Age Definition and 571 Threads

It seems if one could travel at the speed of light, they would never age. Time stops. So if someone wants to slow down the aging process, say compared to their friends, they need to take a trip as close to the speed of light as possible. Contrary to that, many young children can't wait to get...

Is it coincidental that the Hubble Sphere, in light years, is approximately the age of the universe computed as 1/Ho (13.7 billion years)? If the recession speed exceeds the speed of light, the photon would never reach the observer, this is why there exists a horizon of the visible Universe...

Hi all, Can someone tell me how old are the atoms my body is made off? In other words, how old am I really? THANKS

I may be simplifying but if the universe is spacetime and time is local how can you define a time elapsed from the big bang for the whole Universe?

http://scienceblogs.com/principles/2010/02/physics_quiz_accelerated_twins.php The answer, they claim, is that Alice ages more than Bob. But say this were true, it would also mean that of two synchronized clocks placed on opposite sides of the earth, one at sunrise, and the other at sunset...

Recently I saw this in the news...any thoughts on this? jhd as joesmith

I've read that in the far distant future that because of the expansion of space, protons and other particles will grow to huge sizes compared with today and some may grow to be almost equivalent to the current size of the universe. But will the speed of light increase as well? If these particles...

with we travel in space shuttle with speed closer to that of light,when we come back to Earth after few years there is significant difference between our age and people of that of earth.now how does that happen does the cells of human body mutate with the speed different than that of cells on...

I was wondering if, immediately following the expansion of the universe there might have been objects of matter with immense gravity like that of a black hole. For the observer on such an object that still exists, what would the age of the universe be? You could substitue this with an object...

The ship is twice as old as the boiler was when the ship was as old as the boiler is. What is the ratio of their ages? I do believe I have solved this (without Googling) and have uploaded my answer online with a timestamp of 10:35PM 4/27/2011 (i.e. before I posted this). Let me know...

Hi, i want to ask about the basic explanation of twin paradox. In the explanation it says one twin has to accelarate to come back and the symmetry is broken and so one twin is older than other. Could you explain this symmetry and aging relation?

I wasn't sure whether or not to post this in the Astronomy section but as this is homework, I decided to post it here. Homework Statement Suppose the Universe was much younger, eg 10,000 yrs old. Find the Hubble constant for such a Universe. Compare with the currently accepted value. What...

Hey all, I'm a non-traditional student. I won't even begin graduate school until I'm 32 or 33. As of now, my plan is to become a mathematics professor (yes i know the slim statistics and no i don't want to dwell on that), and I'm wondering, will being ~10 years older than my peers affect...

whenever i think about the age of the universe compared to the size of it i get frustrated. how can a 50 billion+ light year universe fit in 14 billion years of space? my younger self said nothing can go faster than light so the universe couldn't have grown more light years in size than years...

Hello, I am very interested in the fields of physics. I want to study physics after I complete high school. I am currently fourteen years old and in the 8th grade. I have been reading books on many famous physicists, like Stephen Hawking and Richard Feynman. I soon realized that physics...

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I am not a cosmologist so do not understand how light from the most distant galaxies could take 13.7 billion years to reach us when 13.7 billion years ago the universe was much smaller.

Homework Statement a living speciman in equilibrium with the atmosphere contains one atom of 14C half life of 5730 for every 7.7x10^11 stable carbon atoms. An archaelogical sample of wood cellulose C12H22O11 contains 21.0mg of carbon. when the sample is placed inside a sheilded beta...

Moon rocks containing uranium 238, decays to lead with a half life of 4.5 billion yrs. The lunar rock sample you're invistigating contains half of the original uranium 238. How old is the rock? How would I go about solving this? What formula should I use?

If the universe is 13.7 billion years old, then how can the observable universe reach out 46 billion light years, given that nothing can travel faster than light? Is it to do with the expansion of space, which doesn't abide by relativity laws?

Do all observers agree on the age of our Universe? If not is there some measure they do agree on? Thanks for any help!

1. Construct a program that will ask the user the current date and his/her birthday and display the number of days they have been alive. You can ignore leap years.The Attempt at a Solution I have little experience in MATLAB or programming in general, but a little help to get me started would be...

Why does t=1/H (hubble constant) indicate that that is the age of the universe?

Some years ago i was walking along a beach in France and i found this fossil... Does somebody know the plant, the rock and the age of the fossil? or how can i found the plant that was fossiled or the age? THANKS!(sorry for my english) ABOVE YOU CAN SEE THE PICTURES CLEARLY...

Nuclear decay and the "age" of atoms. All atomic nuclei heavier than hydrogen were created in stars and would therefore seem to have different ages relative to some specific spacetime reference. Nuclear decay wrt a single atom is taken to be a temporally random event, but is it plausible to...

The Incredible Flying Nonagenarian http://www.nytimes.com/2010/11/28/magazine/28athletes-t.html Exercise (and diet) is important to good health, especially later in life.

NYTimes.com, By DENNIS OVERBYE Published: November 17, 2010 "Allan Sandage, Astronomer, Dies at 84; Charted Cosmos’s Age and Expansion: Allan R. Sandage, who spent his life measuring the universe, becoming the most influential astronomer of his generation, died Saturday at his home in...

Homework Statement seashell HAVE 90% of 14-C as a livining shell of the same size half life is 5570 years, how old is it in years how many yrs did it take for 14-C to diminish from its initial value to 99% of that? Homework Equations The Attempt at a Solution for the first part...

So, supposedly the age of the universe is about 14 billion years. But the only reason we believe that is because we can only see something 14 billions years away. Do we just assume that just because we can't see past the 14 billion mark, there's nothing there? And by that assumption, shouldn't...

Does anyone know if there is an understood correlation between the amount of dark matter we suspect in a galaxy and the age of the galaxy? Basically, I am wondering if older galaxies tend to have more dark matter. But I need references to information on this, not just opinions :) Thanks.

http://news.yahoo.com/s/ap/20100928/ap_on_re_as/as_nkorea_succession" . How embarrassing!

Homework Statement The half-life of radioactive carbon 14 is 5700 years. After a plant or animal dies, the level of carbon 14 decreases as the adioactive carbon disintegrates. The decay of radioactive material is given by the relationship A = A0e^(-kt), where A0 is the initial amount of...

Homework Statement Alpha Centauri is about 4 light years from the Earth. If you were to travel to Alpha Centauri and back at the speed of the electron that you calculated in question A (0.780c), how much would you age compared to an observer on Earth? Homework Equations There equations...

I thought i understood a light year as a measure of distance.But i keep running into articles that say something like ...around Galaxy NCG 4921 there are a cluster of galaxies estimated to be 13+ billion years old at a distance of 320 light years from earth.How do you get that when you are...

Do photons remain stationary in the fourth dimension? Do photons age? Thanks! :)

Hello, I was pondering the age of the universe and reading about how it was calculated, but then I began questioning something. Two scenarios, BIG IF. (I know, it's a big IF. I'm sure I'll get a lot of comments about how it's not possible, or improbable. I get it. but...) IF: -We...

I don't know if this belongs in this part of the forum but I'll ask here first. (It might delve into the different subjects of biology and etc.) Whenever I hear people speak about something that happened to them in the past, I'll generally hear them linking the memory to when they were a...

It is told that the universe is 13.4 billion years old according to present estimates. But as duration itself is a relative quantity what exactly is meant by this statement? Which frame of reference are we talking about when considering this figure and why?

How do you integrate 2exp(1-x).dx? The expression describes the cumulative number of cells as a function of cell age (0 newborn, 1 at division) in an exponentially growing culture. Thanks for any help. Dave

A paper written by Authors: Rong-Jia Yang, Shuang Nan Zhang, published in Mon. Not. R. Astron. Soc. 000, 1–7 (2009) and modified on today's Physics ArXiv asks a question we have looked at before on PF, "Is there an age problem in the early universe of the \LambdaCDM model?" At high red shift...

I am 40. I finished physics (BS) 15 years ago. But I din't work as a physicist. Can I make phyics career or PHD on physics now?

I've been looking at some of the more prestigious graduate programs in physics and I've noticed in photographs that all of the grad students look very young. On the Princeton website, I couldn't spot one that looked over 25. Is it fair to say that more prestigious institutions tend to avoid...

Hey folks I'm totally knew to this forums but i assure you I'm a science junky (especially Physics) I figured i post my first question here as it seemed pretty general so I'll give it a go I've heard many statements about the universe being finite, in fact, it seems to be regarded as truth...

Age of Universe inaccurate?? Hi. i have a question that could already been nullified. Reading about the CMB it occurred to me that normal light is around 370 - 770 nm in wavelength and a microwave could be upto 30cm long.. That means light has been expanded a million fold?? (not sure) since...

if time has no meaning for a photon, do you think its correct to say that from its point of view that age of the universe is 0 seconds?

Hallo, maybe I should not be writing here but I need more opinions on prescribing statins to a child at age 5. We have a family heredity of high cholesterol level (my mother, both my sisters an myself and now my son). My son was firts tested at age three when I told the pediatrician that we have...

Hello, I am curious about the quantum suicide theory and what it may mean for the individual in his/her own time branches. The quantum suicide theory states that there is a gun powered by some sort of quantum particle generator that is programed to fire when the particle is there and not...

He and Glen Rebka first observed the gravitational redshift of light in a terrestrial laboratory. He was also involved in the discovery of nuclear magnetic resonance. Amazingly, although he was on the Harvard faculty for many years and even served as physics department chairman, he never earned...

Homework Statement Hi! I'm stuck on this one too. "A rock contains the radioactive isotope Rb-87. A piece of this rock contained 2,05*10^20 Rb-87 atoms and 8,25*10^20 decay products per kg. The half-life of Rb-87 is 47*10^9 years. How old is the rock?" Homework Equations...

Homework Statement Two twins, Bill and Ben are 30.0 years old and they leave Earth for a distant planet 12.0 light years away. The twins depart at the same time on Earth, and travel in different space ships. Bill travels at 0.93c, while Ben travels at 0.70c. What is the difference between...