Age Definition and 590 Threads

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...

The death song of the Ood has carried the old Doctor away, but the new Doctor arrives in America April 17th. http://www.bbcamerica.com/shows/doctor-who/index.jsp?utm_source=google&utm_medium=cpc&utm_term=dr_who&utm_content=text&utm_campaign=doctor_who_premiere_2010 I do believe this is the...

Hi, Let's say that you had the following information (age with errors, U-B, B-V, V) for 100 star clusters, what would you do with it? What can it be useful for? Just wondering...

I was watching a video on the scale of the observable universe. At the end, it shows the famous WMAP imagery and at the bottom it reads that the age of the observable universe is about 13.5 billion years old, but that due to the expansion of space the actual age is closer to 93 billion years. I...

Hi all, Hoping you can help with this problem! Homework Statement For a flat universe, show that t_{0}=2/3 (H_{0})^{-1} ? Seems like a simple problem I just don't really know where to start. Homework Equations Hubble's law v= H_{0}r and then t= 1/H_{0} The Attempt at a...

Hi I want ask how to know the age of Earth with superparamagnetism ( magnetic rock) ? Thanks

Hello. This is one of my coursework questions I was wondering if I could get some insight here.. here is the question: The size of the Universe if conveniently parameterized by a scale factor, a(t), which simply describes how big the Universe is at other times relative to its present size...

Hello! i was just wondering if anyone could help me with this, The rubidium isotope 87-Rb is a beta emitter with a half life of 4.9 x 10^10 yr that decays into 87-Sr. It is used to determine the age of rocks and fossils. Certain rocks contain a ratio of 87-Sr to 87Rb of 0.0100. Assuming there...

HI Can someone give a good explanation of how we can infer an age of the universe from the CMBR. I was thinking in principle you could get an estimate from determining the rate at which the CMBR is changing, but experimentally that would seem to difficult to observe. Also i guess that assumes...

How long ago was the last ice age? Does an ice age pose any threats to species on Earth? If there were a 2nd ice age, would humanity survive it?

Let me know if there are any errors or holes in my logic, facts, or assumptions. I was thinking in regards to time being relative to the observer and the resulting impossibility of an objective measure of time: In determining the age of the universe, our current estimation is about 13.2...

Assuming it has only been recently discovered that the expanding universe is expanding at an accelerated rate, and assuming the calculation of the age and distances to galaxies has been based on the old rate of expansion. Does that not affect the estimate of how old the universe is? Does that...

Amazingly 50,000 years of pollen analysis in the Amazonian pan sediments has revealed that the rainforest was consistent throughtout the glacial period without extensive savannah-isation due to the hypothesis of increased aridity. How did the Amazon stay supplied with so much rainfall during an...

Not only grassland animals grew in size to mega proportions, but there's also evidence to suggest that some jungle animals did as well. The grasslands can perhaps be explained by increased aridity, but that alone can't explain twice size pleistocene tree-top monkeys, can it...

Special relativity tells us that twins age differently if after birth they part, follow different paths through spacetime and then reunite. The twin who follows the longest worldline ages least. At least this is how I imagine the twin paradox, which I thought I understood. Here's a silly...

Two friends Andy and Cal form a team together. Andy is as old as Cal will be when Andy is twice as old as Cal was when Andy was half as old as the sum of their current ages. Cal is as old as Andy was when Cal was half as old as he will become in ten years. Determine the respective current...

How probable is a large-scale war in the next 20 years? Are there any significant growing tensions between powerful countries? Would a violent war be constructive to anyone? I remember this quote: "I know not with what weapons World War III will be fought, but World War IV will be fought...

Very cool! We just got a new computer that is dedicated almost entirely to the TV. Between Netflix, which charges what I consider to be a nominal fee if one utilizes all of the perks, the ever-growing number of sources and databases that provide free television programs, movies, and...

To those of you in physics, what age did you obtain ph.d. ? And to those of you who didn't get ph.d. yet, what age do you anticipate in getting it?

How has it been calculated that the universe really began 13.7 billion years ago with the big bang? Carbon dating or some other method? How exactly did they arrive at this conclusion ?

Hi all, This is my first endeavor into the astronomy forum. I have a question, regarding three things I think I know about the universe. 1. the universe started as a singularity. 2. it has expanded to 78 billion light-years across. 3. it did that in only 13.7 billion years. How did...

Hi All, how is the age of universe calculated ? i read a few articles/wiki etc and its estimated to be roughly 13.7 billion yrs old. Have we considered the time dilation effect here ? cause we are measuring the electro magnetic radiation traveling in an expanding universe and in an...

Is it correct that the age of a star, such as the sun, is calculated by measuring the amount of helium made from fusion? If so, how do we know if that the star didn't form from a cloud that already had helium in it?

When did plate tectonics start? http://en.wikipedia.org/wiki/Plate_tectonics"

How exactly to calculate the age difference in "Twin paradox" In so much of the text I have seen the "twin paradox" is resolved by simply showing how the condition is asymmetrical, they make no calculation on how this asymmetry results in age difference. I have seen some claiming that its...

Hello. I want to study Physics. I'm 14(15 next month). I know Newton's Laws of Motion. I want to know in what order should I study Physics. I know 9th grade Algebra. No books please.

What's your Age? How about the Age of Consciousness? When we respectfully acknowledge all sentient life. When artificial life and physics in general become indistinguishable from biology. When all of our thoughts are self-determined. When science allows awareness beyond immediate...

My career aspiration is to teach Mathematics at a post-secondary level. Whether it be Community College, a private university, or state university. Which would be better to go after? A B.A. or a B.S. in Mathematics? I understand that I would need at least a Master's to teach at Community...

In "Elizabeth 2: The Golden Age", what is the name of that half cape they wear?

Homework Statement Scott Carpenter orbited the Earth 22 times in 1962. Assuming he was 160 km above Earth in a circular orbit, determine the time difference between someone on the Earth and Carpenter for the 22 orbits. Homework Equations L = Lp(1 - v^2/c^2)^.5 delta t = t /(1...

I'm trying to find a source for the HPV demographics by age. The best I found was: The Value of Monitoring Human Papillomavirus DNA Results for Papanicolaou Tests Diagnosed as Atypical Squamous Cells of Undetermined Significance: A College of American Pathologists Q-Probes Study of 68...

This is pretty fascinating.. Article: http://abcnews.go.com/print?id=7880954 Brooke rides in a stroller while her mom shops for clothes in the infant sections of department stores near their home in a Baltimore suburb. That Brooke is in her mid-teens is so mind-boggling that if another mother...

This story inspired this thread: http://www.redicecreations.com/article.php?id=6906 If you ask me, the media is misrepresenting this case which is really a poor, unhealthy child with an extraordinary development disorder... they think that no development means no aging, but i'd be...

Following different lines of reasoning (most likely all faulty) - I can convince myself that the current estimate(s) of the Hubble age may be off by a factor or 2 (more or less) depending upon the physiology asssumed for space and the model used to describe the expansion rate - specifically: If...

With normal I mean the age when most engineers receive their degree. I have a feeling that it is quite late compared to most other countries?

Difference in age ?? NOTE : THIS IS JUST AN IMAGINATION ! Imagine that 2 babies are born on the same day & time (with names A & B)..A is allowed to live on Earth .But B is taken in a rocket and is sent to space .(this rocket can travel in the speed of light!) A is now 10 years old ...on...

Hello. I was recently reading up on the furthest start found so far to have been dated to approximately 13.7 billion years ago if I remember correctly. I'm curious though, how is the "age" of this light approximated? Photons themselves are radiation right soo...? Thanks in advance.

Okay, first off I'm not starting a debate here But I am debating with a friend, and I wanted to know if there is any critical analysis done on the various papers and books produced by this group (Radioisotopes and the Age of the Earth). In my quick searches I've mainly found blogs and...

I'm always perplexed by the numbers I see on estimates of the age of the universe and the age of our solar system. Somehow, I don't see it adding up. Here's my logic, plese point out the flaw: 1- Current estimate of the age of the universe : 13.73 billion years give or take. (when I was in...

Something that always got me thinking about is time is relative to the speed of the object (time dilation) how can we determine age of universe. Here is an example of what I'm thinking. When the big bang happened, imagine if certain parts of the big bang it got flung at different speeds...

Hi New on here and wanted to show my stupidity by asking a question that is perplexing me and hoped you could help Maybe someone could point out that some of my facts are wrong but here goes The universe is supposed to be 76 billion light years across The universe is supposed to be...