Time Definition and 1000 Threads

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I tried using equations listed above to get the answer, but I get stuck with a and Vi. What am I doing wrong? The answer is 6.7 seconds.

I watched the movie Time-Lapse recently, which took an interesting approach to time travel. Instead of people/things traveling back in time, information is sent back in time (in the form of photographs). Like conventional time-travel, it still creates paradoxes. For example, if you change the...

Hi PF, A(x,t) is the probability amplitude at time t that a particle is at x. If it was emitted at (0,0) the propagator gives its value. I wonder if QM can give the amplitude of time probability B(y,t) that an impact will occur (for a given y) at any t. consider a screen behind the two slits, it...

In 2016, https://en.wikipedia.org/w/index.php?title=Norman_Yao&action=edit&redlink=1 et al. proposed a different way to create discrete time crystals in spin systems. From there, Christopher Monroe and Mikhail Lukin independently confirmed this in their labs. Both experiments were published in...

1) ##P(X>0.5)=P(Z>0)=0.5## 2) ##P(0.45<X<0.55)=P(X<0.55)-P(X<0.45)=P(Z<1)-P(Z<-1)\approx68\%## 3) ##P(X>x)=0.9\Leftrightarrow P(Z>\frac{x-0.5}{0.05})=0.9\Leftrightarrow1-P(Z\leq\frac{x-0.5}{0.05})=0.9\Leftrightarrow P(Z\leq\frac{x-0.5}{0.05})=0.1## I find that ##\frac{x-0.5}{0.05}=-1.28##, which...

Suppose the Martian sends a signal to Earth, the final flash of which is emitted exactly four minutes later than the initial flash. In that case, with a favorable position of the planets, the final flash on Earth will also be observed neatly 4 minutes later (and 4 light minutes further than at...

Suppose I had a Lagrangian $$L = q+ \dot{q}^2 + t.$$ This has explicit time dependence. Now consider another Lagrangian: $$L = q+ \dot{q}^2 .$$ Which has no explicit time dependence. But after solving for the equations of motion, I get $$\dot{q} = t/2 + C.$$ So I could now write my Lagrangian...

If τ is the relaxation time, τ means, on average the time between two collisions for an electron moving under a constant electric field inside a metal. Now according to the assumptions of drude model, the electron acquires an additional velocity of \frac{-eEt}{m}where t is the time elapsed since...

I've looked it up online and someone did t=40−65=0.15(h) I was just wondering why they would subtract the velocities. Could something explain this to me please? thanks.

Can anyone please tell me why time varying force F is not conservative? That is, what makes a force not depending on the position nonconservative?

I draw this picture in order to solve this problem. My first attempt was find the hypotenuse of the triangle and divide it by the speed of sound wave. d=a/sin(θ) d=4483.43m t=d/c=13.07 sec However, I am not sure whether I did it correctly or not... It looks the time is too big as an answer... I...

This is a problem about converting from the phasor to time domain. I am having trouble following the math that the textbook is doing. I was thinking the final answer should be: i(d, t) = 0.20 cos(ωt + βd + 159◦) - 0.091 cos(ωt − βd + 185.6◦) emphasize the minus 0.091 instead of plus 0.091 as...

When drawing a diagram of the forces acting on the block, I have the following forces: $$\sum F_x = a_x = (g \sin\theta) \cos \theta .$$ Now, I can use the following kinematic equation $$x=vt+\frac{a_xt^2}{2}$$, where $$v=0$$ and $$a_x = (g \sin\theta) \cos \theta$$ $$\therefore \frac{2x}{t^2}...

I’m having quite a bit of trouble understanding time dilation. What will happen if you orbit the Earth close to the speed of light, 1 h passes for you and due to time dilation 2 h on earth. So what will happen when you look at Earth in that hour. Since time passes 2 times faster there will it...

https://www.physicsforums.com/attachments/269029 Lightning strikes A and B simultaneously in the Embankment frame. M' sees the flash at B before the one at A. But if the flashes are simultaneous in the Train frame, does M' still see B before A?

This probably has been asked before but i had a thought about the speed of light and time dilation. First off all i know the speed of light is constant and that it is the max speed anything can be but hear me out. So let's say a jet are traveling from point a to b in space with let's say 0,8c...

To prove: total mechanical energy is constant with time where ##E(t)## is the total mechanical energy and ##V(x(t))## is the potential energy of the object-system. $$E(t) = 1/2 mv^2 + V(x(t))$$ taking the the derivative of ##E(t)## with respect time should give 0. in the third step in the...

photos are in the speed of light which means that the fasts change in photons energy would take infinite time for the outside observer so does it means that the photons can't spin or interact with each other or have any kind of change

So basically i know almost nothing about physics but i have this one curiosity and i hope you can help me ahah. For what i understand if you could move at the speed of light time would stop for you and you would see the whole universe age in a blink of an eye. But what if you could stand...

Hi, just wanting to know the answer to this. What parts of the brain do playing these games stimulate? What effects do playing these games have on the brain? what brain functions do they improve or strengthen? more specifically I mean the games call to power 1 and/or empire Earth 1. Note that i...

Please advise for cooling time on air conditioning. I have a project and customer asked me to make a comparison between their requirement and my proposal. And here's the result. Let's say that we provide a room with same capacity as above, function, delta T, load on that room, but ONLY air...

Algebra in this answer does not seem to flow right. Firstly, the 16, secondly the n term. Can someone explain or show me the right answer?

I tried solving this, the equation coming up is given by: θ≈4 cot^(-1)(e^(-3.1305 sqrt(1/R) t)). However, this is not correct as can be seen when plotted: enter image description here Can somebody please let me know, why is this equation not valid.?

I've seen a lot of Youtube clips and listened to podcasts recently on cosmology and quantum physics and something that has come up frequently that I don't understand is descriptions of time. Specifically Sean Carroll on various podcasts and Carlos Ravelli (when he finally got to the point). 1...

So my doubt is at the beginning of the problems hey are saying that the ball obeys stokes law and on the latter part of the question they are saying that no buoyant force is acting then how does the velocity of the ball change in the end? Also what is the use of specifying 'the ball never...

https://www.asi.edu.au/wp-content/uploads/2016/10/ASOEsolns2012.pdf Q11 D) Markers comments: Few students reached part (d) and very few of those who did realized that the amplitude does affect the time taken for each of Mordred’s bounces. i.e. the energy losses results in shorter periods...

Just read an article about time crystals. I understand regular crystals vary in a routine fashion through space but are unchanged over time. Time crystals apparently change periodically over time. I tried the usual googling but my brain has nowhere to put this. Can someone dumb this down for me?

In the thread is-the-small-world-uncertain-or-is-that-our-perception @mitchell porter said: Can someone explain what "objective universal time" is and what it means for it to conflict with the "spirit of relativity"? Is this an aspect of interpretation where you could describe all events using...

Say that we have an instance where something falls down from a certain height with constant acceleration g. We know that the average speed with regards to the time period is less than (u+v)/2 since we spend less time at the higher speeds. How do we actually calculate the average speed over a...

Earth moves through space in a certain direction at a certain speed. Moving faster slows down your clock while moving slower increases your clock. Does this mean that the direction your moving in has an effect on time dilation? In other words, if you move along with the earth’s initial speed...

All help is welcome!

OK this is a quote from the physics forum site - it is not mine. So the above quote says that there are two effects which alters the clock ticks, the GR effect and the SR effect for clocks aboard satellites. We all know that satellite are in free fall and for free fall there must be a steady...

Consider an observer starting a purely radial free fall from rest at infinity in outgoing Vaidya spacetime - this being a simple model for a radiating black hole. Does anyone have an explicit expression for the coordinate in-fall time (assuming purely radial motion) from infinity to event...

So I stumbled upon this paradox and was wondering what cosmologists had to say about it. For the most part, I take an instrumental view of science. Of course, I accept all scientific histories and truisms as rational touchstone, though I also think we can never be too precocious about the fate...

I notice that in a Schwarzschild black hole, at r=r_{s}/2, the c dt and dr terms are exactly the opposite of what they are in external, normal flat space (Minkowski metric). That is, one gets them by multiplying both terms by negative one. I'm having trouble grasping what this means. An...

Hello all, I studied physics in undergrad aspiring to become a physicist, but I couldn't handle the stress I put on myself to succeed on top of problems I had such as emotional immaturity and bad life habits, etc. I suffered depression, anxiety, and other mental disorders which took me long...

The value of acceleration due to gravity at a depth 'd' inside the Earth is given by- g' = g(1 - d/R) which can also be written as g' = g(x/R) from the diagram so that x'' = (w2)x where w2 = g/R is the angular frequency Hence the time period T is given by T = 2π sqrt(R/g) but the question...

I feel that force is also function of time.

It's just think that if we measure 1 second with a clock we should be able to "see" a 300'000km long piece of something in space or not ? Or does the time extension only has to be understood as a set of numbers indicating timelaps, so that there is no "geometry" of time ?

Can time and space be thought of fields? And if so, how can this affect spacetime? And then what would this mean for affect general relativity?

Radio wave travels at the speed of light 3x10^8 (m/s) Converting the distance to meter: 1.3 x 3.1x 10^16 = 4.03x10^16m The time it takes in our Earth frame of reference is: 4.03x10^16m/3x10^8 (m/s) = 4.26 years The answer is B But wouldn't the time in light's frame of reference be 0 and it's...

Hi this is my first post the forum, nice to meet you all. I am trying to derive the time dilation formula following the image attached. However I am unsure of the algebra being used toget from the 2nd line of working to the 3rd line. Can someone please tell me what the name of the algebra...

I have to derive the Lorentz time transformation given the equation for gamma and the equation for the Lorentz space transformation. I started by using relevant equations from the Space derivation done in class (also the one that Ramamurti Shankar does). Here is a picture of what I have tried...

My understanding from reading about the big rip is that matter itself will be torn, aka ripped, apart in the very last moments of the universe's existence as the expansion of the fabric of space-time mega-accelerates in those last fractions of a second. While the big rip is still a hypothesis...

The point of the twin paradox in special relativity is that the traveling twin experiences a real, frame-invariant effect in which the time evolution of all moving matter is slowed down. If you read a hundred articles and textbooks on SR, you'll see a hundred variations on the message that the...

Did energy begin to exist at the Big Bang? Can energy exist without space and time? Or don't we know? When I've tried to research this I get a mix of different answers. I have virtually no understanding of science or physics in general FYI.

E = (1/√2)^2(E1) + (1/√2)^2(E2) = (E1+E2)/2 Let ψ(x,t=0) = ψ0 So, ψ1 = ψ0*exp(-i*E*T1/ħ) and, ψ2 = ψ0*exp(-i*E*T2/ħ) Given, <ψ1|ψ0> = <ψ2|ψ0> = 0 So, <ψ0*exp(-i*E*T1/ħ)|ψ0> = 0 => exp(i*E*T1/ħ)<ψ0|ψ0> = 0 => exp(i*E*T1/ħ) = 0 Similarly, exp(i*E*T2/ħ) = 0 So, exp(i*E*T1/ħ) = exp(i*E*T2/ħ)...

If time slows down near a black hole then doesn't it stand to reason that time is slower in our galaxy than inbetween galaxies. If that's the case, wouldn't our measurements of distant galaxies be over estimated do to time being faster intergalacticly. Would this time dilation help explain part...