Life Definition and 965 Threads

The problem: A radioactive material has a half-life of 50ln2 years. If you add 5 grams per year to the material, how much material will you have after 5 years if you start with 100 grams? What I've done so far: t = ln2/k = 50ln2 k = 1/50 k = .02 A = A0e^-kt N = 100e^(-.02)(5) = 90 grams...

How to determine in a cast aluminum part its consumed fatigue life? Lets imagine I get a cast aluminum part that looks good, but I have no idea for how many km it has been used (automotive). Which kind of non destructive tests or methods could I use to determine the consumed fatigue life, and...

I just finished Peter Singer's book "The Life You Can Save". It deals with practical ethics in approaching the topic of extreme poverty in the world. Peter essentially argues that any money spent on non-essential items and services is morally wrong. That money could be spent helping save the...

What is he earliest time when life could form in the Universe? If it is infinite, there always are very ‘lucky’ regions. We need population III stars, with a very short lifespan. They explode and form clouds with higher metallicity (I assume it is not enough for solid planets?). So we have...

Hi there, As we know, many innovations and designs in science are based off the natural world. I was wondering if it would be possible to create an efficient process of energy transfer similar to how living organisms work, with their use of Enzymes, ATP, etc for relatively efficient energy...

Hi, I have a question something along the lines of Here is a low pass filter, when the resistor = R and the capacitor = C. There is a sinusoidal voltage input source (V1) and a voltage across the capacitor (V2). The transfer function is T(w) = V2/V1. Determine the |T(w)| and arg(T(w)) where...

I am looking at building a pair of third class levers out of materials found at the local hardware store to lift up some 500lb and 1500lb hulls. I have systematically gone through every option available to move these hull pieces out of the mold and I'm left with two: 1) Modify an "off the...

Hello there, new to the forums, but it looked like a good place with knowledgeable folks so I've decided to join! My topic today will be on Jupiters moon Europa. Its just to gauge others ideas on this moon and the chances of it sustaining, or having the potential to sustain life. The...

Why it is said that ARPES measures the lifetime of the injected photo hole? When photons with certain energy promote electrons from the initial state to the final state with kinetic energy then by knowing the photon energy one can simply determine the binding energy of the initial state: Eb =...

If you haven't watched it, can be found here: I watched the second time today and it was absolutely astonishing, didn't quite "get it" the first time. It pretty much explains how life originates. I don't think anything can be added to what the program wanted to convey. I would like to...

Is life most likely to start near greatest statistical mechanical order? For instance, DNA's extended regular structure might relate lowest entropy for its molecular weight. Is biochemical replication the antithesis of randomness? Does the apparent rarity of life in the universe reflect the...

Hi, all! As I'm new to biology and life science, I'm interested in the classification system of life. However it's hard for me to memorize those seemingly Latin words of all kinds of lives. For example, I've absolutely no idea what 'Escherichia' means in Escherichia coli. Do you know...

Just background info. haha sorry so long! If you have the time, please help me. Im 24. All my life I've been taught not to follow my dreams. I've been treated as a nuisance or the special one in the family and have been called stupid as a kid. I've always felt very aware of the intentions...

I am not sure on this, so hope someone can shed some light on this. What type of organism was thought to be among the first on earth? I am not sure if this is the right way to ask this :) Lets say if I wanted to see, or do tests on an organism, and my tests were related to doing tests on...

I honestly don't know what I want for myself, and I'm not getting any younger. I am 25 and I need to devise a plan for my life. Here's a brief history of my life. I graduated from a small engineering school in michigan with a double major in electrical engineering and physics in 2008. Then...

I know someone whose life has been badly affected because his father is a drunkard. That is one the reasons I'm against alcohol because I've seen it with my own eyes how it affects others' lives. There are too many accidents because people drive while drunk. Many other crimes also stem out of...

Questions regarding "Earth life came from Mars" - ? - Thanks Hey guys ans girls, Ok now i am not fully versed in this theory, but the basis is that the life on Earth started from a impact from a piece of mars, that contained organisms, that survived the impact, and started life on earth...

Hello all I was reading an article which claimed science did not have a definition for Life. that statement on face value i think is just plain wrong. I think the author may have ment that it didnt have a definition that everyone will perhaps agree on. I am a computer programmer and my crude...

All the buzz is that NASA has found out something important. http://www.nasa.gov/home/hqnews/2010/nov/HQ_M10-167_Astrobiology.html

As 'unnati D' stated, in the now locked thread, "i believe the concept of a separate life force, existing without d support of an atomic body is worth exploring." This caught my interest, and even if his views may seem misguided and somewhat chaotic, there is an interesting concept worth...

Thought I'd share a thought I had about a year or so ago while I was looking through a Hubble photos book in wonderment at the vast scale of the universe. Suppose our universe is but one in let's say an infinite number of other universes all within a multiverse. And let's say that the...

Homework Statement The half life period of N-13 is 10.1 minute. Its life time is ------- The answer has been given as infinity. Could someone help the formula to arrive at this answer 2. The time taken by the radio active element to reduce 1/e times is ----- The answer has been given as...

1. Suppose that two electronic components in the guidance system for a missile operate independently and that each has a length of life governed by the exponential distribution with mean 1 (with measurements in hundreds of hours). (a) Find the probability density function for the average length...

Let's say that, billions of years into the future, as the universe is beginning to burn out (by spreading itself too thin), humans decide to change the fate. Would it be possible to, say, build millions or billions of machines to go around collecting all the matter in the universe? They could...

Extending Newton's Law to real life. No more "ideal systems"! Homework Statement Newton's Laws in reality, applying all forces 10 pts? A block of mass m is hung on a pulley that is at the end of a table. The pulley connects the hanging block m and another block M that is on the table. The...

A plant for example absorbs minerals and moisture from the soil and radiation from the sun. There is a huge variety of ways that these components can be arranged, but the plant organizes them into very specific structures such as proteins, cells, leaves, stem, roots, etc. There are far more...

I am a sophomore in high-school and have been teaching myself calculus. I understand it all, but I have a hard time seeing where integrals apply to physics and real life. I get the basic stuff, like using integrals to find area on a graph, and how you can use them when talking about velocity and...

HS student taking calc 2 at community college. Currently I will have 2 exams left, and by the way things are going I will probably have a B. My mother has this sick obsessions that I must have a 4.0 GPA in order to get a future scholarship and acceptance at university. She made me re-take...

I am meant to deduce the half life from this table (as attached.) I was under the impression that the half life would occur when the initial activity was halved but my answer of 2.34 minutes (from halving the initial activity of 36506) is wrong. Instead, the answer the textbook got was 1 minute...

Hello, I am interested to know how many readers think that we will find life in our solar system, if so when?. I am confident that we will find basic life forms in a human lifetime. also if anyone thinks that there is more that one intelligent civilisation in our galaxy other than our own...

For example, I just heard that ATMs are possible thanks to the development of elliptic curve theory. Also that internal cell phone antennas are an application of fractal theory. Can you share any other specific examples?

For the past year or so I have been really torn between choosing engineering, physics, or a combination of both. To note, I am a freshmen in college but I need to start forming an idea now because the science and engineering field is really vast. I have a huge passion for understanding the...

I must derive the 1/4th life expression for a first order rxn. ln(\frac{[A]_{\circ}}{[A]_{t}})=kt ln(\frac{[A]\circ}{\frac{1}{4}[A]_{\circ}})=kt_\frac{1}{4} ln(4)=kt_{\frac{1}{4}} do I set t=1/4 ? \frac{ln(4)*4}{k} \frac{5.545}{k} What am I doing wrong here? The answer is allegedly...

Is QM really applicable to everyday life in the macrocosm? If it is, how? And does QM say there are no causes, only effects. So, for example, in th e real world (macrocosm), there is a set of possibilities A, B, and C, and causal factors x, y, and z. However, x is an unknown or hidden...

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...

I want to to know what's the usage of this theory in our life or is there any important application depend on that theory I study it in physics of engineering but i want to to know what's the useful for it?

I give mad props to this man. Read the full story and watch the video: http://goodmenproject.com/2010/10/23/confronting-life/ I applaud this man for taking a stand for his family and others that face similar and difficult situations.

Hello, I have been really interested in nuclear fission in my life, however, have not studied anything solid in the field. I have, however, read a little about it. Basically, I know that in order for fission to take place, a neurton needs to collide with a large, dense nucleus. What I do not...

hi, can we say that life comes essentially from DNA and the resulting proteins?, but it can nly be developed in the right environemental conditions? thank you for your reply

Some people believe that (assuming there is only one Universe) the Universe is so finely-tuned to support life that it is evidence that God exists. If gravity was slightly stronger or weaker, then it wouldn't support the forming of planets and stars as we know it. I've been thinking about...

I know that it begins about 3.8 billion years ago, and hasn't stopped since. But some people said life begins at conception. Is it correct? What is the difference between conception and fertilization?

Hey all, I'm wondering if anyone here can help me try and get things straight in my mind about what I'm going to do next. I'm currently studying Part III (the courses in QFT, Symmetries, Strings etc) and already people are starting to talk about PhD applications, since it seems to be assumed...

Hello guys, I'm a student from Rome, excuse my bad english. I would like to ask you something if I'm not too disturbing.. I'm a student of the first year of University (La Sapienza), and not yet decided which degree to attend: I'm undecided to take physics of computer science. I love physics, I...

If it is claimed that with liquid water, life will probably form, why then would there be only one tree of life on Earth where all life started ? Why is there not a forest of trees, if the conditions are favourable ? Or is it the case there there were possibly more than one and they...

Let me make some definitions. "Personal meaning of life" (PML) is the relationship of oneself current state of existence with oneself desired state of existence. Both change with time thus PML changes with time. "Local meaning of life" (LML) is the relationship of everyone actions taken...

Are there any real life applications of integration for engineers.

Hi, I am not biology student and I want to know this In our body, which organ can live for long time and how long it can live? also which is the organ with shortest life? Nowadays people talk about donating eyes, kidneys after their death. So I got this doubt, that whether these organs are...

What would it be like if a mad scientific genius in real life would cosplay as a fictional mad scientist/wizard? They would probably be the best actor at the convention and get the best cosplay. It would be cheap because they already have lab coats and they are already in character. On...

The question is that the human body contains 0.2% potassium by weight and the natural abundance of 40K is 0.0118%. The half life of 40K is 1.28x10^9 years and I have to calculate the activity in an adult weighing 75 kg. What I tried was to find the decay constant by 0.693/1.12x10^13 hours =...

How can we prove that the mean life time of a radioactive decay is reciprocal to the decay constant?