.The attempt at a solution conversion of time...

Homework Statement Homework Equations CPU Time= Σ(individual IC time) The Attempt at a Solution What I did was first find the integer time, which is 100=75+X, and X is 25. To find the percent reduced, I did 100(1-x)=75+25(1-0.5). This means x is 0.125 or 12.5 %. Is this correct?

Since it's possible to choose a coordinate chart where the Schwarzschild metric components are dependent on time, why that's not done? Would'nt there be a scenario where such a choice would be useful?

Hey, I'm interested in temperature recordings for the last 10 years but also for an estimate in the last billion years, this for hobby and fun. There are a lot of public sources but problem is many sites are torn down and others are created, so I feel very in the wild, it's like finding a tree...

I'd like to know how to solve this. I'm pretty lost as to how to solve this. I want to say that the graph would look periodic because of the graph of the time would go down and then go back up again, but I really don't have anything concrete. The question states: The circular clock has a...

Homework Statement How to calculate time taken (rough approximation) for pressure equalization between two tanks. Both the tanks have same fluid (Air). Homework Equations Rough equilibrium pressure can be achieved by using equations Ptot = (P1V1+P2V2)/Vtot. Thought of using exponential...

Homework Statement For any harmonic load: $$F(t)=F_0\cdot \sin(\omega t)$$ What is the corresponding Frequency domain equivalent? My lecture notes is suggesting: $$ F(t)=F_0 \cdot e^{i \omega t} $$ But I am failing to see how they are equal? The lesson is about Stochastic Response of...

Here's the problem: https://i.stack.imgur.com/rUVvu.png What I did: [2]: https://i.stack.imgur.com/AX2Ye.png [3]: https://i.stack.imgur.com/K1Zbi.png To those who could not understand what I read: So basically I used some geometry to to get $l_1$ and $l_2$ in terms of $r$ and the assumed...

So I see EM radiation , visible spectrum including being portrayed as two sinewave vectors each perpendicular to other one being that of the E field the other being the B field, the field is carried by photons, let's take the visible spectrum as an example. So having a specific frequency the...

Homework Statement "Using the time module, write a program that tells one the current time in hours, minutes, and seconds, and time since January the first of 1970." Homework Equations import time % = mod division int = returns integer value of number The Attempt at a Solution import time...

Homework Statement Two objects ##1## and ##2## move at constant speeds ##v_1## and ##v_2## along of two mutually perpendicular lines. At the moment ##t = 0## the particles are located at distances ##l_1## and ##l_2## from the point of intersection of the lines. At what time will the two objects...

I have been attempting to open up files on NASA’s GRS and neutron data, http://pds-geosciences.wustl.edu/missions/messenger/grs_edr.html but have been running into some roadblocks. The data is all stored in .dat IEEE binary format (which IEEE format they do not specify in their documentation...

Are all arrows of time special cases of the thermodynamic one? The arrows of time I am referring to are the psychological arrow of time and the cosmological arrow of time. Thanks.

[Mentors' note: This thread was split off from another thread about the cosmic ray muon measurements] The particle at rest in the moving ship is moving against the Earth. The particle at rest on the Earth is moving against the moving ship. A scientist in the moving ship measures the life time...

Homework Statement A spaceship of proper length L is moving with respect to the ground with speed v. As measured on the ground, how much time does a light signal need to get from the front to the end of the spaceship. Homework Equations L'=L/γ t'=tγ The Attempt at a Solution The right answer...

In QM, states evolve in time by action of the Time Evolution Unitary Operator, U(t,t0). Without the action of this operator, states do not move forward in time. Yet even stationary states, like an eigenstate of energy, still contain a time variable – they oscillate in time at a fixed...

Hello, I have a 8 gram cartridge of N2O meant for kitchens. Long story short from what I understand it has 10 cm cube of N2O inside. I also know it has 900 psi / 60 bar of pressure inside. The cylinder is exactly like this image. I am trying to find out how much time it would take if I...

Can an expanding balloon be considered a control volume?

i don't understand, how does quantum eraser not imply time travel? i firmly don't believe in retrocausality, but it really does seem to imply it . can someone please explain in layman terms? in here paul davies says observers now can "constrain" the past, does this mean our perception of...

As per my intro post, I don’t consider myself to have any science background beyond high school education. In a philosophy thread about time on City-Data Forum, where most of the entries are just general unscientific musings, I saw the following post: “Time is a distance in spacetime: v =x/t...

How can I calculate the Hubble Parameter in time. I know that it decreases in time and approaches to some constant value but I am not sure to what value, Is there any graph for that ?

Homework Statement Ql: Which sound wave will have its crests farther apart from each other - a wave with frequency 100 Hz or a wave with frequency 500 Hz? Homework Equations Frequency= 1/ periodic time The Attempt at a Solution I did it like that: I just found the periodic time for each...

I have been reading some fairly mind bending stuff about the principle or least time (and those of least action) raising questions about causality and free will. Can anyone explain this to me? Is this total 'woo woo' psuedo science, or are these philosophical questions widely accepted? Thanks...

Homework Statement Homework EquationsThe Attempt at a Solution I have found expressions for the unit vectors for cylindrical coordinates in terms of unit vectors in rectangular coordinates. I have also found the time derivatives of the unit vectors in cylindrical coordinates. However, I am...

Peeling this out into its own thread for clarity: How is time dilation of extreme reference frames (photons, black holes, intergalactic space-time) taken into account in Big Bang cosmology? Since from the POV of a singularity or a photon, their clocks have effectively stopped and any lower...

The current definition of Gravity is: The force of attraction between bodies as a result of their mass. Gravity affects both the space and time of the area surrounding a mass, diminishing with distance, so is the current accepted definition truly accurate? Do I have the correct definition and if...

Homework Statement Homework Equations v = d/t Solve for t. t = d/v The Attempt at a Solution In my General Physics 2 course we are doing sound waves I have the answer to the problem which is 90.8m I am trying to understand the concepts of sound wave. So please correct me if I am wrong, 1...

In Griffiths,Quantum Mechanics 2nd edition,Chapter 2,he gives a problem to calculate the revival time of a wave. Revival time is defined as the time taken by a wave to go from one side(x=0) to other side(x=a). Now let's calculate the revival time with 2 methods. Method 1: Now to go from 1...

Hello! This is probably a silly question, but I am still confused about it and I really don't have any experience with experimental physics. So I understand that a trigger system has a deadtime, which is defined as the time after which the trigger makes its choice, in which no new events can be...

(Apologies I posted this initially as a conversation. Not familiar with the format) I used the ‘gravitational time dilation’ equation to see how the clock rate varies with distance from the center of an object. I got the opposite result to what I was expecting.From Wikipedia; Gravitational...

Consider an electron for which l=0 is kept in a uniform magnetic field B. For which the hamiltonian matrix is {μBB,0,0,-μBB} now if the electron is in the state 1/√2{1,1}(e.g in the eigenstates of Sx eigenvalue ħ/2} If this state is time evolved 1/√2{1,0}exp(-iEt/ħ)+1/√2{0,1}exp(iEt/ħ) where...

So I know gravity correlates with time dilation. If you have two individual equal size black holes close to each other, then at a point between them, gravity is equal to zero. Would the time dilation at that point be a sum of each individual black holes gravity or would the two time dilation...

Let's say I have a client that asks for a file from a remote server that then asks for the file from some other remote server (Let's say Azure Blob Storage, for example). Let's say that the file can be transferred from blob storage to the web server at 60mb/s and from the web server to the...

Hello learned people, I've been looking at special relativity of muons formed in the upper atmosphere... If I can summarise what I do understand (i think)... A muon has 12km to travel to the Earth from the atmosphere at 0.994c. Alice records this as taking 40.2 micro seconds. Now a muon has a...

When people say that time measured from the Earth is equal to time measured from the Sun minus approx 8 min, are they taking into account Lorentz transformations or simply the fact that light takes approx 8 min from Sun to Earth?

I will use 3 way power splitter and power detector. 1. This is power splitter data sheet. In this data sheet, there are different isolation values. What does it mean?? Also in that point, I wonder definition of isolation at power splitter. 2. This is power detector data sheet. In this data...

Hello to everyone, I'm trying to find some data about the relation between galaxy age and rotational curve... until now without success. Are there any teams working on this? Are there any studies in this direction? Thanks!

Folks, I'm back to reading Muller's paper (https://arxiv.org/pdf/1606.07975.pdf) about the flow of time. He postulates that time is expanding similar the way space is expanding (ok... so if you can swallow that). He asks: "why are the new nows created at the end of time, rather than uniformly...

Based on the exponential growth of time dilation 0.0 - 1.0 if given the radius of an object how do you calculate the mass of the object? Time dilation is a function of gravity. Which can be thought of as escape velocity from a gravitational field. So if you have to achieve .866 c to escape...

Homework Statement : [/B] Find the time constant of an inverting op amp with C = 50uF, Ri = 200 Ohms, Rf = 20 Ohms. This is a problem I have found in a prep book for the Fundamentals of Engineering Exam (Electrical component). The book gives the answer as time constant = Rf * C. I am not...

Hello everybody, I've just started studying special relativity and seem to be having a bit of a problem with understanding the concept of proper time. In Modern Physics, by Serway, proper time is defined as the time interval between two events as measured by an observer that sees both events...

I'm armchair knowledgeable about GR, but I've come up against something I can't eloquently explain (to someone who asserts otherwise and wants an unassailable answer). What property results in time dilation even when net gravity is zero?The net gravity at the centre of the Earth is zero, but...

Is anyone did experiment on diffraction with single particle at a time? Do they get diffraction pattern? I referred particle as both electron and photon And I want to know any experiment( classical, or single particle at time) don't show any diffraction pattern in single slit experiment.