Time Definition and 1000 Threads

Scenario: Three types of scifi hyperdrives are available to you. Class I: A small drive that can be fitted on small vessels. Hyperspace travel time is a lightyear covered per 30 minutes. Yet in reality, outside 30 days passes for every 30 min of hyperspace travel. So about 2 hours would get you...

with distance between planets as 4x10^8m measured by you on the ship My attempt: t' = γ(t - ux/c^2) γ = 5/3 u = 0.8c t = 0.9s x = 4x10^8m answer is: -0.278 Therefore not possible My question is what if we traveled rightwards, from p2 to p1, would the answer change? Should my above information...

I'm having a hard time understanding how exactly to evaluate the expression} $$\partial_t \mathcal{T}\exp\left(-i S(t)\right)\quad \text{where}\quad S(t)\equiv\int_{t_0}^tdu \,H(u) .$$ The confusing part for me is that if we can consider the following: $$\partial_t \mathcal{T}\exp\left(-i...

Given the example g = \frac{GM}{R^{2}}, we may compute the change in field strength if the mass is changed by a small amount dM to be$$dg = \frac{G dM}{R^{2}}$$and also if R is changed by dR,$$dg = \frac{-2 GM dR}{R^{3}}$$If, however, both the mass and radius are changed by a small amount at the...

Hi, Can anyone please help me with the following: I have found the velocity of projection, no problem, it is v = 2*sqrt(10) Also, in obtaining this value, I have also found the extension in the string when in equilibrium, it is x = 2 Now on to the time of flight. The given answer is: t =...

I able to calculate this 2 things: relative speed of A and B = 3 + 1; 4m/sec Time for meeting for first time in opposite direction = 100/(3+1); 25 sec I can't able to find distance in Meeting for first time for opposite direction.

I have a question relates to a 3 levels system. I have the Hamiltonian given by: H= Acos^2 bt(|1><2|+|2><1|)+Asin^2 bt(|2><3|+|3><2|) I have been asked to find that H has an eigenvector with zero eigenvalues at any time t

First, create a rocket ship with: * a clock * a 3-axis accelerometer * a computer * a 3-axis external thruster The rocketeer begins in Earth orbit and sets the clock to Earth time. Then the ship takes off on a random trip through our universe. The pilot will arbitrarily point and apply the...

That's the website. My dev board image is attached.

Hi everyone, I’m a student in Ireland and I’m still in high school and the teachers were saying that its finally time for us to choose what paths we should take in terms of choosing subjects for our final high school years. Now my main question is that should I become an astrophysicist...

Is this correct? Why the time is minutes instead of seconds? Thanks!

I can show that ##\frac{d}{dt} \langle \psi (t) \vert X^2 \vert \psi (t) \rangle = \frac{1}{m} \langle \psi (t) \vert PX+XP \vert \psi (t) \rangle##. Taking another derivative with respect to time of this, I get ##\frac{d^2}{dt^2} \langle \psi (t) \vert X^2 \vert \psi (t) \rangle = \frac{i}{m...

For instance, if a stream of muons were released from a box near a massive object and traveled on a straight path slowly (at a non-relativistic velocity) away from that object, a faraway observer would notice that the particles would take longer to decay than a muon typically would in empty...

I couldn't match this question with another topic, so I made a new topic. Suppose we have past H and present P at a certain moment. In present P a measurement is made. For matter of speaking we adopt MWI, so we have the two measurement outcomes A and B diverging in two realities A and B in...

do parralel timelines have to run concurrently to our time? what I mean by this is basically if there is a version of me or you out there in a parralel universe right now in 1963 for example just living like normal or do all parralel timelines have to be in the same timeframe as us?

I am assuming this is the interaction picture, so I start with $$|\psi>=c_1(t)|1>+c_2(t)|2>$$. Plugging this into the Schrodinger equation, I get the equations $$i\hbar c_1(t)=<1|H'|2>c_2(t)$$ and $$i\hbar c_2(t)=<1|H'|2>c_1(t)$$. I am assuming H' (the perturbation) is $$H'= − f(t)[...

How did you find PF?: youtube [Moderator: moved from new member intro forum]How did you find PF?: youtube i need a falling mass over time /joules per kilo over 1hr time also need to know how to figure gearing to maintain fall over time in regards to a set resistance such as a 5 kw alternator

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...

I got acceleration by dividing force by m then replaced a by dv/dt and then integrated it to get velocity as a fxn of time and hence got kinetic energy but problem is my ans does not match with any option can someone please compare their ans

vy=vter + (vy0 -vter) e-th/τ where tau=m/b EQ 1 Okay, for part a, I used Eq 1 I let vy=vy(th)=0 --->The reasoning is that the projectile would stop moving for a short time when it hits the incline, but I have a feeling that reasoning is faulty I let vy0=v0sinθ Then the equation became...

Hi, I am struggling with a calculation. A boat costs x to maintain and I and a friend decide to split the costs 60/40, where I put in 60% of the cost. However, I will have the boat less than my friend, he will have it 3/8 of the time and I will have it 5/8 of the time. So what is my actual...

Hi, I'm a 3rd year (Scottish so a 4 year undergrad degree) student doing Physics. Obviously many of you will have been through a Physics/Maths degree and this question is for you. I'm finding that the volume of content this year is so much that I spend all my time keeping up on course notes...

An electric field E(t) (such that E(t) → 0 fast enough as t → −∞) is incident on a charged (q) harmonic oscillator (ω) in the x direction, which gives rise to an added ”potential energy” V (x, t) = −qxE(t). This whole problem is one-dimensional. (a) Using first-order time dependent perturbation...

I actually have a solution available to me, but I don't understand what it's doing so I'll include my attempt at a solution and briefly describe the correct solution that I don't understand. ΔE Δt ≥ ħ/2 (Uncertainty) ΔE = hΔf (De Broglie) ΔE = hc/Δλ Substituting, (hc/Δλ)Δt ≥ ħ/2 Rearranging...

I was not able to derive the charge on the capacitor. But then, I arbitrarily assumed ##\phi=B.A## (Dot product of Magnetic field and Area) Then, proceeding as follows, ##\phi=BA\cos(\omega_0 t)## ##\frac{d\phi}{dt}=−BA\omega_0\sin(\omega_0 t)## Now at ##t=0, \phi=BA\cos(0)=BA## Therefore...

Comparing high precision atomic clocks, one flying in a airplane and one on the ground had demonstrated permanent time dilation presumably due to special relativity (speed) and/or general relativity (gravity) . While similar experiment with a ruler would demonstrate length contraction only...

Hi, I recently learned that if you can travel at the speed of light, or nearly, you can reach the Andromeda Galaxy within 30 years, due to time dilation and bypassing 2.5 million years on Earth. Is this true?

I've already posted this question on the mathematics website of stack exchange, but I've received more help here in the past so will share it here as well. I am developing a tool for missile trajectory (currently without guidance). One issue is that the aerodynamic equations on the missile are...

Recently I've started reading Weinberg QFT, Vol 1, to introduce myself better to quantum field theory, after finishing courses in qft at the university. Reading through the second chapter, I've found myself confused by his treatment of degenerate multiplets in Appendix C. Here is the equations...

If a medium with speed of light ##c_1## is considered, shall the Lorentz transformation be considered relative to it or to speed of light in the vacuum ? I don't know if we could send particles like muons through water for example, to check this with their life time.

Summary: Olympic problem from kinematics Hello, could anyone help me with the following problem? I don't quite get how exactly does it work. After being kicked by a footballer, a ball started to fly straight towards the goal at velocity v = 25m/s making an angle α = arccos 0.8 with the...

Hello, my name is Jack and I'm a year 11 student in Australia. After listening to, and reading some information regarding quantum entanglement, I'm still a little unsure about the solution to a thought experiment: Let's say that I create a situation in which multiple pairs of particles are...

Does paper, for example, old books, or any type of paper that is commonly used, could it trap any acteria/microorganism/virus etc over time?? How to "clean" paper?

I often see the assertion that clocks show proper time. (E.g. this thread). But I don't think that I have seen a good reason for the assertion in GR. It's not a problem in SR because one can always find a coordinate system that is stationary relative to a clock so, from the metric, ##...

I'm an amateur physics enthusiast, and there is a question that's been in the back of my mind for some time that I haven't been able to answer on my own, and haven't gotten a satisfactory answer elsewhere. First, I want to define a couple of terms and make sure my understanding isn't breaking...

Summary: My homework question asks: Consider a simple pendulum, undergoing small oscillations. Is the time average of the tension in the string of the pendulum larger or smaller than mg? By how much? My homework question asks: Consider a simple pendulum, undergoing small oscillations. Is the...

$$C=K\varepsilon_0\frac{A}{d}=C=\frac{(8.85\times10^{-12})\times1\times 0.0254469}{0.01}=0.000022531F=22.531μF$$ 6V*(1-2.71828-t/0.019Ω*0.0000225307uF) time constants 6*(1-2.71828-1) = 6*(0.632) = 3.79 sec 6*(1-2.71828-2) = 6*(0.865) = 5.18 sec 6*(1-2.71828-3) = 6*(0.950) = 5.70 sec 6*(0.982)...

Part A) So, I set the two positions equations of A and B equal to each other since the position has to be the same. A: 0 + 0 + 1/2(2)t^2 = 50 + 0 + 1/2(4)t^2 :B I know I have to solve for time t, but there's no way to solve it with both sides having t^2 so I am not sure which variables I got...

From what I know about (bi-partite) entanglement, we write the combined Hilbert space as a tensor-product of Hilbert spaces for a particle at ##A## and a particle at ##B##, ie ##\mathcal{H} = \mathcal{H} ^{A} \otimes \mathcal{H} ^{B}##. If the particles share a non-separable state, they are...

Even if we manage to travel back in time, according to relativity, we could never travel to a moment before we started our journey, right? So in particular I could not enjoy some moments again with a relative that passed away, say 10 years ago?

As a non-Physics major, like many others, I read science-fiction, hard science-fiction, have undergraduate/graduate courses on Astronomy and college physics. I also participated in R&D that produced electric rockets able to power small space vehicles (very slowly, but surely). I deal with...

Has there been an experiment where 2 particles that are entangled are measured at the same time? If so what was the result? Can any observer occupy the same frame of reference down to an electron? Don't we all exist at different times based on our frame of reference so none of us can share the...

"of the two types of solutions which the Maxwell equations yield for the wave equation, the retarded and advanced potentials, only the retarded field seems to have a physical meaning," let's start please with basic (and detailed as possible for the knowledgeable layman! p.s-which equation is...

If in the early Universe the matter density was density so large causing an intense gravity field, was the time at that epoch running much more slowly compared to the actual time according to the GR? If so then, would any reference frame in the early Universe see the light apparently traveling...

So I've seen many similar questions like this on the internet, but they all involve using Kepler's law, which is not in my syllabus in my case. However, they do give me the mass of the Sun. which I assume involves gravitational force/field/circular motion? The question also gave me a hint that I...

Does the time ordering operator ##\mathcal{T}## commute with the normal ordering operator ##\hat{N}##? i.e. is $$[ \mathcal{T},\hat{N}] =0$$ correct?

Just like a Linux computer can be made to shut down from the terminal using sudo poweroff, a Windows 10 PC can be shut down from the command prompt using shutdown /s. I have, however, seen that Windows 10 takes more time to shut down if the command is triggered from CMD. In my laptop, it...

Double-beta decay will emit two neutrinos. But, are they simultaneously released or separated?

I use the equation ##\psi \left ( x, t \right ) = e^{-iEt/\hbar} \psi \left ( x,0 \right )## to calculate ##\psi \left ( x , t \right)##, and the result is ##\psi \left ( x , t \right) = \frac 1 {\sqrt {2 \pi \hbar}} exp \left [ \frac {ip_0 x} {\hbar} - \frac {i p^2 t} {2m \hbar} \right...

Use the formal definition of Big-Oh to prove that if f (n) and g(n) are nonnegative functions such that f (n) = O(g(n)), f (n) + g(n) = Ω(g(n)). By the definition of Big-Oh: If f(n) and g(n) are non-negative functions such that f(n) = O(g(n)) there must be positive constants c and n0 such...