Life Definition and 1000 Threads

Hello Folks, I have an interesting question (I think)... how far back in the history of universe would you have to go before any form of life existed? Thanks. CJ

Homework Statement Electric motor in put power rating is 17.5kw Voltage is 48V Battery is 7.5kw/h Average W needed to maintain motor per sec is 1446.7W Homework Equations Motor: W=I*V > I = 364.58Amps The Attempt at a Solution My attempt: If 1kw = 3.6 x10^6J > 7.5 * 3.6 x 10^6 =...

Yes, I know that it should be found and hunted (harvested?) first. ;) Let's take assumption that's a carbon based life form using water as solvent. Are the aminoacids that we use the only feasible and convergent evolution would cause that they would have the same? What would be a reaction...

How can a bride get all money of her husband in your culture ? Is it possiblethat he should hide his bank account or maybe he creates 2 accounts, one is let known and the other is not; after each payment he has got from work, he withdraws half then deposits it into the other account. Being a...

Hello everyone, I recently found this site PhysicsForums and hope I can find some help from it. I've written a 6600 word essay on everything I learn from the Universe using youtube. I did it just for my own knowledge, how and why things work the way they do. I'm in grade 11 and almost going into...

I'm starting my PhD a few weeks from now. I'm just wondering if I will likely have any free time to enjoy myself, or whether the next 3 years are going to be a long, hard battle with hardly enough time to pause for breath?

Homework Statement This is the equation y = y0e-kt Homework Equations b) Show using your expression for λ that if at time t1 the amount is y1, then at time t1 + λ it will be y1/2, no matter what t1 is. The Attempt at a Solution y1=y0ekt1 that part I got. Then the answer key...

From what I've read all processes of a thermodynamic system are irreversible because some energy will be lost to the surroundings but I don't understand why that can't be reversed by getting the surroundings to put that energy back into the system. Let's say I have a gas canister with a piston...

Wouldn't that suggest that life is a rare event in the universe? If it were common, shouldn't we expect it to have developed more than once on Earth?

Hey, not sure if this is the correct forum but it seems physics will ultimately bring down the telescope. Why can't we leave the Hubble in space until it doesn't work anymore? It doesn't have any space crew to kill, it would break up on re-entree harming no-one and would continue to inspire our...

Hi all, If we find some fossils there, will we be able to tell if it's DNA-based? Similarly if we find fossils (or even current life) on Europa what is it likely to be based on? I'm very curious if extraterrestrial life is like what we have here on Earth or not. It seems clear that...

I am currently trying to use calculus to solve a problem that I have been trying to determine for some time. I will present what I have determined so far. The Problem: A hero in a popular video game (In this case LoL) regenerates 7.5% of his attack damage as mana every time he damages a...

I don't know how to solve the questions that my lecturer gave me. I not understand about probability of half life. Can anyone explain to me and help me solve the questions as well? My lecturer ask us to prove the probability as shown in the picture.

Here are what I might call the ages of my life: Year 0-3: Unremembered. Years 3-10: Awakened. Years 10-13: Rebellious. Years 13-19: Sublime. Years 19-25: Disturbed. Years 25-35: Idyllic. Years 35-41: Panicked. Years 41-52: Romantic. (Notice the alternations.) And yours?

Even though life on Earth spans such diverse creatures from bacteria to humans, at its core, all life on Earth is pretty much the same. Life as we know it uses the same four bases to store information in DNA, the same 20 amino acids to build proteins, and the same genetic code to convert DNA...

Hi All, I'm a newbie here and I don't know enough about physics to answer my question, so I will submit what I think I know to be true, then pose some questions, therefore please pardon any allowable mistakes. 1) Time is immaterial for my purposes in this posting, at least in a...

Nickel-Iron batteries are making a comeback in the renewable-energy industry. My personal interest happens to be for wind generator/solar power energy storage and also for a pendulum gear-driven clock design that I am working on where I need a minute amount of stored power to operate a small...

Hi, I've been thinking (a bit late in the course of things) that I have been making bad decisions... Bad decision 1# Choosing Physics for my degree 2# Going for teaching (quit after two months) 3# Currently on course for an MRes leading to a Phd...

So I have a power supply, 9-12 V output and I have a component that takes 9-12 V. When I plug the power supply into the wall and measure the potential across it's leads, I get 16V. I put a resistor across the leads and measure the diff across the resistor. Again, 16V. I look at several...

Is there a relationship between the inverse fine-structure constant (alpha) and the life span of elementary particles?

Yeah is there any correlation between being single for the rest of your life and very successful in Math/physics?

Do You Use The "F" Word In Real Life? A recent post by Evo warning about bad language in an article: I think an English teacher I had pinpointed the biggest problem with the "F" word: those who use it tend to extend it into a multipurpose word that fills all conversational needs. It becomes...

Hello PF. I will give you my thoughts about the chance of there being life in the universe and I would like you too write what you think and maybe come with arguments against me. I am not very pro in any way at all so I may be incorrect in some things and if I am I would be happy if you can...

I just bought lunch at Quizno's. On top of a cabinet, between the cash register and the fountaion drink machine, in essentially the most prominent place in the establishment is this little framed 3" square metal plaque. It's like a little boiler plate off a machine - the lettering is stamped...

How do life and all processes linked to life go along with the second law of thermodynamics? If living creatures decrease their entropy because they are open systems and in a state of non-equilibrium with the environment, in general does the total entropy increase? (for example, if we have two...

Okay, If Uranium's half life is 4.5 billion years, why does it become waste at a reactor before it decays 4.5 billion years later... Forgive me if my question is badly worded or really stupid; I am a high-school student who has just finished the topic of "Nuclear Energy" in my physics class...

Whats the work life of an experimental physicist like? Hours? Pay? Activities and duties? etc. etc.

Homework Statement I'm not in school and although I took plenty of physics back in high school, I've forgotten most of what I need for this. I'm not asking for anyone to do the work for me, but it's been so long I don't even know which formula I should use to solve the problem. I can do the...

Here at National Taiwan University, there is a beautiful lake called the Drunken Moon Lake which is basically right next to my office at Astro-Math Building. I have been observing a family of Common Moorhen for months. The first time I noticed them was probably back in March, when the pair had...

Homework Statement 5 people of ages (30M, 32M, 37F, 40M, 42F) enter into a life insurance contract where the one that outlives the others, receives a one time benefit of $1M, at the time of the penultimate death. What are the fair premiums (different), for each policy member?Homework Equations...

Homework Statement I have some data for "Activity(Bq * 10^4)" and "time". I have already found the half life and everything but I can't seem to see any sources of error in the data Homework Equations I need sources of error. The Attempt at a Solution I said, the half life matches the...

Hey guys! Long time since my last(first¿?) post. A lot has happened over the past few months; I think I need a little catharsis. I just finished my first semester as a physics major and today arrived home (I don’t study in my hometown). Here in Colombia there is a national exam that every...

Does anyone know how many cycles (extend / retract) that a hydraulic cylinder should be able to do before needing repair? The specifics for the cylinder are that there is minimal (almost none) low frequency and low amplitude pulsing of pressure. The cylinder will cycle once every 5 minutes...

Homework Statement half life of carbon 14 is 5730 years. living matter produces 15.3 disintegrations per min per gram of carbon it contains. A 1g sample of a plant from an excavation shows 7 disintegrations per min from carbon-14. how long did the plant die? Homework Equations k = 1/ t...

Hi, Adiabatic, iosbaric and isochoric processes are good approximations for a lot of thermodynamic phenomena in every day life. But the conditions for a process to be isothermal are so artificial that i have grave difficulties to fudge a story. Are there any examples of thermal...

Did you dreamed of future (like place you want to live, work you want to do, partner you want to live with) 10,20,30,40,50, ... years ago and how close you got your near you dreams? I would need to work on finding if I ever dreamed something that I have now. So far, my life have been quite...

I am currently taking calculus, and will be done with differential equations by the time I graduate high school, maybe by junior year. I was wondering what comes after differential equations, because up to differential equations there was a series of maths that you were supposed to take...

So I was thinking about numbers like pi. If you were to measure the area or circumference of a sphere in real life, you would get a never ending decimal. How can this exist in real life? How can an actual physical object have a circumference that is an irrational number?

My life hasn't exactly gone as planned... I graduated in 2008 with a double major in electrical engineering and physics and had always wanted to go to graduate school in electrical engineering and get a PhD so I could one day become a professor. Well, I got accepted to a good grad school and...

I have think I might have a feeble grasp on the idea that simultaneity of events at different points of space depends on the reference frame. However I was having a conversation with my friend and we were trying to figure out if there would be a reference frame where our whole life happened...

Can you convert Half Life into Becquerels? How?

what makes half life(T) of radiation independent of the quantity of radioactive substance? why is it constant whatever the amount of the radioactive substance is?

I've understood the basic idea of why a gyroscope behaves as it does-- which is easily demonstrated by spinning a bicycle wheel about an axis and the exterting a turning couple to rotate the entire wheel about an axis perp. to the axis of spinning...I got the explanation from...

Kinda like "Being John Malkovitch" but not quite. My scenario deals with historical figures that are dead. What if it were possible to relive someone elses life, watch it on a tv perhaps, AND hear their thoughts as they thought them... We have Einstien's brain somewhere, right? If it were...

Know more about http://www.great-quotes.com/quotes/category/Life" ...

Dokuchaev, "Is there life inside black holes?" I thought this was pretty cool. "Is there life inside black holes?" Vyacheslav I. Dokuchaev http://arxiv.org/abs/1103.6140 Abstract: Inside a rotating or charged black holes there are bound periodic planetary orbits, which not coming out...

Do you have any ideas like something which helps hearing impaired people to communicate with others who don't know sign language, for example a glove, which translates sign language to text which is displayed or even translates it to speech? Any kind of things like that or can be something...

Homework Statement Consider the following reaction NOBr (g) → NO (g) + ½ Br2 (g) The table below gives the time-dependent concentration of NOBr. Using this data, determine, if the reaction is first- or second-order, with respect to NOBr. Give the rate equation and determine the rate...

Hello everybody. I am currently in a French engineering school, one of the best. The hard part was getting into it; now I am pretty assured to graduate and I just have to follow some very basic courses. I could be perfectly happy, except...I'm not really sure I want to be an engineer...

Homework Statement To determine volume of blood in a patient's body, a nuclear medicine technologist is injected a small amount of a radioactive isotope (T(1/2)= 45 min) into the patient's blood stream. The activity of this isotope is at the time of injection was ( 2.8x10^4 decays/second...