Life Definition and 965 Threads

I have been solving problems from the famous book, "IE Irodov" for couple of days..It was really a terrific job for Mr.Irodov to compile such a huge set of wonderful problems which are very much inspirational. I want to know about Mr. IE Irodov.. I have tried wikipedia.org and google as...

Hi guys I am currently doing some homework for physics and I am having a little bit of difficulty understanding the topic. We are currently studying half life and radioactive decay. We completed a practical involving the rolling of X number of dice and removed all dice that rolled the number 2...

Hello, In science there are so many equilibrium concepts. Pressure, electricity ,concentration... Everything seems to be moving from high to low to reach equilibrium My questions are 1. Why does everything try to reach equilibrium? (Extremes are generally harmful and for survival of...

Homework Statement Given Y=Ae-t/(lambda) find the half life in terms of A and lambdaHomework Equations Y=Ae-t/(lambda) The Attempt at a Solution every time t is a multiple of lambda the relationship then becomes (lambda(n)=A/e^n), i can't figure out how that will relate, i also tried...

1-Half life is the time it takes for half of the nuclei in a sample of radioactive material to decay(Am I right?). Why does the first nucleas that decays,decay first and the one that decays in the end, decay in the end? What's the difference between the two nuclei or what causes this the nuclei...

Homework Statement Find the half life (in hours) of a radioactive substance that is reduced by 5% in 65 hours. Homework Equations The Attempt at a Solution So looking around I find that A=A0e^-kt but I am not really sure how to solve this without having an initial ammount.

Hello, a couple decades ago, an argument was introduced in a notable physics journal of some kind, but I cannot recall the name of this argument, or the journal. I believe it might have been associated with Cambridge, but can't remember. The argument is a logical theory as to why the...

Hi We all know that the hydrocarbons are the corner blocks of life.My question is that what makes them such different?In fact what is the difference between the hydrocarbons and other molcules that gives them such property and what is this property?(I don't know how to tell.I hope you...

I am trying to determine how long a particular battery will last for my application. These numbers are just for an example. Battery stats: 12 V 7 Ah Application 1700 W Power=Current*Voltage 1700W = Current * 12V Current=141.7A Time = 7Ah / 141.7A Time = 0.05 hours Is this...

Today I was at our bookstore grabbing my copy of Goldstein and Jackson for THAT semester of grad school and I decided to pick up some notebooks and paper too. I've come to realize that I've become very picky about paper and pencils! I look back on my undergrad work and I can barely read any of...

A thread\blog of some aerospace stuff I get to do on a day to day basis. These photos are from the AUVSI convention I went to last week. I will be attending a CFD training session\conference in early September out in California. I'll post and pictures from that if I take any, though I doubt it...

If one surveys stars, and their planetary systems, of 4.5 - 5 Byrs old; and then detects terrestrial exoplanet of say 1.5 Earth masses, then one probably still has a magnetosphere - if we are typical (Copernian Principle). And if in habitat zone, then also look for oxygen signature in...

http://news.bbc.co.uk/2/hi/8196807.stm You just can't make this kind of nuttiness up. You just can't...it's funny and sad at the same time. put it on mute, and play your favorite music in the background. They all nod to the beat!

A friend of mine says he has formulated a theory about life which suggests that a decent percentage of cells in a multi-cellular organism doesn't contribute to the organism as a whole and merely exists eating away its resources. Generally speaking, not all cells of type x supposed to do some...

I realize that all encompassing philosophies are frowned upon. However, I see nothing wrong with speculating. Anyway, here goes; 1.Laws of nature do not exist in a Platonic realm, if anything they are descriptions of how things are rather than laws from some transcendental realm that move our...

Ok... I'm 19, in year 11 (not sure of the American equivalent) this is my second time in year 11, I'm the oldest in my school. when i dropped out the first time, i had no drive, no support from anyone, nothing. I got an apprenticeship as a chef, hated it, continued for about 2 years, moved...

Hello I am new to the field. Can someon answere, i cannot find the answere in books. if life 3.8 billion years ago could form in very harsh conditions. then whay cannot it happen again today. whay cannot it have been happening all the time for almost 4 billion years. i have read that all...

Little Tyke [my office cat] came into the office and started making a lot of noise knocking about. Then I realized why: She had brought in a snake that was close to a four-feet long! Cripes! After fighting to keep her away and finally managing to catch the snake by grabbing the tail, as I was...

Just because our Earth has water, why does that mean that life anywhere in the universe needs to have it? I no its most likely it will need it but how do we know? we are one plant of so many life could be out of carbon for all we know.

Hi everyone, Firstly i want to say that I've watched some of the "The Universe" episodes on my computer, and i pretty much have basic knowledge about the cosmos. But there's only one thing in particular that I'm confused: the life of a star. I pretty much know the "core" of it, but i can't...

Since this is about Any book, I decided that General forums would be a good place, feel free to move. What books do you deeply love, have changed you, or believe that every literate person should have? These can be in any language and of any subject. I pose this in hopes of expanding my...

Hi, I am going to be starting physics grad school in August (UT-Austin physics) and was worried about a few websites that I read claiming that a typical physics grad student could expect to work anywhere between 40 and 60 hrs a week on course work in their first year. I am worried because I am...

http://en.wikipedia.org/wiki/The_Secret_Life_of_Plants A very popular book back in the 1970s, have any papers been published that support the claims, and if so, have they been refuted? I remember trying to read it but I couldn't make it all the way through.

This is a strange one, I know. I have background info below. Here is the question: How would one begin to calculate the half life of awareness (the social and political)? What would the equation to calculate that look like? I am a grad student in art and am making work about social...

"Life" after Griffiths EM Hi, I need a textbook on electrodynamics. I have already finished Griffiths electrodynamics, a wonderful book but it does not cover the things I need now from an EM book (i.e. research on photonics). Therefore, I need a book which covers the mathematical methods...

:confused: Hello Could you tell me is there a way of accurately measuring battery life? Basically I have a listening device, it requires 2 x AA batteries, say 2400mAh each (so...4800mAh in total). I am aware you can ‘estimate’ battery life by determining the device’s current consumption...

Here's the short version: Live in New Zealand, been offered an excellent PhD position in the UK. Family won't allow me to leave. I don't want to throw away this opportunity. Long version: My biggest ambition was to get a PhD (physics) from a good university. After 5 years of hard work I've...

Homework Statement A standard light bulb is claimed to have a lifelength of 8000 hours with standard deviation of 800 hours. A newly designed light bulb is claimed to have a life length of 9200 hours with a standard deviation of 600 hours Homework Equations If 36 standard and 36 newly...

Are viruses life?

Long story short, a family member of mine is planning a party for next week and it's causing so many problems. It's going to be about 80-100 people and it's for the various graduates in our family, including meeee! Now of course, the party planning is driving everyone crazy, especially the...

Homework Statement A parent isotope has \tau_\frac{1}{2}=\delta. Its decays through a series of daughters to a final stable isotope. One of the daughter particles has the greatest half life of \tau_\frac{1}{2}=\alpha-- the others are less then a year. At t=0 the parent nuclei has N_0 nuclei...

What level of confidence can be assigned to the statement that all life on Earth has one point of origin - a foundation species? Also, is there any evidence that there may have been other genetic lines, other foundation species and their descendents, that did not survive. I am not asserting...

I'm an Australian , living in Lebanon studying . I as a grade 11 student , Infact, the schools semister is almost finished. So what I'm trying to say that I should pick the domain I have to go through. I do well in math and physics my grades are high , I'm looking forward to be an engineer...

Homework Statement A sample of radioactive nuclei of a certain element can decay only by gamma -emission and beta -emission. If the half-life for gamma -emission is 24 minutes and that for beta -emission is 36 minutes, what's the half-life for the sample? 2. The attempt at a solution...

My "Quarter Life Crisis" :( I have no idea what I want to do. As a kid I attended several summer gifted programs for physics/math/astronomy (believe it or not), and I always thought I knew exactly what I wanted to do: study astrophysics. But I also liked studying everything else. And I do mean...

Homework Statement Ok so I'm doing this practise problem but I have no clue what to do. "A radioactive sample intended for irradiation of a hospital patient is prepared at a nearby lab. The sample has a half-life of 83.61 h. What should it's initial activity be if it's activity is to be...

Half Life / Alpha Decay Question -- No IDea Homework Statement A space rock contains 3.20 g of 147 62 Sm and 0.110 g of 143 60 Nd. 147 62 Sm alpha decays to 143 60 Nd with a half-life of 1.06 1011 yr. If the rock originally contained no , how old is it? Homework Equations ...

Homework Statement http://img5.imageshack.us/img5/8553/halflifei.th.jpg I need to find the half life time of a capacitor and the equation is above.. I know what C is but I don't know R.. is there a way to calculate R in this case? Homework Equations The Attempt at a Solution

Homework Statement If I have a circuit in which the capacitor is the large disk device and for each value of separation=d, calculate the half-life of exponential decay? Homework Equations The Attempt at a Solution What is the formula to do this?

=================================== Life is an ability of matter to manipulate itself. =================================== --- So what do you think? PS: originally I thought it up and wrote it here: https://www.physicsforums.com/showthread.php?t=302477&page=2

I can't feel my life! For some strange reason, I've been thinking a lot about this. Every day that passes and every thing that I do right after that I feel like I have done nothing and accomplished nothing. Its like a feeling of emptiness and this has been going on for the past few months. Its...

The Universe is a pool table, the big bang is the first strike and entropy will result in all the balls in the pocket. This version of the Universe is dictated by fate, everything could be calculated. Life occurs, and although it is more complex without awareness it is still a ball bouncing...

I have completed an experiment to measure the decay rate of an isotope, and I am trying to estimate uncertainties. The half life is 40 seconds, with decays counted over a 15 second period (with many of these 10 second periods for a total of 6 minutes of recordings) However in more detailed...

How long did it take life to form after the oceans had formed?

Is fire a lifeform? Fire moves, grows, consumes, needs oxygen, gives off waste and can "die".

I would like to get a general sense of the life course of a physicists. I'm finishing up my ugrad. studies and moving on to graduate school so I know of the physicist's life course up to this point. I was wondering what happens at graduate school and further on? Specifically: Graduate...

why does it fight so hard to continue it's existence? I'm generalizing all life as a force of it's own. It's one thing to say that life simply evolves, but in a universe of gases, rocks, and lots of space, how does the phenomena of "life" fit into the physics of everything? What is the driving...

Hi i m new here. i 'll get straight to the point. we know that a thermodynamic system always tend to proceed to a higher entropy level then how did 'living organisms' that are highly organized and thus have low entropy emerge from a chaotic system that has very high entropy (here the...

This question might rather be posted in Biology but since the information paradox is usually the subject of black hole physics I thought physicists may be better placed to answer it. The fact that information may be lost in black holes is considered a paradox, information is believed to be...

I'm interested to hear from Grad Students at these schools about anything they wish they had known when they were applying. How competitive/compassionate are the students? How is the weather? Are people happy? Is the town in complete economic distress? Do you like the whole department, or...