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I shove the rod towards Mars one inch, did I just exceed the speed of light data transfer?
Valid question. They may argue that the impulse travels only at speed of sound in the rod, which is <<<< speed of light.
Then again, they may say that the force you exert pushes a few electrons that interact with the photons that go in Drunken Random Walk etc and hence the Mars end won't move for 1,87,000 years (Earth-Mars is > 1 Sun distance, hain?)
^ +3
Ah! I c that the Physics experts beat me to it. Are they great or WHAT?
Last edited by UlanBatori on 28 Feb 2016 05:59, edited 2 times in total.
Silly me. I thought there was a serious discussion going on here. But if it's all fanciful stuff about the sun being a laser or maser and instantaneous communication from earth to Mars using long metal rods, I'm out.
India and Mongolia are likely to kick off talks in March on the $ 1 billion credit line, which Prime Minister Narendra Modi announced during his visit to the country in May 2015.
“We are expecting a delegation from Mongolia to arrive in India in March, to lay down the priority areas for the mega credit line as declared by Prime Minister Modi,” an official familiar with India’s policy for Mongolia, told The Hindu, elaborating that the delegation-level talks between Mongolia and India were expected to focus on the infrastructure, IT, and educational projects.
Sorry to post this quote here onlee...but hopefully it will keep all Mongolians busy writing relevant research proposals instead of trolling Ficcissts.
Q: Why does it take thousands of years for light to escape the Sun?
Posted on August 6, 2013 by The Physicist
Physicist: The original statement is often something like, “It takes tens of thousands of years for a photon to get from the core to the surface of the Sun, but only eight minutes to get from the Sun to the Earth”. This is one of those great facts that the cognoscenti love to throw around, like “did you know that we only use 10% of our brains?”. Unfortunately, like the 10% thing, there are details behind this fact that make it somewhat less interesting and ultimately either false or not even wrong.( )
Talking about how long a photon does anything in the Sun for more than around one nanosecond is a little misleading, because within that time almost every photon in the Sun has been broken apart and/or combined with other photons, leaving them mixed together.
The first tiniest bit of the energy of a photon generated in the core gets to the surface within a couple minutes, and is carried away by photons created there. The many-thousands-of years statistic is useful in that it expresses when about half of a photon’s original energy is bled into space. The last of the photon’s energy is never completely released into space (it’s a “last toothpaste in the tube” sort of thing).
Just because it’s interesting to see it presented at least one or two ways, at least once, here’s some of the math behind the statistics of random walks and “escapes”. This isn’t the most direct method, but it does the job. Also, photons don’t behave this way, so this is more of a “what if” calculation.
If a particle travels, on average, a distance of Δx in a random direction (50/50 for left/right) every Δt time, then the probability, P(x,t), of the particle being at a particular place at a particular time satisfies the equation: ....
fanciful stuff about the sun being a laser..ahm outta here
C what I mean, TSJi? Comes and asks smartalek question: "So are u saying Sun is a laser?". We tell him there ARE such things as stellar Masers, and the Sun is certainly stellar.
Such an inspiring response. Reminds of of Prof. Sussex Bin Pissiki yelling:
Give him a Zero! GIVE HIM A ZERO!
when I tried turning the valve on the Burette in my Physics Lab final exam as a first semester freshman, and the valve came off in my hand and the green goo poured all over the desk.
Then Prof. Swaminathan came by, open shirt and beard and Russkie-returned goonda demeanor and all (Absolute Terror of the Physics Dept), and once the valve was stuck back in again, (I had NO confidence that they had fixed it!) and the Burette refilled, he said:
Ennada! Stopcock thiryathukke theriallaya?
And turned it, and voila! The Powers Above caused the valve to come away in HIS hand, and the green goo poured all over the desk.
At which point, showing the difference between the Sussex-ejjikated pakistan and the Russian-trained Physicist, he ORDERED Doctor Sussex:
GIVE HIM A NEW EXPERIMENT! AND THROW THIS GARBAGE OUT! And son, you will not be penalized. It's THEIR fault!
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UlanBatori wrote:
Nothing has changed from the days of Galil-e-0 or Bruno.
Channeling Sagan..
They also laughed at Bozo the Clown...(or Madam Jalebi, PhD for that matter)
This and trolling from "Galil-e-0" Bruno wannabes is quite old and stale. /disgust/
Unfortunately this kind of nonsense coupled with pseudo science propagates theories like "vaccines will kill children".. As the great poet, Guptji, said about one ills of mother India..
रे मूर्कते जीवित रहे, रक्षक तुम्हारे है धनी. (Long living stupidity, protected by Rich and Powerful
Prof UB, I hope you are proud of the fact that you have raised the entropy of this thread by orders of magnitude. (For those who may not know - Entropy is measure of Disorder)
(Edited and typo corrected : Thanks UB for pointing out the typo)
Last edited by Amber G. on 27 Feb 2016 23:16, edited 3 times in total.
UBji, I never question your ability to communicate difficult matters lightly...but do go easy on hard working, productive and poorly paid physicists...especially the young ones who do most of the interesting work that adds to the reservoir of knowledge. Your take on GW discovery was quite below the belt for no particularly good reason. I am not reporting anyone, so you can rest easy on that.
Back to Lasers or whatever is the flavor of the day. There was an article in yahoo on a UCSB prof (Lubin ?) claiming feasibility of using lasers for faster inter-planetary transport now.
Cladded optical fibres were in use for some time now. A good light guide was a central element of detectors we built as grad students with our bare hands. Scintillating fibers is the fashion now in HEP for good reasons.
Meanwhile back to topic..on how important and significant this LIGO event is being considered in USA:
Leading scientists testifies before US Congress on the significance of LIGO.
Starts with : "LIGO has “cracked open” a new window to the universe"
(And many echo's similar points I put in brf too)
It is a two hour hearing that took place on 24th. It has lot of details and information is nicely presented. The audience is committee members of US congress. For any serious brf jongo, it is worth watching.
Some of the "witnesses" or presenters are: MIT’s David Shoemaker (Kavli Institute for Astrophysics and Space Research, who briefed the House Committee on Science, Space, and Technology on the LIGO effort and how it is expected to benefit science and innovation in the future.) Fleming Crim (assistant director for the National Science Foundation’s Directorate of Mathematical and Physical Sciences) David Reitze (executive director of LIGO at Caltech) Gabriela Gonzáles ( a professor of physics and astronomy and spokesperson for the LIGO Scientific Collaboration)
Among the listeners were 21 Committee members, who expressed strong bipartisan interest in LIGO.
>>> Some points in the video:
LIGO’s recent detection of gravitational waves marks the beginning of a new era for astrophysics, and further insights into black holes, neutron stars, supernovae, and other phenomena are expected before long and how LIGO is expected to benefit science and innovation in the future.( David Shoemaker)
The 21 Committee members, expressed strong bipartisan interest in LIGO.
“The window to this new world of gravitational waves has just been cracked open ..As we open it wider and more and more people look out on the landscape, we will be rewarded with discoveries that will, time and time again, give us all — scientists, leaders, and laypersons — a thrill of understanding of things much bigger than ourselves.”
Gravitational waves will allow researchers to “see” events that produce signals that cannot be seen any other way, he explained. And by combining gravitational wave data and data from traditional instruments, researchers will be able to test theories about fundamental components of the cosmos. These include supernovae, whose explosions modelers still have not managed to simulate, according to Shoemaker, and neutron stars, objects so dense that a teaspoon of their matter would weigh 10 million tons on Earth.
“There will certainly be surprises. Every time we open up a new window to the universe, we see new things, and we’re surprised every time,”
"The rate of new observations should accelerate as the sensitivity of LIGO’s detectors is improved — they currently operate at one-third their potential sensitivity — and as detectors in other countries, such as the Virgo interferometer in Italy, come online"
“With three detectors you can do a great deal more science; you can see where the source is in the sky and you can get an idea of what the polarization nature is. It will really add to what we can learn,” Shoemaker said. It leverages our investment to have…these other projects that are coming along behind us but will supplement the science we can do and will complement the science we get from our own detectors. We are the leaders but with these other observatories we will have a worldwide, global cooperation that will bring us all forward in science.”
There are QA (thankfully, unlike UB and JohneeG's trolling) about practical applications of LIGO (many good examples - are offered like powerful and stable lasers, high-end communications, time-keeping, navigation etc .. ( some of these were presented here in brf by me but sadly lost in noise created by UB and the crowd ): )
Also noted that LIGO has trained a new talent base on the leading edge of science and technology..a large number of students and early-career scientists who worked on the project since been hired by employers as diverse as genomics companies and the Department of Defense.
^^^ Didn't know that..I am pleasantly surprised by the fact that the discussion was quite good.
I also liked that LIGO India's contribution, and India/NaMo's enthusiastic interest for future was shown in positive light multiple times in that hearing. Contrast that with some negative reactions in India and in brf by some.
Amber G. wrote:(I have taken a course in Quantum Mechanics from Dirac, and his text book on Quantum Mechanics is a classic.)
By 'from Dirac', were you referring to his textbook?
Yes I still have a copy of his text book. I have also attended(audited) his lectures (for the whole semester) when he taught introductory QM for an UG course. That was a VERY large class . (this was back in 70's).
Amber G. wrote:Yes I still have a copy of his text book. I have also attended(audited) his lectures (for the whole semester) when he taught QM for an UG course. That was a VERY large class. (this was back in 70's).
Bade wrote:BTW, Dirac also has a textbook on General Relativity, the thinnest ever in the subject.
Also, one of the best and tiniest book on special relativity I own is from none other than great L. Landau! (I bought it in India, a paper back copy for about 1 Rs!)
Viv S wrote:
(Also, what does auditing in this context mean?)
Auditing just means I was not taking it for credit ..(No grades etc.). This was a UG course, but as usual when a good professor teaches, the class had many graduate students (like me) and faculty in the audience.
The last slide in the presentation is of interest perhaps. Also the slide which shows when LiGO-India will come in hopefully and the subsequent improved sensitivity with 3rd gen detectors.
^^^ From the slides linked in Bade's post..
(Just for reference that is easily available in this thread) LIGO India is a GO after 5 years of waiting on the Indian government!
Cabinet grants ‘in-principle’ approval to the LIGO-India mega science proposal
The Union Cabinet chaired by the Prime Minister Shri Narendra Modi has given its ‘in principle’ approval to the LIGO-India mega science proposal for research on gravitational waves. The proposal, known as LIGO-India project (Laser Interferometer Gravitational-wave Observatory in India) is piloted by Department of Atomic Energy and Department of Science and Technology (DST). The approval coincides with the historic detection of gravitational waves a few days ago that opened up of a new window on the universe to unravel some of its greatest mysteries.
The LIGO-India project will establish a state-of-the-art gravitational wave observatory in India in collaboration with the LIGO Laboratory in the U.S. run by Caltech and MIT.
The project will bring unprecedented opportunities for scientists and engineers to dig deeper into the realm of gravitational wave and take global leadership in this new astronomical frontier.
LIGO-India will also bring considerable opportunities in cutting edge technology for the Indian industry which will be engaged in the construction of eight kilometre long beam tube at ultra-high vacuum on a levelled terrain.
The project will motivate Indian students and young scientists to explore newer frontiers of knowledge, and will add further impetus to scientific research in the country.
It was theoretically known that it was possible to "surf" on a gravitational perturbation. But to create and hold that configuration needs some exotic unobtanium kind of as yet unknown material and energy.
UlanBatori wrote:
Ah! I c that the Physics experts beat me to it. Are they great or WHAT?
Me, a physics expert?? My knowledge of physics stops at the undergrad level.
C what I mean, TSJi? Comes and asks smartalek question: "So are u saying Sun is a laser?". We tell him there ARE such things as stellar Masers, and the Sun is certainly stellar.
That was a serious question, saar. But what to do onlee, you see smartalekism everywhere. I really thought there was something I didn't know about the sun, and if you had some gyaan on why it was a laser, you'd have had me eating out of your hand. I thought you were a physics expert (seriously).
I do enjoy your writing style a lot in the political threads, believe me. In a physics thread - wading through five witticisms, three sarcastic allusions, and a couple of obscure inside jokes per post would still be fine, if you also presented some gyaan to go with it. Only, it seems there's really no gyaan buried in all that chamak.
The laser community is well entrenched in physics departments in India, the madrasa in the south being an example to this. In the US the split is more towards EE departments hosting sizable faculty and labs. That was the case in my PG univ, with both departments working on similar things...futuristic wakefield accelerators, plasma driven etc....which means by 2100 we may not need to dig huge tunnels to collide beams in upgrading the energy scale in search of new physics.
Then there are LASERs vs LOSERs etc...endless fun to discuss, but my depth in the field is largely limited to a special topics course we took in our final year to improve our grades.
GIVE HIM A NEW EXPERIMENT! AND THROW THIS GARBAGE OUT! And son, you will not be penalized. It's THEIR fault!
That's funny Boss and amazing too. I never got with in a 100 feet of a full PHD science professor in my freshmen chemistry class and lab. Just not possible. Grad Assistants only and they didn't have a lot of time for you either. Over crowded state university.....if I could only do it all over again knowing what I know now, however little that maybe.......
LIGO India is a GO after 5 years of waiting on the Indian government!
Amberji, that is certainly good news that India is committing to this tech. The more participation the better as far as I am concerned. It also confirms my to me that this new area of science has great potential for major discoveries.
I did finally meet a PHD science degree person when I was in the Marines. I took a night class in introduction to Astronomy at the local junior college in Santa Ana, Ca. The teacher was a freshly minted Phd astronomer from USC. The JC had a planetarium and he was a great teacher. Unbelievably enthusiastic and he really wanted people to know astronomy and the heavens. He would set up his own home made telescope (he hand ground the mirror) outside in the parking lot. It wasn't very good viewing conditions but he still found things for us to look at. He broke the news to us about black holes. This was in 1971. Black holes were not a widely known topic or social meme back then as it is now. He also sponsored trips to the mountains for better viewing.
It was absolutely the BEST EDUCATIONAL EXPERIENCE OF MY LIFE. But I was in the Marines and had to move on. That JC is now called Saddleback College and unfortunately I forget the name of that outstanding teacher. I wish him the best.
If someone is still curious about new acceleration techniques which will further open up the horizon (not the universe) but the understanding of the laws of physics, then his free access article is not particularly bad. Even Phy Today articles on the subject are behind a paywall.
Please read the excellent link that Guptaji posted: Comment 53.
When light is propagating in glass or other medium, it ..is what we call a quantum superposition of excited matter states and pure photons, and the latter always move at the speed of light c. .. A photon is absorbed by one of the dielectric molecules, so, for a fantastically fleeting moment, it is gone. The absorbing molecule lingers for of the order of 10−15s
in its excited state, then emits a new photon. The new photon travels a short distance before being absorbed and re-emitted again, and so the cycle repeats. Each cycle is lossless: the emitted photon has precisely the same energy, momentum and phase as the absorbed one. Unless the material is birefringent, angular momentum is perfectly conserved too. For birefringent mediums, the photon stream exerts a small torque on the medium. It is the fact that the energy spends a short time each cycle absorbed, and thus effectively still, that makes the process have a nett velocity less than c So the photon, on leaving the medium, isn't so much being accelerated but replaced.
Answer to a Comment Question:
But how the ray of light maintain its direction? After it is absorbed by first atom, how does it later knows where to shot new photon again? Where is this information is preserved?
A very good question. This happens by conservation of momentum. The interaction is so short that the absorber interacts with nothing else, so the emitted photon must bear the same momentum as the incident one. Also take heed that we're NOT a full absorption in the sense of forcing a transition between bound states of the atom (which gives the sharp spectral notches typical of thie phenomenon), . It is a transition between virtual states - the kind of thing that enables two-photon absorption, for example - and these can be essentially anywhere, not at the strict, bound state levels. As I said, this is a rough analogy: it originated with Richard Feynman and is the best I can do for a high school student who likely has not dealt with quantum superposition (Oooo! The Snoot-e-ness ul Sussexi shows..) before. The absorption and free propagation happen in quantum superposition, not strictly in sequence, so information is not being lost and when you write down the superposition of free photon states and excited matter states, you get something equivalent to Maxwells equations (in the sense I describe in my answer here or here) and the phase and group velocities naturally drop out of these.
Another way of qualitatively saying my last sentence is that the absorber can indeed emit in any direction, but because the whole lot is in superposition, the amplitude for this to happen in superposition with free photons is very small unless the emission direction closely matches the free photon direction, because the phases of amplitudes the two processes only interfere constructively when they are near to in-phase, i.e. the emission is in the same direction as the incoming light. {hence the laser stimulated emission analogy..cruelly dissed by some hiyar}
All this is to be contrasted with fluorescence, where the absorption lasts much longer, and both momentum and energy is transferred to the medium, so there is a distribution of propagation directions and the wavelength is shifted.
OK, now pls to go read my Florida Turnpike analogy.The flaw in all the above, is that the photon is **NOT** coming in a lane by the side of the particle (electron, per Shri Gupta) but head-on- like a DUI coming into the TollBooth. Since Shri Gupta (or Badeji) declared that the Gamma Ray Photon and the electron have comparable wavelengths, so the momentum transfer can be quite "resonant' (meaning very efficient). IOW, the TollBooth now has a huge increase of momentum, like a carrom coin hit by the striker, and zips off ALONG THE DIRECTION of the incldent photon. So a significant distance is covered in the time b4 emission, the electron is **NOT** sitting still.
This is what is wrong with the blind parroting of "Drunken Random Walk Theory" to this problem, and this is why both the "4000 years" and the "171,000 years) calculation, despite all their Probabilistic mumbo-jumbo, violate conservation of momentum, which is a concept that is taught, I think, in 8th grade.
BUT.. Great Thread! SUCH deep discussions! Thanks, Guptaji.
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Some technical advances which help physics advance...never make the headlines..
Many of the practical aspects of an accelerator are determined by how quickly the particles can be accelerated,” said SLAC accelerator physicist Mike Litos, lead author of the paper. “To put these results in context, we have now shown that we could use this technique to accelerate an electron beam to the same energies achieved in the 2-mile-long SLAC linear accelerator in less than 20 feet.”
“These results have an additional significance beyond a successful experiment,” said Mark Hogan, SLAC accelerator physicist and one of the principal investigators of the experiment. “Reaching the blowout regime with a two-bunch configuration has enabled us to increase the acceleration efficiency to a maximum of 50 percent – high enough to really show that plasma wakefield acceleration is a viable technology for future accelerators.”
Very high energy Gamma rays can pair produce electron pairs, so it is not like some simple scattering with visible photons...So the analogy only goes so far.
I am stepping waaaaaay out of the woods here, but IMVVVVHO there is a problem with your florida turnpike analogy.
Momentum is a quantum mechanical quantity defined by an operator that works on the wave function. The moment a photon interacts with a glass/mirror, the wave function of both of these things merge into one. When that happens, there is no meaning to momentum of a photon, there is no photon anymore, its now a combined wave function of the photon and the atom. You can measure the momentum of that system as such by running the momentum operator on the merged wavefunction.
IMO even after the photon get re-emited there must be entaglement between the inndividual wavefunctions, which means its still the same function until something causes it to collapse (i.e. a detector or some such thing).
In any case, until we measure a property of the photon (such as location or momentum) the photon and the atom that emitted it, and the photon that was absorbed before it, are one single system that exist in a superposition of all possible states.
If a very high energy drunken SUV goes through a toll booth, the toll both will produce two, four or maybe even more toll booths. But momentum transfer remains the same. So the analogy holds there too - the mark of any true physics theory.
Lokesh, Radiation Pressure AFAIK is not what we are discussing. The issue was the Drunken Random Walk theory of gamma photon propagation from the inside of the sun to the surface, which violates conservation of momentum and angular momentum (same thing). Also Guptaji's link says that it is most certainly **NOT** the same photon after each interaction, but an absorption followed by new phton emission. So much for the drunken random walk theory - it is convincingly debunked by the above, so much for all the
DID U KNOW IT TAKES 4000 to 71000 YEARS FOR A GAMMA PHOTON TO TRAVEL 638,000 KM?
hyperventilation.
But you are right in that radiation pressure is indeed momentum flux due to photons, and I am glad you know about it and saw the connection, thanks. So, if radiation pressure can push a solar sail, it can push electrons or whatever else the photon runs into, hain? Q.E.D. and R.I.P. Drunken Random Walk. Back 2 our regular programming.
Wow! This TollBooth Model is better than the Unified Theory, hain?
LokeshC wrote:I am stepping waaaaaay out of the woods here, but IMVVVVHO there is a problem with your florida turnpike analogy.
Momentum is a quantum mechanical quantity defined by an operator that works on the wave function. The moment a photon interacts with a glass/mirror, the wave function of both of these things merge into one. When that happens, there is no meaning to momentum of a photon, there is no photon anymore, its now a combined wave function of the photon and the atom. You can measure the momentum of that system as such by running the momentum operator on the merged wavefunction.
IMO even after the photon get re-emited there must be entaglement between the inndividual wavefunctions, which means its still the same function until something causes it to collapse (i.e. a detector or some such thing).
In any case, until we measure a property of the photon (such as location or momentum) the photon and the atom that emitted it, and the photon that was absorbed before it, are one single system that exist in a superposition of all possible states.
That is not the case with cars on a turnpike.
Ha! I happen 2 have some time, since I am too sick to go on that yakmobile trip to Dera Shikar Khan on the Silk Route tomorrow. First, let's dispense with the E-Z-R objections to TollBooth Unified Theory (TUT):
even after the photon get re-emited there must be entaglement between the inndividual wavefunctions, which means its still the same function until something causes it to collapse
Have u seen a tollbooth after a DUI SUV went through it at Mach 0.12? I'd say pretty entangled.
The moment a photon interacts with a glass/mirror, the wave function of both of these things merge into one
Aha! So all those ppl building Solar Sails r full of pakistan? I think they have cleanly defined the momentum transfer based on whether it is absorption (black/whatever coated, photons ride along with sail), or reflection (shiny, photon reflects back where it came from). The latter give twice the push as the former, to the sail, and this is verified, no speculation about it. So it IS that simple.
Now I will dig deep into the pockets of my yakmobile and take out this RPG/TOW: Ask u 2 pls go c y Andrei Sahkarov got the No-Bill-Pissicks Prize. OK, it was because they wanted to create a hoohah since he was a dissident and they wanted to make the Soviets uncomfortable, but his work was pretty awesome. He showed (in public literature) why fusion happens inside stars, and radiation pressure was a big part of it. Basis of all bum-e-H2.
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The main thing to understand about the solar core is that the mean free path, the average distance a photon can travel unimpeded, is very small, about 10^-5 meter (or whatever the figure it was that I quoted before. Why don't I remember? I claim the right to have senior moments). The identity of a photon itself is a problematic thing, and so "it takes 4000 or 171,000 years for a photon to make its way from the core to the surface" is a bit of poetry, and should be taken as such.
When protons fuse in the Sun's core, the gamma rays that are produced have no preferred direction of movement; they have no idea of what direction is towards the core and what is towards the surface. This is quite unlike your cars on the highway with toll booths.
Let us also assume that instead of cars we have heavily loaded trucks, and in their collisions with toll booths they get deflected upto +/- 0.1° with respect to their original direction, because they carry most of the momentum. Consider that these trucks are meeting 10^5 toll booths per meter, and figure out on the average how far a truck might go before it is completely turned around.
Also consider this different line of argument. The energy produced in the sun's core resides there for a while; if it shoots out too soon, the equilibrium temperature will be too low to sustain the rate of energy production, the core will shrink until a new equilibrium is established; if it shoots out too slowly, the temperature will rise, energy production will go up, and the core will expand until a new equilibrium is established.
Here is my attempt to reason (btw, I never claimed it was the SAME photon, I only said energy.... it take about that many years for energy to come out from the core). Light getting scattered is not the same as light passing through a transparent material (IMHO).
Let me give you a mechanics problem:
I have a spring system that locks the spring in the compressed form. The spring is not perfect and there is some loss of energy as heat/friction etc. The lock disengages after a random time and the spring is released.
The spring is attached to a wheel (which is attached to a shaft) on one side and has a basket (to catch objects) on the other side. Assume that the wheel is rotating initially (it has an initial angular momentum of some sorts).The spring also *could* release only partially in one instance. If it has to release again, it will push another ball out. { EDIT: That would violate momentum conservation . So for now lets assume we got a really rusty spring that dissipates some part of the internal energy increase (due to inelastic collision) into heat. }
Now a ball at super high velocity hits the basket, the spring compresses and the lock engages. This is a completely inelastic collission. Now the wheel turns and after a random interval disengages. The ball is now let go with a lower velocity at a random direction. The wheel is very heavy so it has barely moved.
Imagine the same system with a billion wheel/shaft/spring system interconnected with springs of their own and a trillion balls thrown at them per second.
If a ball travels 1 million miles per second (ignore the speed limit for now), How much time would it take for a ball to cross a billion miles thickness of such an arrangement?
Momentum is conserved? Correct?
Last edited by member_22733 on 29 Feb 2016 03:14, edited 1 time in total.
instead of trolling Ficcissts.
)
My knowledge of physics stops at the undergrad level.