John Dalton Atomic Theory

John Dalton was an English chemist, physicist and meteorologist. He was the first man whose proposed atomic theory was accepted. Dalton is also known as discoverer of color blindness. In the research, on the properties of atmosphere and gases in 1803, he discovered about atoms and their weights. It was published in 1805.



Dalton declared the six elements of the first table on the basis of relative atomic weights. It included hydrogen, oxygen, carbon, nitrogen, phosphorus and sulfur. He placed the hydrogen with atomic weight 1. However, he failed to confirm the reason for atomic weight. In September 1803, he found the relative weight of water, carbon dioxide and ammonia and also discovered the symbol representing the element.



In 1803, Dalton gave a lecture in London regarding the relative weight of elements. He said that an atom was the smallest particle of any element and it cannot be destroyed. Atoms of the same element are similar in weight and this weight is different in different elements. Chemical reaction is the result of rearrangement of atoms and it combines in the 1:1, 1:2, and 2:3 ratios. A chemical compound is formed by the combination of two or more different elements.



In the New System of Chemical Philosophy, Dalton issued the elements with their atomic weights and for this work he got Royal Medal in the year 1826. The mass of elements was termed as atomic weight.



Source:http://24hoursofculture.blogspot.com...theory_14.html

Is The Universe A Hologram? Physicists Say It's Possible

A team of physicists has provided some of the clearest evidence yet that our Universe could be just one big projection.



In 1997, theoretical physicist Juan Maldacena proposed that an audacious model of the Universe in which gravity arises from infinitesimally thin, vibrating strings could be reinterpreted in terms of well-established physics. The mathematically intricate world of strings, which exist in nine dimensions of space plus one of time, would be merely a hologram: the real action would play out in a simpler, flatter cosmos where there is no gravity.



Maldacena's idea thrilled physicists because it offered a way to put the popular but still unproven theory of strings on solid footing — and because it solved apparent inconsistencies between quantum physics and Einstein's theory of gravity. It provided physicists with a mathematical Rosetta stone, a 'duality', that allowed them to translate back and forth between the two languages, and solve problems in one model that seemed intractable in the other and vice versa. But although the validity of Maldacena's ideas has pretty much been taken for granted ever since, a rigorous proof has been elusive.



In two papers posted on the arXiv repository, Yoshifumi Hyakutake of Ibaraki University in Japan and his colleagues now provide, if not an actual proof, at least compelling evidence that Maldacena’s conjecture is true.



In one paper, Hyakutake computes the internal energy of a black hole, the position of its event horizon (the boundary between the black hole and the rest of the Universe), its entropy and other properties based on the predictions of string theory as well as the effects of so-called virtual particles that continuously pop into and out of existence. In the other, he and his collaborators calculate the internal energy of the corresponding lower-dimensional cosmos with no gravity. The two computer calculations match.



“It seems to be a correct computation,” says Maldacena, who is now at the Institute for Advanced Study in Princeton, New Jersey and who did not contribute to the team's work.



Regime change

The findings “are an interesting way to test many ideas in quantum gravity and string theory”, Maldacena adds. The two papers, he notes, are the culmination of a series of articles contributed by the Japanese team over the past few years. “The whole sequence of papers is very nice because it tests the dual [nature of the universes] in regimes where there are no analytic tests.”



“They have numerically confirmed, perhaps for the first time, something we were fairly sure had to be true, but was still a conjecture — namely that the thermodynamics of certain black holes can be reproduced from a lower-dimensional universe,” says Leonard Susskind, a theoretical physicist at Stanford University in California who was among the first theoreticians to explore the idea of holographic universes.



Neither of the model universes explored by the Japanese team resembles our own, Maldacena notes. The cosmos with a black hole has ten dimensions, with eight of them forming an eight-dimensional sphere. The lower-dimensional, gravity-free one has but a single dimension, and its menagerie of quantum particles resembles a group of idealized springs, or harmonic oscillators, attached to one another.



Nevertheless, says Maldacena, the numerical proof that these two seemingly disparate worlds are actually identical gives hope that the gravitational properties of our Universe can one day be explained by a simpler cosmos purely in terms of quantum theory.



Source:http://24hoursofculture.blogspot.com.../hologram.html

negative binomial distribution

1. The problem statement, all variables and given/known data



Repeatdly roll a fair die until the outcome 3 has accurred on the 4th roll. Let

X be the number of times needed in order to achieve this goal. Find E(X)

and Var(X)



2. Relevant equations







3. The attempt at a solution



I am having trouble deciphering this question. Is the first sentence saying to roll a die until you get a 3 on the fourth roll? thus the event of a success is when you get a 3 on the fourth roll? but what is number of successes? which you need to know in order to find the mean in a negative binomial distribution.



Apparently E(X) = 24.

Are there any jobless graduates from Harvard?

Is there any graduate from Harvard that can't get a job? If so, then what's the point of going to Harvard?

Our picks for fourth quarter 2013 MIP (most important QG paper)

Of the twenty candidates, indicate the ones you think will prove most significant for future QG research. I've included two papers from earlier in the year which I mistakenly overlooked when they first appeared. Since the poll is multiple choice, it's possible to vote for several papers. Abstracts follow in the next post.



http://arxiv.org/abs/1312.7273

On How Neutrino Protects the Axion

Gia Dvali, Sarah Folkerts, Andre Franca

(Submitted on 27 Dec 2013)

9 pages



http://arxiv.org/abs/1312.3657

Structural aspects of loop quantum gravity and loop quantum cosmology from an algebraic perspective

Alexander Stottmeister, Thomas Thiemann

(Submitted on 12 Dec 2013)

45 pages



http://arxiv.org/abs/1312.3595

Hawking radiation from a spherical loop quantum gravity black hole

Rodolfo Gambini, Jorge Pullin

(Submitted on 12 Dec 2013)

13 pages



http://arxiv.org/abs/1312.3253

General Relativity from a Thermodynamic Perspective

Thanu Padmanabhan

(Submitted on 11 Dec 2013)

53 pages



http://arxiv.org/abs/1312.1538

Gravitational Energy, Local Holography and Non-equilibrium Thermodynamics

Laurent Freidel

(Submitted on 5 Dec 2013)

41 pages, 3 figures



http://arxiv.org/abs/arXiv:1312.0905

Quantum group spin nets: refinement limit and relation to spin foams

Bianca Dittrich, Mercedes Martin-Benito, Sebastian Steinhaus

(Submitted on 3 Dec 2013)

30+5 pages, many figures



http://arxiv.org/abs/1311.7565

Time evolution as refining, coarse graining and entangling

Bianca Dittrich, Sebastian Steinhaus

(Submitted on 29 Nov 2013)

33 pages, 9 figures



http://arxiv.org/abs/arXiv:1311.6117

The Koslowski-Sahlmann representation: Gauge and diffeomorphism invariance

Miguel Campiglia, Madhavan Varadarajan

(Submitted on 24 Nov 2013)

45 pages.



http://arxiv.org/abs/1311.5325

Note on the super inflation in loop quantum cosmology

Kui Xiao, Xiao-Kai He, Jian-Yang Zhu

(Submitted on 21 Nov 2013)

9 pages, 4 figures. Physics Letters B



http://arxiv.org/abs/1311.3279

Null twisted geometries

Simone Speziale, Mingyi Zhang

(Submitted on 13 Nov 2013)

22 pages, 3 figures



http://arxiv.org/abs/1311.2898

Matter matters in asymptotically safe quantum gravity

Pietro Donà, Astrid Eichhorn, Roberto Percacci

(Submitted on 12 Nov 2013)

22 pages, 18 figures, 4 tables



http://arxiv.org/abs/1311.0186

Twistor relative locality

Lee Smolin

(Submitted on 1 Nov 2013)

10 pages



http://arxiv.org/abs/1311.0054

Relative information at the foundation of physics

Carlo Rovelli

(Submitted on 31 Oct 2013)

3 pages. Second prize in the 2013 FQXi contest "It From Bit or Bit From It?"



http://arxiv.org/abs/1310.7786

Group field theory as the 2nd quantization of Loop Quantum Gravity

Daniele Oriti

(Submitted on 29 Oct 2013)

23 pages, 5 figures



http://arxiv.org/abs/1310.6728

Quantization ambiguities and bounds on geometric scalars in anisotropic loop quantum cosmology

Parampreet Singh, Edward Wilson-Ewing

(Submitted on 24 Oct 2013)

34 pages



http://arxiv.org/abs/1310.5167

A Gravitational Origin of the Arrows of Time

Julian Barbour, Tim Koslowski, Flavio Mercati

(Submitted on 18 Oct 2013)

44+14 pages, 8 figures, 1 table



http://arxiv.org/abs/1310.3362

Deformation Operators of Spin Networks and Coarse-Graining

Etera R. Livine

(Submitted on 12 Oct 2013)

24 pages



http://arxiv.org/abs/1310.2174

Radiative corrections to the EPRL-FK spinfoam graviton

Aldo Riello

(Submitted on 8 Oct 2013)

13 pages, 4 figures



http://arxiv.org/abs/arXiv:1309.0352

Cosmological perturbations in teleparallel Loop Quantum Cosmology

Jaime Haro

(Submitted on 2 Sep 2013)

18 pages. Journal of Cosmology and Astroparticle Physics



http://arxiv.org/abs/1306.1058

Quantum gravity from the point of view of locally covariant quantum field theory

Romeo Brunetti, Klaus Fredenhagen, Katarzyna Rejzner

(Submitted on 5 Jun 2013)

51 pages

Inertial motion in GR

Does inertial motion (understood in the SR sense) exist in a curved spacetime?

image problem

1. The problem statement, all variables and given/known data

I found that the blurred image is always presented by

$$A=Ku+f$$, where u is the perfect image source, and the K is transformation (blurring, sampling)

and f is the noising . The question I want to know is how can we find such K, or f when we blurred the image , for example ,using the gaussian blurring.

In other word, I want to know how can I find K or f s.t. I can do the same effect as using the

imnoise function in matlab as gaussian blurring or ...





2. Relevant equations

I found that there are matrix related to it, where the matrix is given by h=fspecial('gaussian',256);

and it is all zeros.





3. The attempt at a solution

Questions about edX (opencourseware) on college resume?

This coming semester, the only courses I have left to finish my AA are Calc III, Physics II, and ODE. So, I figured I would take some additional opencourseware since I will have the spare time. On that note, I was hoping some of you might give me insight into some questions I had regarding opencourseware from edX that awards you certifications on completion:



1. Is it worth earning the certifications on edX or just audit at your own pace? Do colleges really consider those types of "badges" to have any accreditation at all?



2. Tying into question 1, is it worth putting completed opencourseware on your college resume for grad schools? If so, should it only be ones you can back up with certifications? For example, I took MIT's physics 8.01 in conjunction with my college's course to complement it, but only audited it (no cert.). Should things like that be added to the resume?



3. I know for physics majors, grad schools like to see linear algebra, which is one of the courses I plan to take on edX soon. Would that be acceptable as having learned it, or should I have the course on my college transcript?



Anyway, I know regardless of what grad schools think of it, the OCW is a great addition to my education. It's always great seeing courses from another perspective where there are different focuses. The MIT OCW is also far more comprehensive than my college's courses. I'm just wondering what would be the best way to display that additional education to grad schools?

Physics and Philosophy Books Help

Hi there folks!



I am new to the forum and would like to thank anyone in advance for their answers as I will not be able to check them until late tomorrow night.



I love physics, but not as much as my niece and I have a gift to give and I think I found the best people to set me in the right direction (possibly with enough ideas for years to come)



Due to her personal interests and recent life experiences I am looking for something along the lines of the "Dancing Wi Lu Masters" but more updated as she is very current on her studies.



Book recommendations for people familiar with the subject of physics at any level (except expert) that explores its connections to the other disciplines primarily theology, ideology and philosophy.



Reasons for selections appreciated.

Molar Heat of Neutralization

1. The problem statement, all variables and given/known data



Calculate the molar neutralization heat of nitric acid (HNO3) using the following data:



Before Neutralization:



HNO3 (0.5 mol/L)

V = 200 ml

T= 23 Celsius



LiOH (1 mol/L)

V = 200 mL

T = 25 Celsius



After Neutralization:



V = 400 mL

T = 27.5 Celsius



2. The attempt at a solution



Calculating the total heat released by Nitric Acid:



q=mcDT

= (400)(4.184)(27.5-23)

= 7531.2 Joules



Calculating moles of Nitric Acid:



C= n/v

(0.5 mol/L) x (0.2) = 0.1 moles Nitric Acid



Calculating Molar Heat of Neutralization:



= (-7532.2 Joules / 1000) / (0.1 moles)



= -75 KJ / mol



Can someone please verify if this is done correctly? Thank you.

Math Class To Self-Study?

Hi, I'm a Junior in high school. I just finished Calculus 3 (and got an A) last semester and I'm taking Differential Equations next semester. Also (if I get in to this free math program), I will be taking Linear Algebra and Number Theory with Cryptology this summer. Anyways my question is what math subject would be good to self-study (that I wouldn't be repeating much by taking the classes I mentioned)? Would Discrete Mathematics be a good idea? Also how would you recommend I self-study, just textbook and problems? Also please suggest good textbooks and other resources. Thank you

Praise New Year's Eve Chat is open!!!

Come join the fun!



Bring your hats and party favors!! Help us usher in the New Year on Physics Forums!!



http://www.physicsforums.com/misc.php?do=flashchat

Differences Between Different Thermo Classes

Also sorry if you feel this is in the wrong place. I was unsure where to put it. I was wondering what the main differences in content/way problems are solved in Mechanical Engineering Thermodynamics, Chemical Engineering Thermodynamics, Thermodynamics of Materials ( for MSE), Thermal Physics, and the Thermodynamics part of Physical Chemistry. I'm asking this partly due to curiosity and partly since I'm taking Physical Chemistry this upcoming semester and considering taking (Mechanical Engineering) Thermodynamics over the summer.Thank you for taking the time to read this and hopefully for answering.

Gravity - Why do we Use Radius of Earth in Calculating Surface Gravity

Newton showed that F=G(m1m2)/r2



When calculating the force of gravity on the surface of the Earth, why do we use the radius of the Earth for our r value? Of course, the above Newtonian equation suggests we should, but it seems rather counter-intuitive.



I must admit to not having taken a relevant course since an Honors Physics course in high school. If we were ever given a logical explanation (with minimal calculus required) for this, I cannot recall it. I have also posed this question to a friend of mine who, while not a physics major, attended a small, but well respected, science and engineering school in Southern California. He could not recall an answer to this question, though he did remember learning about Shell Theorem. Despite my limited understanding of Calculus, Shell Theorem does make some degree of logical sense.



In any case, my question is this: Since the mass directly under my feet contributes significantly more gravitational force than the equally dense mass on the opposite side of the Earth (in a spherically symmetrical Earth where density only varies by depth), shouldn't the center of gravity be somewhat closer to me than the center of the Earth?



If I were to compose a fictional earth consisting of tens of thousands of spheres, of say 100km radius, would I not find that the sphere directly below my feet with radius=100km contributes many magnitudes more force than the sphere opposite it with radius= approx 12,500km? By my calculations the nearer 100km radius sphere would exert over 15,000 times the force of the sphere on the opposite side of Earth.



I have been unable to find a satisfactory answer to this quandary (based on my limited knowledge of both physics and calculus).



I have tried a variety of sources, but keep getting answers similar to this one from, groan, Wikipedia:



"If the bodies in question have spatial extent (rather than being theoretical point masses), then the gravitational force between them is calculated by summing the contributions of the notional point masses which constitute the bodies. In the limit, as the component point masses become 'infinitely small', this entails integrating the force (in vector form, see below) over the extents of the two bodies.

In this way it can be shown that an object with a spherically-symmetric distribution of mass exerts the same gravitational attraction on external bodies as if all the object's mass were concentrated at a point at its centre.[3] (This is not generally true for non-spherically-symmetrical bodies.)"





It seems logical that if the two masses are sufficiently far apart, r would approach the distance from their centers, and yet on the surface of the Earth where the distance is relatively short, my brain cannot comprehend how this is so.



Is someone able to explain the above in a manner that makes logical sense to someone with my limited math and science skills and is consistent with Newton's Law of Gravitation? How would you demonstrate this to an intelligent Undergraduate who is unable or unwilling to do the vector math that appears to be required.



Thanks and I have already learned a great many things from the superb minds on this forum.

internal combustion engine calculations.

Hello everybody,



I am working on the whole vehicle calculations, engine, brakes, suspension and engine simulation, using that software, take a look:



http://www.speed-wiz.com/calculation...conditions.htm



That software, you input the values at the top, and it calculates and outputs the results shown in the bottom of the screen



my work is to get the formulas which are used to get those ouputs, and i am just stuck with the intake air density, of those inputs in the screen i sent.



well, here are the formulas i used for "outside air density" calculations, and it gave me 0.0771 Ibs/cubic.ft, see how i got it, to help you understanding what i am requiring, for the "intake air density".





3- outside air density:

By substituting in the formula: Density = P / (R * T)

Where p: is the outside air pressure (Ibs/inch^2),



R: is the Gas constant = 53.35 (ft-lb)/ (lbm•R), and T: is the outside air temperature in °R,



And to convert P from (Ibs/inch^2) to (Ibs/ ft^2), we divide by (0.083) ^2, so we get:



Air pressure P = 14.68 /.083^2 = 2130.933 (Ibs/ft^2), so we get:



Density = 2130.933/ (53.35*518.67) = 0.077I Ibs/cf.




i am sure we will use same formula, but how can i calculate or get the intake air pressure to substitute in that formula, as the R is known, and T: is the intake air temperature is given as 80 F in the inputs.



hope anyone familiar with internal combustion engines help me with that,

will appreciate your help a lot,

Thanks.

how to figure the initial guess to optimize

I have the following problem to code using python:



I have 7 parameters: x,y,z,t, HF, M1F, and M2F. The user should input any of these 3 and the program should calculate the rest.



The relations that I have are:



HF = -xyt



M1F = -2xzt + 4yzt - xyt + 4tz^2



M2F = 2yzt - xyt



1 = -2xt + 2yt + 4zt



Attempt to solve the problem:



I have 7 parameters and the user should input 3 => I will be left with 4 parameters. So it's all about solving a system of 4 nonlinear equations with 4 unknowns.



I read online that scipy.optimize could be used to solve a system of nonlinear equations. But I need an initial guess.



Going back to the physics of the problem I have the following initial conditions:



x > 0



y > 0



z < 0



HF > 0



M1F > 0



M2F > 0



M2F > M1F (solving this inequality from the above equations I get: -x + y + 2z < 0)



HF > M1F + d (solving this inequality from the above equations I get: -x + 2y + 2z < 0)



How can these initial conditions help me get the initial guess so that I can solve my problem using scipy.optimize?

Magnetic Flux Propagation?

Hey all,



I'm working on a project now where I am using a solenoid driven at a 10Hz AC current to create a magnetic field on a solid piece of low carbon iron, and then using a smaller solenoid to capture the magnetic flux coming from the iron.



By measuring the phase of the resulting waves from the drive coil and the sense coil I notice that the phase difference between the two coils increases as I move the sense coil away from the drive coil. This tells me that there is a measurable delay between the transmission of the magnetic flux into the iron, and when that flux is picked up by the sense coil. It also seems to depend on the distance from the drive coil.



Can anyone give me a reason that this might be happening or some theory behind this? I was under the impression that magnetic flux moved at the speed of light, but this might have to do with the magnetic domains aligning as H changes.



Thanks!