What is Impossible: Definition and 298 Discussions

Why is impossible measurement of the magnitudes when his values are smaller than Planck units??

Let me set up a situation: A piano rests on a frictionless surface. I am standing next to the piano (on a frictional surface) and I claim that the following two statements prove it is impossible for me to move the piano: (1) ... The kinetic energy of the piano is equal to the work I've done on...

Is there general consensus that the universe is to young? arXiv:1506.01377 [pdf, ps, other] The Impossibly Early Galaxy Problem Charles L. Steinhardt, Peter Capak, Dan Masters, Josh S. Speagle Comments: 7 pages, submitted Subjects: Astrophysics of Galaxies (astro-ph.GA) The current hierarchical...

So further confirmation from NASA that this might work. Anyone has any explanations on how this could work? I find it fascinating. http://io9.com/new-test-suggests-nasas-impossible-em-drive-will-work-1701188933 http://www.nasaspaceflight.com/2015/04/evaluating-nasas-futuristic-em-drive/

I know this may not be a typical question for the Physics board. I am a MA Design student working on a project to illustrate experiments on speculative/fictional physical events. My final work will consist of strongly simplified staged experiment lab situations and should touch on the imaginary...

Homework Statement In probability theory, i) The events A and B are equal with probability 1 iff P(A)=P(B)=P(AB). ii) The events A and B are equal in probability if only we know P(A)=P(B) iii) From (i), if an event N equals the impossible event with probability 1, then P(N)=0. Additionally...

Would you agree with me that the following question is impossible to do ,it's from A level physics paper 1980 multiple choice question no. 4 .A 5 gram pellet is fired vertically into 95 grams of clay at a velocity of v metres per second calculate the height the clay will reach

I am new to relativity. I noticed that there is a general concept that someone sitting in the inertial frame (a typical one) will not be able to decide whether he/ she is at rest or moving with a constant velocity. Is this true. Are there no advanced devices that can help that person to decide...

Homework Statement I have a rectangular PV diagram of a heat engine. Like this one: I have to show why this cannot work in reverse as a refrigerator. Homework Equations U = 0.5fnRT (U = internal energy, f = degrees of freedom, n = number of moles of gas, R = ideal gas constant, T =...

Homework Statement In terms of the energy involved (using formulas provided), explain why accelerating a spacecraft to the speed of light is impossible. Homework Equations time, mass and length dilation formulas, and a few astrophysics formulas, E = Ek + mc2, projectile motion formulas The...

I remember someone telling me that it's impossible to create a program that determines whether a given program runs forever, and that this requires a rigorous and long proof. Well, I was thinking about that today and the proof should be trivial -- shouldn't it? Proof. Let P be the set of all...

NASA confirms ‘impossible’ thruster actually works, could revolutionize space travel http://www.digitaltrends.com/cool-tech/nasa-confirms-impossible-space-drive-actually-works-revolutionize-space-travel/#!btQgmZ Is there any explanation for why this produces a thrust? Does it have to...

I"m running through a couple options right now in my job hunt. I am a career changer who is aspiring to become an actuary. I only have 1 exam, and after a few months of job hunting without success for entry level actuarial, I have decided I also need to consider 'related' jobs, so I can make...

Forgive my ignorance, but If time exists , why is it impossible to travel through it ? From what I know, it is impossible to travel into the past, and also time dilation doesn't really make one travel into the future cause that would mean satellites would've been long gone since things can't...

(I am sorry, totally forgot about solving quadratic equations, close the topic please) Homework Statement Finding derivative of the equation like F(x) = 5x / (1+x^2) by definition (ƒ(a+h) - f (a))/h is easy (point 2;2), but I got really stuck in finding a way to solve it by basic...

Homework Statement For a UVa problem, I am working on constructing a rooted tree with the following constraints. 1. A tree of depth D means that the tree should contain at least 1 node which is exactly D distance away from the root and there is no node of more than D distance from the...

This has been bugging me. Several respected propulsion scientists at the 2008 Joint Propulsion Conference claimed that interstellar travel within a human lifetime was impossible. The KE of a rocket traveling at a significant fraction of c would be enormous via KE=0.5 * m * v^2 and that...

A bunch of bananas hangs from the end of a rope that passes over a light, frictionless pulley. A monkey of mass equal to the mass of bananas hangs from the other end of the rope. The monkey and the bananas are initially balanced and at rest. The rope is infinite, so the monkey can't just drag...

If someone wanted to travel back to a certain moment in time, then logically every atom in the universe would have to be in exactly the same position in space as it was at that time, the energy level of the atoms would also have to be the same and the position of the electrons in the atoms would...

I am an out of state applicant who has just accepted admission at New Mexico Tech. I really want to go to NMT and I am very excited for the fall, but I heard that is a very hard school. I was just wondering is a 3.0 GPA is possible to obtain, because if I don't have a 3.0 or higher then I will...

Sorry, strange question, but let's do a thought experiment: if a train was moving at near light speed and hit a slow moving object on the tracks, would the two timelines synchronize? since the train is moving at near light speed, according to relativity, time on the train would slow down...

i wrote a script that codes phrases for me in c++ that should be impossible to solve if anybody can solve the code i'll respond with the key and explain how it works so here it is 05 08 13 52 19 55 89 44 33 77 10 82 88 84 23 65 46 52 57 95 37 93 18 11 29 40 69 34 97 87 21 52 17 33 86 20 37 96...

I mean in the traditional sense I know you can probably be a polymath in any variety of subjects. But I refer to those that are philosophy, mathematics and physics which naturally lead to engineering and probably computer science. Now I don't mean a complete expert in each of these fields...

is there a closed form solution for this double integral? \int^{2}_{1}\int^{3}_{4}\sqrt{1+4x^{2}+4y^{2}}dydx

Hi, I know the common proof of the no-cloning theorem assuming the cloning apparatus acts unitarily on the system and leading this to a contradiction. But what about a non-unitarian apparatus that involves measurements? I'm pretty sure cloning is still impossible, but I don't know how to...

Homework Statement A curve of radius 67 m is banked for a design speed of 95 km/h. If the coefficient of static friction is 0.30 (wet pavement), at what range of speeds can a car safely handle the curve? Homework Equations I drew this freebody diagram. The Attempt at a...

Is it impossible to separate a distance of "1light hour" in space? i was having a debate with a guy on a site and he argues it is impossible to separate such a distance in space. Suppose two observers A & B they are relatively at rest, A wish to do an experiment so A & B moves apart by sending...

I haven't found a comparison like this in any book that I have been reading so let me explain. I decided that I will derive an equation for an energy levels of a particle in an infinite potential well in two ways. 1st I tried to derive it using the interval ##0<x<d## where ##d## is a width of...

Sorry if this is the wrong place to ask this, but I think linear algebra is the best place to ask my question. Feel free to move this thread elsewhere if I am wrong. I would like to know how I can use linear algebra to help me figure out when I am deriving an equation if the derivation I...

i had a thought to stick two diodes together such that the electronic setup was similar to that of a BJT transistor. however i have been told by multiple teachers/professors that the two were not equivalent. I have drawn a picture to show you what i mean. the top two pictures are just the...

Everytime I look this up, the answer always is "because mass increases as you approach C, therefore infinite energy is required.", but from what I understand, Relativistic Mass is a misconception and there's no actual increase in mass. So if infinite energy is required, then why? And why else...

Yeah, all of those things, multipled by five thousand, and there we have the current cosmic predicament for human beings. Is there any way in which we can do something about this? Or will Schopenhauer have the last laugh?

Homework Statement https://wiki.math.ntnu.no/lib/exe/fetch.php?hash=d26b1f&media=http%3A%2F%2Fwww.math.ntnu.no%2Femner%2FTMA4115%2F2012v%2Fexams%2Fkont.eng.pdf Assignment 1. "Find all complex numbers s such that Im(-z + i)= (z+i)2" What do I do? Homework Equations The Attempt at a...

well,i have heard this in many threads. That we can only measure the speed of light by noting down when light completes its full round trip. Now why cannot we measure speed of light by considering the half-way trip?

Arnold, an in interview with Lui in Notices of the AMS, Volume 44, no 4, p432 says: "It is a far-reaching generalization of the well-known fact of the impossibility of acoustic communication in the even-dimensional spaces (for instance, in the “plane” world), while in our three-dimensional...

First, I want to apologize for my ignorance and for misplacing this thread if there is a cosmology forum it would better fit into. My question is as follows. The universe is expanding at an ever-accelerating rate. Will the rate of expansion ever exceed the velocity of virtual photons traveling...

1. Why is the following situation impossible? Two parallel copper conductors each have length , L = 0.500 m and radius r = 250 mm. They carry currents I = 10.0 A in opposite directions and repel each other with a magnetic force FB = 1.00 N. Homework Equations 3. I am thinking...

Homework Statement For all integers n, it is impossible to have a solution to the equation 4^n = a^2 + b^2 + c^2 where a, b and c are all positive integers. (Hint: Notice that 4^n = 2^2n is a perfect square. Show (prove) that if m^2 = a^2 + b^2 + c^2, then we must have that a, b and c...

$$y+siny=x$$ How would you even graph a function like this if you can't solve for y explicitly?

I love the internet, but I can't concentrate on working because of it! I sit down at the desk (which is where the computer is), open my book and try to get something done. As I'm reading, if I need further clarification on something I'll look it up, which is where the problem lies. I get so...

Homework Statement A professor gave a pipe network problem to be solved by the Hardy-Cross method. However when I attempted to create a scale drawing of the figure to get a better idea of the problem I realized it is physically impossible to create his design. Now i am wondering if because of...

My guess is that this topic has been covered somewhere at some point. However, I have not recently seen a general, more non-technical treatment of the subject, so I thought this may be the thread for it. In any case, for discussion purposes, I'm going to make the bold statement that time...

Complcated Chemistry Reaction - impossible?? Help :( My notes say: Step 1 is a 221 reaction. If peroxides are used in your version, then the anti-Markovnikov bromide is formed. If your version had only HBr, the the Markovnikov bromide is formeed. Step 2 creates organolithium or Grignard...

Hydrostatic problem - Impossible integral! Just studying hidrostatic over the internet and I saw the following problem: A U-Tube filled with water, initially at rest in a horizontal table, has A1=40cm2, A2 = 20cm2, A3=30cm2, h1 = 80cm, h2 = 20cm and L = 100cm (below piture). It is pressed in...

Is the fact that no one has ever traveled back in time from the future a proof that traveling back in time is impossible? But if a person can travel back in time doesn't that mean relative to the people in the past the future would seem like it has already happened?

I was trying to think of more impossible electric fields than my book has. I understand it is anything that breaks the rule that the path integral is zero. One example is a circular field. I was trying to picture some more complicated 3d examples. Are all magnetic fields an impossible...

Urgent help needed with finding angular speed? This is impossible! I've even asked on Y!A and THEY all got it WRONG. Webassign says the answer is 32.9 but how? This is so freaking frustrating...anlfdsfjlkdjf Ok...so what I tried doing was ask myself what the equation for angular speed was.ω...

c, d, and e I don't know how to solve For d I tried doing vf2 = vi2 +2ad Vf = √(2*9.8*2.3) = 6.71 m/s Assuming the inclined plane is frictionless Since m2 is roped to m1, it's velocity up the ramp will be 6.71m/s too The total increase in KE is then 0.5[8+6]*6.71^2 = 315.16 J ^...

How is causality usually proven when it's impossible to change the independent variable? Also, why is correlation often treated as a very reliable hint to causation, even in various respected journals? Here's an example...

This is a paradox that has been bothering me since I was taking algebra in high school. Let's say that I want to represent the distance between to objects. Given that numbers are infinite in both directions, by which I mean that there is no limit to how large, or small a number can be, there...