Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience. Time is often referred to as a fourth dimension, along with three spatial dimensions.Time has long been an important subject of study in religion, philosophy, and science, but defining it in a manner applicable to all fields without circularity has consistently eluded scholars.
Nevertheless, diverse fields such as business, industry, sports, the sciences, and the performing arts all incorporate some notion of time into their respective measuring systems.Time in physics is operationally defined as "what a clock reads".The physical nature of time is addressed by general relativity with respect to events in space-time. Examples of events are the collision of two particles, the explosion of a supernova, or the arrival of a rocket ship. Every event can be assigned four numbers representing its time and position (the event's coordinates). However, the numerical values are different for different observers. In general relativity, the question of what time it is now only has meaning relative to a particular observer. Distance and time are intimately related and the time required for light to travel a specific distance is the same for all observers, as first publicly demonstrated by Michelson and Morley. General relativity does not address the nature of time for extremely small intervals where quantum mechanics holds. At this time, there is no generally accepted theory of quantum general relativity. Time is one of the seven fundamental physical quantities in both the International System of Units (SI) and International System of Quantities. The SI base unit of time is the second. Time is used to define other quantities – such as velocity – so defining time in terms of such quantities would result in circularity of definition. An operational definition of time, wherein one says that observing a certain number of repetitions of one or another standard cyclical event (such as the passage of a free-swinging pendulum) constitutes one standard unit such as the second, is highly useful in the conduct of both advanced experiments and everyday affairs of life. To describe observations of an event, a location (position in space) and time are typically noted.
The operational definition of time does not address what the fundamental nature of it is. It does not address why events can happen forward and backward in space, whereas events only happen in the forward progress of time. Investigations into the relationship between space and time led physicists to define the spacetime continuum. General relativity is the primary framework for understanding how spacetime works. Through advances in both theoretical and experimental investigations of space-time, it has been shown that time can be distorted and dilated, particularly at the edges of black holes.
Temporal measurement has occupied scientists and technologists, and was a prime motivation in navigation and astronomy. Periodic events and periodic motion have long served as standards for units of time. Examples include the apparent motion of the sun across the sky, the phases of the moon, the swing of a pendulum, and the beat of a heart. Currently, the international unit of time, the second, is defined by measuring the electronic transition frequency of caesium atoms (see below). Time is also of significant social importance, having economic value ("time is money") as well as personal value, due to an awareness of the limited time in each day and in human life spans.
There are many systems for determining what time it is, including the Global Positioning System, other satellite systems, Coordinated Universal Time and mean solar time. In general, the numbers obtained from different time systems differ from one another.
Homework Statement:: The SI definition of unit of time says the following.
"The second is the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom."
Relevant Equations:: None
I know an...
Hi!
I want to start with saying that I'm not an expert on these type of problems, but I will be gratefull for some calarifications.
I've heard that there's nothing in psysics that says that time travel is impossible. I want to make a case with the time traveling battery. Could be any mass with...
An interesting approach to those eavesdropping devices in your life.
https://arxiv.org/pdf/2112.07076.pdf
ABSTRACT
Automatic speech recognition systems have created exciting possibilities for
applications, however they also enable opportunities for systematic eavesdropping.
We propose a method...
I tried using the equation Q'*t= Q1+Q2. Where Q' is the energy of the reactor aka 200,000 kJ and t is the time. Take Q1 to be (1/2m*2257) and Q2 to be (1/2m*4.184*90). The 90 is the change in temperature for the phase change to occur from liquid water to gas, or boiling. Plugged everything in...
I'm struggling to wrap my head around the twin paradox in special relativity especially when dealing with multiple vectors.
In my thought experiment say I have a set of twins. Both set out in opposite directions and intend to sling shot around two different black holes(luckily equidistant from...
Is it plausible to get the highest grade all the time when your IQ is the highest in your class when you try your hardest?
One answer that I got for this question is "My experience in high school is that if you really have the highest IQ in the class, you’ll get the highest grades without...
Hello,
I try to solve a time dependent problem described by a Hamiltonian of the type $$ \mathcal{H}(t) = H_0 + V \delta(t) .$$
I started by trying to solve the Schrödinger equation with ##H_0 = p^2 / 2m##, but I'm getting a bit stuck.
I would like to know if you know of any books that deal...
I finished my 1st-year physics, took analysis, linear algebra, mathematical logic, classical mechanics, quantum mechanics(I was exempted from intro phy and took some 3rd-year physics courses)
I internal transferred to pure maths. The reason is that the curriculum of the physics programme in our...
I am completely stuck on problem 2.45 of Blennow's book Mathematical Models for Physics and Engineering. @Orodruin It says
"We just stated that the moment of inertia tensor ##I_{ij}## satisfies the relation$${\dot{I}}_{ij}\omega_j=\varepsilon_{ijk}\omega_jI_{kl}\omega_l$$Show that this relation...
Question:
Galileo released a metal ball from rest so that it could roll down a smooth inclined
plane. The time t taken to roll a distance s was measured. He repeated the
experiment, each time recording the time taken to travel a different fraction of the
distance s.
Write an expression for the...
I've started reading Introduction to Quantum Mechanics by Griffiths and I encountered this proof that once normalized the solution of Schrodinger equation will always be normalized in future:
And I am not 100% convinced to this proof. In 1.26 he states that ##\Psi^{*} \frac{\partial...
Taking the variation w.r.t f(x) of the integral over some x domain of F[f(x), f'(x), df(x)/dt], why doesn't df(x)/dt need to be taken a variational derivative and is treated as if it were constant?
Needing Direction
I have sets of number:
week 9 27 turned in 25 good 2 bad = 93% & 7%
week 10 56 turned in 55 good 1 bad = 98% & 2%
week 11 75 turned in 74 good 1 bad = 99% & 1%
week 12 6 turned in 5...
The transition probability -- the probability that a particle which started out in the state ##\psi_a## will be found, at time ##t##, in the state ##\psi_b## -- is
$$P_{a \to b} = \frac{|V_{ab}|}{\hbar^2} \frac{sin^2[(\omega_0 - \omega)t/2]}{(\omega_0 - \omega^2}.$$
(Griffiths, Introduction...
At first, I inputted h(t), of which I solved for, into the mass flow rate formula.
So it looked something like this, m-dot(t) = -(density)*[sqrt(g*(H-(g*d^4*t^2/D^4)]*(pi/4)*d^2
But I don't think that's right? Any thoughts?
I am very interested in quantum mechanics/physics and i keep seeing the Heisenberg uncertainty principle and its making me think about other forms of viewing particles.
We traditionally use Photons to view something (our eyes), or other forms of radiation/particles, but i know that merely...
a tank is filled with water up to its brim a hole was made at the bottom of tank find time taken to empty tank if water flows at rate of 2h kg/s where h is height of liquid column and is equal to 20m radius is equal to h/2
[Moderator's note: moved from a technical forum.]
This the answer key::
im confused because it say "how much energy has been dissipated after 5s". So shouldn't you be looking at the ground after 5 sec.
but apparently the solution look at it before 5 sec, am I missing anything, can someone explain
Daylight saving will be permanent starting in 2023 according to the national news on PBS TV:
https://www.pbs.org/newshour/nation/senate-unanimously-approves-bill-to-make-daylight-saving-time-permanent.
The bipartisan bill, named the Sunshine Protection Act, would ensure Americans would no...
I am going to etch some titanium and need to mix up a 100ml batch of Kroll's reagent ( 92ml distilled water, 6ml nitric acid and 2ml hydrofluoric acid.
Do I add the nitric acid to the water first and then add the hydrofluoric or vice-versa?
hello, i have some diffuculties with this problem, there's the point where the spring is attached to the rod and according to the equation of time period of physical pendulum , h represent the distance from the COM and the pivot point. here the pivot point is at the COM. and i know that it can't...
We think of length and time as the first fundamental quantities and velocity as the first derived quantity but any two determine the third so we would be completely justified in defining velocity as a fundamental quantity and one of length or time as the other, with the remaining being the first...
Hi,
I think this is a simple question, but I just wanted to ask how I could go about showing this in a scientific manner. I will try to use an analogy later on which is, I hope, a simple way to understand what I am doing.
What I am trying to do:
I am trying to investigate whether the...
A nuclear reactor is built to fuse two hydrogen atoms that are already ionized to protons. However, the electric field of the protons are becoming a significant obstacle. If the reaction was to be defined as H2--> 2H++2e-, if the mass of a proton is mp, the radius of a proton r the charge of an...
Hi,
It's not a homework but still thought to post it here as advised in the past.
A rocket is going to leave Earth's surface and it is decided that a data pulse encoding emission time of pulse will be sent every second from Earth station to the rocket, and the rocket would do the same.
The...
Given a wavefunction ψ(x, 0) of a free particle at initial time t=0, I need to write the general expression of the function at time t. I used a Fourier transform of ψ(x, t) in terms of ψ(p, t), but, i don't understand how to use green's functions and the time dependent schrodinger equation to...
Vertical components:
dy = 0m
ay = 9.8m/s^2 [down]
t = 1.34s
V1y = required
V2y = 0
i first tried to find V1y
dy =vi t + 1/2 a t^2
and got V1y = -6.566
then i solved for time of flight
dy =vi t + 1/2 a t^2
0 = -6.566t + 4/9t^2
and for 1.34 seconds
does this mean the time of flight is the...
As I understand it, photons are subject to the same time and space distortions under SR as anything else, which is why they don't perceive time or space, since they travel at the speed of light. To an outside observer, then, they should appear stationary, immobile at their moment of creation...
This is still a confusing concept for me. The Lorentz transformation for proper time is expressed as tau = (1-v sq/c sq)^1/2 x coordinate time. Now we are told that tau is an invariant quantity with respect to all moving reference frames. So how can tau be invariant if its value depends on v...
Been studying Special Relativity in Uni. and I've noticed that all examples of relativistic motion provided are motions only along a single axis, like the one below:
The particle's Reference Frame is moving only along the X axis in the example above.
In this case the Lorentz Transformation for...
Question about time dilation. What if two clocks used the same reference frame? For instance, 2 countdown clocks using a particular pulsar as a measure of time. One stays here, the other is sent 100 million miles away at a very high velocity. Would they still reach 000 at the same time?
Here's my list of variables and things to account for:
m=100kg
Wnc=5000J
Wfriction=-500J
-Kinetic energy will be doubled (though I don't know how that plays into it exactly)
-I don't think there's any PE because it's on level ground
My idea of what the equation might be:
Wnc +1/2mv^2initial =...
A week ago I accepted to review a paper for a top journal. I was contacted because I've published several papers on the same semi-obscure topic in the last two years. I accepted because the abstract was interesting and thought provoking.
However, after having access to the full paper I...
Ion traps are very complex, but one of my Physics Olympiad textbooks presents a simplified model of a resonating charged particle in an ion trap
A tuned circuit consists of an inductor and a parallel plate capacitor (capacitance C and plate separation d). It has a resonating frequency ##\nu...
I recently trying to learn General Relativity by first scraping the surface on ScienceClic's general relativity playlist, and then I stumbled upon a video where it said that we actually move through spacetime on a constant speed of c, and then I remember about time dilation because how speed on...
Water heater has the effect 2kW and is filled with 2kg water, with a heat capacity of 4,18Kj. The water needs to be warmed from 300K to 400K. How much time does it take for it to warm up?
I've tried to solve this, but it seems that i need to know the heat capacity of the water heater, which i...
As of today, there are plenty of time machine mathematical models based on general relativity theory (warp drives, wormholes), but few ones based on quantum physics. However, back in 2010, Seth Lloyd wrote: "quantum mechanics supports a variety of counter-intuitive phenomena which might allow...
F.B.D Of first block
(I have shown only the horizontal Forces)
f1(max) = μ (1kg)(g) = 0.5 * 10 = 5N
F.B.D Of the second Block
f2(max) = μ (3kg)(g) = 15N
Now the string will become taut and the tension will start acting when f = t = 5N
But for 0<f<5N there will be no motion between the 1 kg...
Before starting, I will leave the link to the article I am talking about here: http://www.msc.univ-paris-diderot.fr/~phyexp/uploads/LaimantParesseux/aimant2.pdf
I am conducting a similar experiment to the one discussed in the paper above. Basically, I am rolling a neodium supermagnet down a...
My attempt :
##\frac{\vec Ft^2}{2}=m\vec s##
##s=\frac{Ft^2}{2m}##
##P=\frac{W}{t}##
##k=\frac{\vec F\cdot \vec s}{t}##
##k=\frac{F^2t^2}{2mt}##
##k=\frac{F^2t}{2m}##
##F=\sqrt{\frac{2mk}{t}}##
But there was an option which was ##2\sqrt{\frac{mk}{t}}##. And my assumption was that it was...