Time Definition and 1000 Threads

If a person was rotating on a verticle axis from head to toe like the Earth or quasar. If nothing can go faster than light, from the person's perspective looking at the stars traveling across the night sky, if you increase the rotation of the earth, stars further than a certain critical distance...

how does the first step use mean value theorem? I don't get it , can anyone explain , thanks.

$$y=2 A \cos 2 \pi\left(\frac{\nu_{1}-\nu_{2}}{2}\right) t \sin 2 \pi\left(\frac{\nu_{1}+\nu_{2}}{2}\right) t$$ Can you explain me the significance of the above equation in the context of waves and oscillations? It's something to do with 'beats,'.

I have been trying to find a time lapse animation showing lunar libration made of actual real photographs of the Moon. However, no matter how much I search, I can only find computer-rendered animations. Does anybody know of a video made out of actual photographs of the real thing?

I had a lamp that was good for 10 years but two years ago it was burnt out, I replaced it and in this two years we have a naughty kid playing with it, it is burnt out recently again. Is it likely due to his behavior (switch it ON and OFF within short time) or quality of light bulb in recent...

how long does it take a 12.5 kg gold bar to melting at 3000 degree C°? Why does the water coming out of the waterjet slow down after a while?

I am confused. My understanding is that proper time is used in 4 vectors analysis because proper time is frame invariant. Every other inertial frame will agree on the same time increment if they use the proper time of that one reference frame. But when you do the Lorentz transformation, the...

In a stressful situation, when you're thinking rapidly, time really does seem to slow down. Like "that was the longest 30 seconds of my life." Since thinking is made up of the firing of action potentials in neurons, could those events, in the brain, work with relativity to slow down personal...

I don't understand why my solution is wrong. Here is my solution. $$ r_{\theta} = R\cos{\theta} \vec{i} + R\sin{\theta} \vec{j} $$ $$ v_{\theta} = v\cos(\theta + \frac{\pi}{2}) \vec{i} + v\sin(\theta + \frac{\pi}{2}) \vec{j} $$ $$ p_{\theta} = mvR(-\sin{\theta}) \vec{i} +mvR(\cos{\theta}...

How to Judge original time and original length of special relativity

Hi, I was reading this insight schwarzschild-geometry-part-1 about the transformation employed to rescale the Schwarzschild coordinate time ##t## to reflect the proper time ##T## of radially infalling objects (Gullstrand-Painleve coordinate time ##T##). As far as I understand it, the vector...

The variation with time t of the acceleration a of an object is shown What is the change in velocity of the object from ##t=0## to ##t=6##? A. ##6ms^{-1}## B. ##8ms^{-1}## C. ##10ms^{-1}## D. ##14ms^{-1}## So apparently the answer is B, which I am having trouble reconciling. Using methods...

When analysing the time-complexity of an algorithm I was told to assume that a hash map is ##0(1)##. A cursory google search afterward revealed that this is true because the time complexity of the hash function is independent of the size of the hash table. That seems alright but if you have a...

Viruses become less deadly/virulent over time?

Find the question below; For part (a), i used the graph to find ##t=22## For part (b), i considered the points; ##(8,20)##, ##(13.333,20)## and ##(0,0)## it follows that, Area=##\sqrt {25.454(25.454-21.54)(25.454-24.036)(25.454-5.333)}## ##\sqrt {2842.58}##=##53.31## There may...

This is the problem; I tried using; ##s##=##ut##+##\frac {1}{2}####at^2## and ended up with, ##240## =## 12t -1.5t^2## clearly we have an imaginary solution here and therefore this may not be correct? My wild guess is that the least time (Without deceleration) should take at least...

Now this is a textbook example with solution. I understand working to solution...my only reservation is on how they used acceleration. The cyclist, i understand was traveling at a constant acceleration of ##2## ##m/s^2## before reaching the top part of the slope. Now, if he is descending...

Hey! :giggle: The burning time of an electric candle is between $60$ and $80$ hours. It is considered to be continuously uniformly distributed over this period. A Christmas tree with $12$ candles (independent of the burning time), only lights up as long as all candles are working. Determine...

By definition of the vector potential we may write \nabla \times A =B at least in flat space. Does this relation hold in curved space? I am particularly interested if we can still write this in a spatially flat Friedmann-Robertson-Walker background with metric ds^2=dt^2-a^2(dx^2+dy^2+dz^2) and...

I averaged the masses and times (which i took the time given and divided by 10 because in the problem it says you measure the time it takes to complete 10 oscillations) then plugged them directly into the T=(2(pi)((m/k)^1/2) and got the wrong answer. This is really confusing me because I don't...

Hello everyone, I have a hard time to conceptualize the case of a moving black hole. We know from SR that time slows down for moving objects; but time dilation at the event horizon is already equal (tends) to zero. It seems that it can create some sort of conflict for the black hole movement...

I don't know where. to even begin inserting numbers here. I know the Temperature would be -5 for the first T and 36 for T sub zero but I do not know how to solve this. I never had Calculus.

Hi, searching on PF I found this old post Global simultaneity surfaces. I read the book "General Relativity for Mathematicians"- Sachs and Wu section 2.3 - Reference frames (see the page attached). They define a congruence of worldlines as 'proper time synchronizable' iff there exist a...

If gravity is the affect of time dilation because of the distance from the bottom of an object to the top then wouldn’t that mean that gravity doesn’t exist at the quantum level?

Summary:: Averaging (a power of) semimajor axis to position ratio wrt to time - celestial mechanics I evaluated it this far, but i don't know how to change the dt to d theta ... the final solution is supposedly (1-e^2)^-(3/2) . Any help will be appreciated. [Image re-inserted with correct...

My interest is only on Example 6; part c only, see the problem below and the solution from textbook. is the time calculated correctly? I thought we need to use the approach shown below; my thoughts, but of course i may be missing something here, The time taken from points ##A## to ##B## is...

Assume that three boats, ##B_1##, ##B_2## and ##B_3## travel on a lake with a constant magnitude velocity equal to ##v##. ##B_1## always travels towards ##B_2##, which in turn travels towards ##B_3## which ultimately travels towards ##B_1##. Initially, the boats are at points on the water...

I was trying to further look into the fact as to why photons don't experience time and I came across this amazing forum! Planning to indulge in discussions in my free time. I am a software professional by trade. I have to admit, I'm not good at math. I resented math classes in school and...

Is the highest frequency possible the inverse of Planck time? Separate or connected question, what's the highest frequency achievable practically today?

Does time dilation in Special Relativity relate to the Doppler effect? If you move near the speed of light you experience time differently and the sound is stretched. Are these similar phenomenon?

I am just wondering if placing the Earth equidistant from 3 black holes that are spinnng would slow down time on the Earth, due to the time dilation effect. Would that give us more time to live?

Assumptions: There is no "absolute" time, time is all relative. Taking the twins paradox as an example, both twins measure a different proper time when they re-unite due to each twin taking paths of differing lengths through spacetime. Conclusion: Time Travel itself is a completely...

r = 0.25m I = 7.14kgm^2 h = 6.01m Ei = Ef mgh = 1/2mv^2 + 1/2Iw^2 2mgh = mv^2 + I(v^2/r^2) 2(35.8)(9.81)(6.01) = 35.8v^2 + 114.24v^2 v = 5.304 m/s v = d/t 5.304 = 6.01/t t = 1.133 (The correct answer is 2.2673. What did I do wrong?)

I ask this question as a follow-up of an already answered one (about the effect of velocity on time). I'm looking for the effects of SR and GR on a clock's seconds hand. The effect is very tiny though, as you can imagine. Instead of making the size of the clock vary, we can vary c, the speed of...

[Moderator's note: Thread spun off from previous thread due to topic/forum change.] Time dilation sounds really weird, can i assume it has a logical explanation?

Why is time = ct and not t in special relativity? I just started reading the book I was recommended. Maybe I missed it but as stated in the title why is time = ct and not t in special relativity? I understand they want distance/space = time. Just how do they go about doing that mathematically...

assuming initial velocity is 0 and we have the value for acceleration I'm unsure how to still use any of those equations because you must have a time value at least or a final velocity

Everything is in the photo

If I plug the solution into the Schrodinger equation I get $$(i \hbar \partial_t - H)\ket{\psi} = 0$$ Since I know that the zeroth-order expansion is lambda is already a solution I think this is equal to $$(i \hbar \partial_t - H)e^{i\phi} e^{-i\gamma}\ket{\delta n} = 0$$ If now I carry on with...

I recently had a discussion with my brother, about what it means to "move through time". His opinion is, that physicists cannot take this literally. His opinion is, that time is just an expression for change that takes place at different rates for different observers depending on their speed...

With no applied moments, it is asked to prove that a gyroscope Fermi-Walker transports its spin vector ##S_{\alpha} = - \dfrac{1}{2} \epsilon_{\alpha \beta \gamma \delta} J^{\beta \gamma} u^{\delta}##. In a local inertial frame ##u^{\alpha} = (1, \mathbf{0}) = \delta^{\alpha}_0## and...

I have a graph of mean signal (per pixel) vs exposure time (sec) for 8 different dark frames. I am being asked to find the bias in ADUs/pixel and the dark current in ADUs/sec/pixel and I am very confused on how I could get it. I know that the average of all of the mean signals is a rough guide...

I am an amateur in physics and I have a question. How does speed of an object affect time?

I am a little lost on the last step of this problem. I get that we want to know how much time elapses for the capacitor to reach 2/3 of its final charge. That is why 2/3Qf is equal to Qf(1-e^-t/RC). I don't understand how we make the jump to e^-t/Tau is equal to 1/3? and then somehow e^-t/Tau...

A rocket of initial mass m0 is launched vertically upwards from the rest. The rocket burns fuel at the constant rate m', in such a way, that, after t seconds, the mass of the rocket is m0-m't. With a constant buoyancy T, the acceleration becomes equal to a=T/(m0-m't) -g. The atmospheric...

I always find voltage vs time majorly in case of AC current. What about current V time in AC current cases?

Here is something I don't understand which I expect someone here can explain. If one member of an entangled pair goes on a trip at relativistic speeds, there will be two different frames of observation, with two different elapsed times. The time frames can get off-set by years, over a long...

Hello everyone, I wanted to know how speed can dilate time. For example, if there is a star 100 light years away from Earth and I started traveling at light speed, how long would it take for me to get there? I understand that the time differs from the point of reference (ie time from Earth's...

This started from the following post: We have no idea if we will need to keep boosting every few months. The latest information I am aware of is the following: https://www.cnbc.com/2021/10/04/pfizer-covid-vaccine-protection-against-infection-tumbles-to-47percent-study-confirms.html That...