# What is Lifetime: Definition and 145 Discussions

Lifetime is an American basic cable channel that is part of Lifetime Entertainment Services, a subsidiary of A&E Networks, which is jointly owned by Hearst Communications and The Walt Disney Company. It features programming that is geared toward women or features women in lead roles.
As of January 2016, it is received by 93.8 million households in America.

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1. ### B Virtual particles and Heisenberg

I registered yesterday in this forum with the intention of someone clarifying me how the Heisenberg uncertainty principle can explain the existence of virtual particles. More energy implies less lifetime is only possible if ΔE Δt = h/4Pi, but that's not Heisenberg's principle, the principle is...
2. ### How does relativity affect the detection of atmospheric muons?

TL;DR Summary: I got this question on a quiz for a Coursera course on special relativity, and I'm confused about the answer. I've detailed my thinking below any help on where I went wrong would be greatly appreciated. Question. Muons are unstable fundamental particles. In its own rest frame...
3. ### I Can Topological Protection Extend the Lifetime of a Qubit?

Hi everyone, Besides error correction, what other aspects can we do to prolong a qubit's lifetime?
4. ### Milestones of a human lifetime on a log scale

In another thread the concept of how many seconds in a year came up and it made me think of putting milestones of a human lifetime on a log scale. Units are seconds. Please feel free to amend or change or just make it better. Maybe an actual plot? What strikes me is most of life is in the last...
5. ### I Lifetime and Linewidth: Solving the 2π Factor

I know this is a simple formula, but I got confused online about the ##2\pi## factor. If I have, say ##100## ns lifetime, what is the associated linewidth? Is it ##1/(100 \times 10^{-9} s) = 10## MHz? Or is it ##10/(2\pi) = 1.6## MHz? Thank you!
6. ### Species Age limit tied to 3200 lifetime genetic mutations

It is reported that todays issue of Nature Magazine includes an article reporting a correlation between typical total life time gene mutations and typical life span in a variety of species. I do not subscribe to that magazine and have not it or its abstract on the web. But ... in an article...
7. ### I Experimental average lifetime of particles

My professor said that if I take 10^24 particles, for example, and I observe them for 1 years, I can say that their average lifetime is at least 10^24 years. I am not able to understand why, I though the law of decay is N(t) = N0*e^(-ta), so if after 1 year N(t) = N0, I can say ta ~ 0 , so tau...
8. ### I Particle lifetime (half-life) question

If I have a particle with a average lifetime of 15min, if I take 10 particles confined in a box, after 15 min there will be 5 particles. After 15min 2.5 particles and so on... , but so, at the end there will be the last particle that decades. That particle lived far longer than 15min, but is the...
9. ### I B Meson Lifetime: Exploring B-Tagging & Decay

Hello! I read about a technique called b-tagging in which one can check if a b meson was produced in a collision by looking for a jet which has a secondary vertex within it. The reason is that b mesons are long lived, so that meson would travel a bit before decaying, hence the secondary vertex...
10. ### What is the lifetime of a photon in a medium?

When light travels through a medium like water, it slows down and its speed is no longer equal to c. How does this affect the life time of the photon?
11. ### I Discussion of free neutron lifetime

I'm splitting this off the proton radius thread. The first measurements of the neutron lifetime worked as follows: you get a nuclear reactor as a neutron source and open a port in it to get a beam of neutrons. You count the number of neutrons in the beam and the number of protons (from neutron...
12. ### I Muon lifetime measurement experiment

Hello everybody! I have a question regarding my physics laboratory at the university. I am performing the measure of muon lifetime. The setup is quite standard (coincidence measurement with plastic scintillators). My question is about the time resolution. I have tried to see if the time...
13. ### Lifetime of an oil filter compressor

Hi,I'm doing an internship about mechanical maintenance. I have come to a problem that is a bit over my head. The problem was also discussed by a few process engineers but they did not come with a good solution. So, the oil filter is part of a biogas compressor. The biogas comes from the...
14. ### A Calculating Particle Lifetimes to Unstable Particle Decay

The lifetime of Tritium is about 13 years. The lifetime of positronium is about one-tenth of a nanosecond. Can you point me to some papers or tell me how to calculate the lifetime of an unstable particle? For example, suppose I want to calculate the lifetime of the pion? Or muonium? Etc.
15. ### I Heisenberg - Uncertainty principle - lifetime of a particle

I have seen that the more a particle has a high energy, i.e ##E##, the more its lifetime is short, respecting so the uncertainty principle. But by the definition of this uncertainty principle : ##E\,\Delta t \geq \dfrac{\hbar}{2}##, I can write : ##\Delta t \geq \dfrac{\hbar}{2E}##, then...
16. ### Accelerated lifetime / thermal ageing of power cables

Hi PF Is it possible to perform accelerated lifetime test of thermal ageing on power cables? Let's assume that the cable manufacturer guarantees a service life time of 20 years at max operation temperature 90 [degC]. Is it possible to estimate the expected life time of a cable if I choose to...
17. ### Uncertainty Principle and the lifetime of an excited state

Homework Statement [/B] Estimate the lifetime of the excited state of an atom whose natural emission line width is 3.00 × 10−4 eV. Homework Equations $$\Delta E \Delta t = \frac{1}{2} \times \frac{h}{2\pi}$$ $$\Delta E \Delta t = \frac{h}{2\pi}$$The Attempt at a Solution I think all I...
18. ### How Long Does a Star Live When Converting Hydrogen to Helium?

Homework Statement [/B]Homework EquationsThe Attempt at a Solution I tried T=E/L = 30 X (1.989X10^30) X 0.1 X (3 X 10^8)^2 /(8X10^5 * 3.828X10^26) =1.75 x 10^15 s = 1.33 x 10^9 years . However the answer is 4x10^5 years please help
19. ### How does lifetime of a cyclone affect: precipitation and intensity

When the total lifetime of an extratropical cyclone over the ocean in the Northern Atlantic-region gets longer (within the same season): - Do the total precipitation sums increase? - Does the precipitation intensities increase? - Does the intensity of the cyclone increase? For example what...
20. ### A Sample Test | Component Lifetime

Hi, I'm currently working on a project for which I have to determine the Life-Time of a certain mechanical component within a certain confidence interval. By sampling a small number (let's say n = 10) of these components and measuring the number of hours until failure, I want to determine this...
21. ### I The ever-increasing proton lifetime

I was reading this article discussing how experiments have been able to observe proton decay: https://www.economist.com/news/science-and-technology/21734379-no-guts-no-glory-fundamental-physics-frustrating-physicists It states that after concluding that there has been any evidence of proton...
22. ### The lifetime of the excited states of a hydrogen atom?

How can we differentiate among the lifetimes of the excited states of the hydrogen atom? The states are: 2p, 2s, 3s, 3p
23. U

### Direct Modulation and Photon Lifetime - Laser

Hello, There is a thing I struggle to understand on laser physics. There is a modulation method called direct modulation for semiconductor lasers where by changing the current we modulate the light which is emitted form the laser cavity. There is a picture below It is stated in...
24. ### Does the size of a crystal used for a laser affect lifetime?

I would imagine that it doesn't. I'm really sure how to rationalize this. If emission is a decay process, I don't think the rate constant would change with concentration, and likewise crystal size. Any spectroscopist out there?
25. ### Mass of Hydrogen needed to determine lifetime of proton

Homework Statement The current limit on the proton’s lifetime is determined by observing a large body of water for a long time and noticing that no one of the hydrogen nuclei in H2O have decayed. Assuming that the experiment making this measurement has been going on for 10 years, how many tons...
26. ### How many equations does a physicist write in his lifetime?

How many equations does a physicist write in his/her lifetime on average? Is there any approximate statistics on this? Also how much is this correlated to his/her contribution to physics?
27. ### How many times does an average protein fold?

Does anyone know how many times would an average protein fold in its lifetime? And how long do proteins live on average? Also, another quick question, somewhat related, any knowledge on how many "cascades" of different proteins making a conformational change on different new proteins can there...
28. ### I Could I travel to andromeda in my lifetime?

Hi, this is my first post on here. Let's say I departure from Earth in a spaceship and reach a speed very close to c, as I go faster time would run slower and I would feel as if I was going faster and faster with no speed limit, even though I'm not going faster than c. Because my time is...
29. ### I Relative Mean lifetime of decays

Hi there. I want to compare the mean lifetimes of two particles which decay in a way given by two known reaction formulas, such as ##\rho^0 \rightarrow \pi^+ + \pi^-## and ##\Xi^- \rightarrow \Lambda^0 + \pi^-## In this case it's easy: since the first one corresponds to a first interaction...
30. ### A Minority carrier lifetime determination

I would like to know if it is possible to measure minority carrier lifetime in 300um silicon detectors that have already been cut from the wafers that were fabricated using a set of photo-masks with layers including phosphorus and boron diffusion, metalization of both sides and passivation...
31. ### Time Dilation particle lifetime

Homework Statement An unstable particle with a mean lifetime of 4 microsecond is formed by a high-energy accelerator and projected through a laboratory with a speed of 0.6c a. What is the mean lifetime of the particle as determined by an observer in the labratory b. What is the average...

I was wondering, does the lifetime of a diode depend on how long it takes for all the free P electrons to transfer over to the p holes? In other words, do the electrons that fall into the p holes ever return to the n side?
33. ### Calculating proton decay lifetime correctly?

I'm trying to calculate the SU(5) model's prediction for the lower limit of a proton decay lifetime, for the channel p \rightarrow \pi^{0} e^{+}. I'm following this paper: arXiv:hep-ph/0504276v1 It contains the following equation: As far as I can tell this actually contains a prediction...
34. ### Proton decay lifetime prediction SU(5)?

I'm trying to understand how the SU(5) prediction for the proton decay lifetime of \tau_{p} \sim10^{31} yr has been arrived at. I keep seeing it stated that \tau_{p} \sim \frac{4\pi}{g_{5}^{2}} \frac{M_{X}^{4}}{M_{p}^{5}} where g_{5} is the SU(5) coupling and M_{X,p} are the X boson and proton...
35. ### Acoustic phonon lifetime is larger than optical phonon?

for example, in GaAs, the LA phonon lifetime can be ~850 ns, while LO phonon lifetime is only about 5 ps. Why such huge difference occurs? Thanks!
36. ### Calculation of proton's lifetime

Hi, In a Particle Physics class, our instructor requested me to calculate the life time of proton. There are some sources telling that its life time is ~10^32 years, however there are no basic calculations. There is this article about calculation...
37. ### Lifetime of Universe: Limits & Expansion Explained

I am studying general relativity from Hobson and came across the term 'lifetime' of a closed (k>0) universe, ##t_{lifetime}##. I suppose at late times the curvature dominates and universe starts contracting? Are they simply referring to ##\int_0^{\infty} dt##? If so, would the bottom expression...
38. ### People's lifetime work satisfaction

I always satisfy myself being in the field of science, with the reason, in my opinion, the main or ultimate aim of humans is to understand the "un-understood" matters (problems) of the universe. People can understand repairing dead bodies or getting their body parts repaired by any means of...
39. ### Lifetime of the universe - FRW

Homework Statement [/B] (a) Find the value of A and ##\Omega(\eta)## and plot them. (b) Find ##a_{max}##, lifetime of universe and deceleration parameter ##q_0##. Homework Equations Unsolved problems: Finding lifetime of universe. The Attempt at a Solution Part(a)[/B] FRW equation is...
40. ### Lifetime of rho meson and Kaon

Homework Statement (a) What is a meson? (b) State what these mesons are made up of and explain their quantum numbers and interactions. (c) Find the lifetimes of rho meson and kaon. (d) Find the dominant decay mode and explain why. (e) Why is decay to 2 neutral pions forbidden? (f) Explain how...
41. ### Is one lifetime too little to learn all about the Universe?

I am 30. I am right in the middle of my lifetime, more or less. And I wonder if half a life is enough to grasp Physics by the horns and learn all about nature? I totally love physics, the beauty and mystery that the universe truly is. I actually feel empty without reading or seeing something...
42. ### What is the Mean Lifetime of Muons?

Homework Statement I am doing an experiment where I try to the determine the mean lifetime of muons. I collected enough data and I put it in a histogram (attached file), but I have no idea how to calculate the mean lifetime with this. Homework Equations y(t)=Ne^(-t/τ), where τ is the mean...
43. ### What fraction of adult human cells are not replaced over a normal lifetime ?.

What fraction of adult human cells are not replaced over a normal lifetime ?. see ... http://en.wikipedia.org/wiki/Ship_of_Theseus / [ aka "Trigger's broom" ]. I'm guessing it's a minority : brain and heart only account for about 3% of body weight.[ skeleton is replaced every decade , but...
44. ### Alpha Decay Half-Lives of Notable Light Isotopes: Estimates and Unknowns

What is supposed to be the lifetime of lead against alpha decay? Notable light isotopes that DO undergo alpha decay: Be-8 188 keV 7*10ˇ-16 s Sm-146 2529 keV 103*10ˇ6 y U-235 4679 keV 704*10ˇ6 y U-238 4270 keV 4,47*10ˇ9 y Th-232 4083 keV 14,06*10ˇ9 y Sm-147 2310 keV 106,1*10ˇ9 y Pt-190 3252 keV...

Homework Statement A generation is about one-third of a lifetime. Approximately how many generations have passed since the year 0 AD? Let me first say that this is my first time taking physics and this is all new to me so I appreciate all the help.Homework Equations here is the answer I...
46. ### Is this the correct way to estimate the natural lifetime of an atomic state?

Hi there, I've just been having a little trouble with this short question from a past exam paper... Homework Statement "An atomic state has a dominant decay mode which produces an emission line of wavelength 6 \times 10^{-7} m and natural width 10^{-13} m . Estimate it's natural lifetime...
47. ### What is Decay Width & Its Relation to Particle Lifetime

What is the Decay Width of a particle and how is it related to the particle's lifetime ?
48. ### Methane and CO2 atmospheric lifetime math problem

Homework Statement On a per-molecule basis, methane is 26 times more effective as an infrared absorber than is CO2. Calculate the corresponding ratio on a per-unit-mass basis, and compare it with the 20-year GWP for methane. What's the reason for any discrepncy you find? (CO2 atmospheric...
49. ### Simplified thermonuclear fusion and approximate lifetime of Sun

Homework Statement This is for my intro to General Relativity class, using Hartle's text Gravity: An intro to Einstein's GR. 12.1 "How many protons must combine to make one He nuclei every second to provide the luminosity of the Sun? Estimate how long the Sun could go on at this rate before...
50. ### Why is this correct - particle lifetime probability distribution

Hello, The following problem can be found in van Kampen's "Stochastic Processes in Physics and Chemistry", Third Edition (Exercise I.3.7): The probability distribution of lifetimes in a population is P(t). Show that the conditional probability for individuals of age τ is...