Nicholas Kang

According to the equivalence principle, gravity and acceleration are the same thing. Try studying Einstein`s Theory of Relativity, that deals with non-linear motion of relative moving objects. Strictly speaking, if you study Einstein`s special theory of relativity, you will find out that as speed increase, the mass of an object will increase. Such phenomenon are only obvious when speeds approach appreciable fractions of the speed of light in vacuum, c. I haven`t study GR, though, as it is too hard for my level. Second thing, by invoking E=mc2 , mass and energy are equivalent. Thus apart from increase in mass, an increase in energy will also result in increase in gravitational field strength. In fact, you car`s tyre has gravity, since moving gas/air particles in it has momentum, thus posses pressure. And since the particles are moving very slow compared to the speed of light, they pose relatively weak gravity. Not to mention E=hv, which is an equation derived from Quantum mechanics, relating energy and frequency of quantum/microscopic particles. What is gravity? Is it an effect? It is an effect of its own and it affects other objects lie in its "pathway"-curvature of space-time. It bends light, distort images form distance galaxies and quasars, creating Einstein`s Ring and Einstein`s Cross. Gravity creates gravity as in space-time continuum. What is gravity? The answer depends on your perspective. Scientifically, gravity is FG=M1m2/r2 This classical mechanics, derived form Newtonian physics, for further understanding (modern physics), kindly refer to other resources. Thanks Philosophically, it all lies in your belief. Whether you call it an effect, or phenomenon, etc. Physics is not about wordy explanation, but simple, precise formula, presented mathematically and objectively. Distance, displacement, volume, length etc. are physical quantities. If you keep on asking on, you can have infinite questions like what is length, what is voume, what is distance?... I only know one thing, Physics is all about physical quantities, like Maths is all about numbers. No numbers, no maths ; no physical quantities, no physics. Physical quantities are abstract, they are described mathematically. it is not an object, nor it is an effect. It is a phenomenon, which happens on an object directly or indirectly. You measure and investigate the effect of gravity on objects like moon, earth,etc. Gravity is abstract, like distance. Only when I walk, you can know my walking distance. Only when you move near to the speed of light, you can measure its effect, so gravity is not about what is it philosophically, but its effect and changes. Asking what is gravity while not answering it in a scientific way is like asking why is there gravity? Simply put, why gravity exist?

You should have solved the problem with ease by simply using normal mathematics, bypassing logarithm. Does the question state that logarithm must be used? From post #3, simply add 0.5877(3) and 1.3010 for the upper part and 0.5877(3) minus 1.3010 for the bottom part. You get 10 to the power of [0.5877(3)+1.3010] divides by 10 to the power of [0.5877(3)-1.3010] Then, further simplify the equation and you get 10 to the power of {[0.5877(3)+1.3010]-[0.5877(3)-1.3010]} I can only help with high school maths. Sorry. The answer is approximately 400. Try and see.

My friend stopped subscribing from BBC Knowledge this February. This means I loss another source of Knowledge from the Scientific World. I used to borrow books from my friends nowadays. Why not purchasing them myself? Obviously, lack of money. An encyclopedia cost me at least RM 100 here in Malaysia. An ordinary science book, say Einstein Relatively Simple from one of our members, Ira Mark Egdall, here in the SFN, cost me RM 60. Something like 2 decades ago, a similar book would have cost RM 30-I borrowed one from my tuition teacher. You my argue such things are rare in the West as books there can be much cheaper. But in Malaysia, this is definitely not the case. We rely on Primary economic sectors- chief among them oil palm industry, rubber industry and petroleum/natural gas industries. These commodities heavily rely on market price. Sadly, we are incapable of dominating the market. Recently, WTI and Brent oil prices hit low and this has taken a toll on Malaysia`s economy. Moreover, 1st of April 2015, GST or Goods and Service Tax will start to be imposed on daily goods and luxury items. Unfortunately, my favourite-books aren`t on the exclusion list. Simply put, books are getting more expensive. Yet, GST isn`t going to be imposed on e-books. Why? Why books? Isn`t it the government`s duty to promote people studying? Didn`t the government know harmful rays from computer/smartphone/tablet screen will harm our little eyes? And what about student? Shouldn`t there be some coupons or discount for students? Weaken Malaysian Ringgit, Plummeting Crude Oil Prices... a multitude of factors are bringing the storm of hell to Malaysia. We heavily rely on imported goods. Books in libraries are outdated, torn and quite far from my home. Now, I can only rely on newspaper, be it English or Chinese, to catch up with science news. That is not enough, definitely. I don`t used to turn out my computer, and I have no smartphone and tablet. You may come out with other solutions-like requesting school to subscribe science magazines in a group (usually more than 15). But the problem is how many people will buy them? Does it worth the purchase? Malaysia lacks the facility and infrastructure to conduct scientific experiments, despite its strategic location and rich heritages-ancient tropical rainforest for biology, spacecraft launching with lesser fuel (because it is on the equator) for space exploration. Malaysia has plenty of land, but most of them are used for cash crop plantations. Can we build a Knowledge society when we are fogged by racial and religious issues (in Malaysia)? Can anyone advise a 16-year-old where to attain new scientific knowledge "in the midst of turmoil and hardships (economically)"? Can anyone comment on this please? Thanks.

Why not? I am living in Penang, though it is close to the equator, it is still considered as the northern part/hemisphere. You see the moon virtually anywhere around the globe, except places around the poles, where it happens occasionally1. The Moon definitely enters the North part of the sky. You can check you astronomy encyclopedia or any star charts. Extra1: http://curious.astro.cornell.edu/question.php?number=777 You can check the transit/rise and set time for the Moon from: http://www.usno.navy.mil/USNO/astronomical-applications/data-services

Jupiter`s formation during the early infant years of our solar system is indeed the cause of prevention of terrestrial planets after Mars. Strong Jovian gravitational perturbation results in remnants of protoplanetary disc forming asteroid belt. Here is an article, somewhat old, but still informative. Maybe it will answer your question. http://www-personal.umich.edu/~equintan/Other_Publications/Asteroid_Lissauer.pdf

No, no, no John. You are wrong. I don`t know how things really are in the UK. In Malaysia, things aren`t as simple as 1 mark for 1 criterion. Some mistakes are considered minor and half mark is deducted. Students usually take advantage of the "round off" rule to gain marks. For example, 0.5 marks is deducted for wrong spelling but it does not impede communication, so 30 becomes 29.5. But when you round off the figure, it becomes 30 again. Also, essays, like language, are subjective. In Malaysia, only wrong formats in formal essays like formal letter, CV, reports, articles etc. will be deducted marks. The open-ended essay I had written does not constrain the writing style. It is open, no format. So, in this case, the way you present your ideas, the sentence structures, gain more weightage. For instance, a person writes "The US is different from the UK" will gain less mark compared to a person who writes" The US differs from the UK in quite a number of aspects". Why? Because we used to write and convey our ideas in the first form, it becomes a norm. Nothing sets you apart from the others. So, you gain less mark. This year, a new teacher will teach us, so my plan is to discuss with her, so as not to ensure she "goes crazy" with my "scientific" essay.

I supposed that most of you are well aware that I did quite well in my studies. However, there are some incidents and cases where I might make a mistake. Yet, somehow, a case happened last year was deeply etched in my mind. I would like you to help comment on this issue. Here is the story. Last year, I studied a lot of physics articles and books. I felt like my knowledge had increased a lot. All language subjects require you to write essays, either in the exam or daily practise. Usually, students have to choose the materials needed or maybe conduct some researches before entering the test venue. Most of the time, I will choose the materials that I know a lot- Physics, then only it is possible for me to write with minor to no flaws. And, also, given the fact no one in my school really likes Physics (they just take it as if it was just a subject, not their cup of tea) or studies quite a lot of it, Physics contents in my essay sets me apart from the others. I got Number 1 for my English essay competition last year. The title of the essay- My ambition. I drafted the contents quickly. I want to be a physicist, so I used a lot of scientific jargons while introducing my career. But this was not the case for Chinese language. I tried using the same way, adding stuffs that others, I supposed, won`t use. But I failed. This time, the background of the essay was about 60% similar to the English version. I also used Physics jargons and related them to the main topic/title. The essay was open-ended. The title consisted of just a few words of a sentence and you need to substitute your own words that is suitable to complete the title. The given title was "I love xxx the most". (Substitute xxx with any words, in this case, I used science) I drafted and started writing. The problem was its result. When my teacher returned the papers, she simply marked through it. She just put a "check" (the opposite of cross, x) behind every punctuation of the last sentence of a paragraph. Upon completing, she wrote the marks 18 out of 30 or 18/30 plus a circle around it. No lines, straight or wavy, indicating any errors ; no words and comment. The whole essay was merely filled with words of mine, "checks" and marks with circle. I am dissatisfied. I walked bravely to the front desk, inquiring reasons. Her words: "I am a (Chinese) language teacher. I don`t understand what you are writing, I am not a science teacher. I don`t understand, really." A huge let down. Really. I took the papers and reported her to the principal`s office a few days later. I questioned: "Is it my fault for not letting a teacher to understand technical jargons? She didn`t even mentioned it to be right or wrong. The teacher should be diligent enough to do her homework-look up those words in the internet or a dictionary, shouldn`t it?" Also, I told quite a number of teachers of other subjects. Firstly, my English teacher. She told me to just ignore her. Maybe to her, this was just a minor case, an exception? Others advised me to talk to her, discuss directly with her. How is that possible? She hurt me in first place. Plus her mind was somewhat conservative. She kept telling us Buddhism philosophies in her classes. I found another unorthodox phenomenon. When you write about essays that require you to elaborate the benefits of reading, stating the point "study Buddhism books can make you feel peace deep in your heart and spirits" instead of just writing "read more reading materials like newspaper, books and magazines can enhance your knowledge" can result in a mark or two higher than the average. While including scientific points may result in a mark or two lower than the average. Some of you may argue this is just a myth or feelings but it did happen in my essays-I have proofs. This year, I supposed I am going to "inform" my teacher about this rare case before indulging in my scientific world. Any comments? Thank you.

Force. Recall the formula for work done. W=Fs, whereas W=work done, F=nett force, s=displacement The fabric? I supposed you are talking about the space-time continuum. First of all, work done can be defined in many context. Work done against gravity is just one manifestation of work done. For instance, say I move a wooden block with a force of 3N across a smooth floor (with negligible friction and air resistance) for 1m, based on the formula W=Fs, my work done is 3N m, or simply 3 Joule. The wooden block and I are all on the Earth, within its gravitational influence. But recall that displacement is distance in a particular direction (of the nett force). So I push the block forward, my direction is to the right (from you view as a spectator standing right beside me) Only the distance I moved to the right will be considered, independent of Earth gravity. For overcoming gravitational force, the direction of nett force is upwards, therefore, only the vertical distance is considered. I would suggest you so as not to use the word fabric anymore. It is quite misleading. In fact, Einstein`s General Relativity say nothing about space-time as a fabric. Mordred, one of the members in scieceforums.net, advised us to not thinking of space-time as a fabric. he emphasizes it many times. Refer: Post 16, "Space is not a fabric" http://www.scienceforums.net/topic/86180-vacuum-energy-universes-within-universes/ This is a better desrciption. Post 9, http://www.scienceforums.net/topic/83690-what-is-space/?hl=fabric Entropy is related to second law of thermodynamics. it is something like a measure of the complexity of the order of the universe and nature. Imagine you have a ball and a transparent empty can. You throw the ball into the can, it settled down after a while, you shake the can, it settled down after a while. Will the ball settled at the same place exactly as the previous one. It is almost impossible, though theoretically possible. Entropy increase along with time. Things become disordered after time. For Big Bang, i don`t really know what you mean. Big Bang is a too general term. You can state the exact epoch for a better explanation, e.g. First 3 Minutes etc. Some scientists proposed that Big Bang start off with a quantum fluctuation. A sudden energy surge resulting in our current universe. I spent some time rereading your question. I roughly know what you are talking. you must be talking about dimesnions. Our "mother" universe is unstable in higher dimensions, so the universe "break down" into a four-dimension universe (our universe) and an unseen 6-dimension universe. The 6-dimesnion universe is too small to be observed. Here is how to relate it with energy. (based on my speculation on what you had typed) Imagine having a pencil positioned straight upright on a table. This is a state of balance, technically know as unstable equilibrium. This is almost impossible in real-life practice. But this is an equilibrium theoretically. The pencil will then fall onto the table to achieve neutral equilibrium. The universe is unstable in higher dimensions so it must go through quantum tunneling to lower energy state, which is 4-dimension. Does the above information help? If you delve further, you may encounter Kaluza-Klein Theory, Superstring Theory etc. They have something to do with higher dimension science.

First thing first, this question is actually a topic of electrochemistry, so it must be posted in chemistry section of this forum. Make sure that you know how to differentiate chemistry and physics. Your post will be moved to chemistry soon. Lets start with atoms. An atom is composed of protons, neutrons and electrons. Normally, they are confined together. Since protons are positively-charged and electrons are negatively-charged, they will attract each other, posing an electromagnetic force between them. Neutrons are neutral. When we say an atom is ionized, electrons are stripped away from the atom, the atom is said to be be charged and known as an ion. Ion forms because there is an imbalance net charge. Protons wouldn`t be ionized, so as electrons. They carried charged, so they won`t be further "ionized". Protons don`t contain electrons. So, both your last 2 questions are invalid. Electrolytes are charge carrier. They carry charge. They become ionized in certain solvents. So, they can transport charges. Try to grasp the basic chemistry before delving further. This post may help: http://www.scienceforums.net/topic/86381-basics-of-batteries/ Water is a universal solvent. Oil is an organic solvent/Polar solvent. That`s why oil can reduce stains. Electrons here means free electrons. Electrolytes can be both positively and negatively ionized, depends on the nature of the electrolyte itself. Try to read the electrochemistry section of the wikipedia Electrolyte

The universe is still expanding (and accelerating). Since the universe is borned 13.7 billion years ago, the furthest point we can see must be 13.7 billion light years away. But since space is expanding, the proper distance would be about 47 billion light years away.

It is 380,000 years. (a typing error?)

I am also in high school. To study space and astronomy, be sure to have a good understanding about Modern Physics. My personal experience tells me classical physics that you learn in high school isn`t enough. The 2 main physics are Relativity and Quantum Mechanics. For relativity, I would recommend Ira Mark Egdall`s Einstein`s Relatively Simple. Mr. Egdall is one of the members in this forum. His book is very suitable for undergraduates and those who are interested in relativity but never though possible. It is about RM 62 in Malaysia. For quantum mechanics, I offer no suggestion becuase I haven`t really found any good book about QM. Nevertheless, you can still attain knowledge by reading through many articles about QM in the web or several books, like Stephen Hawking`s The Universe In A Nutshell. Modern physics do rely on equations/maths, you can never get away from them, but some of them can be quite simple. I would recommend studying relativity first. Its equations are quite easily understood, compared to QM. I do have a collections of papers and ebooks about modern astronomy and physics. Feel free to request them if you want. Astrochemistry and astrobiology are important too. But they are not "attracting" the limelight, unless there are some new or stunning discoveries. One famous example is the landing of Philae from Rosetta, an esa probe, on the comet 67P. Scientists strongly believe that comets and other planetary remnants are keys to discovering the origin of lives and the evolution of the early solar system. Have you studied calculus? A good ebook brings you through the QM world from scratch is Richard Feynman`s Lectures on Physics http://www.feynmanlectures.info/ http://www.feynmanlectures.caltech.edu/ I would recommend encyclopedias too. I have 4 astronomy encyclopedias. If you are living in Europe-America, I believe that you can access encyclopedias easily from library or buy them from bookstores. Encyclopedias are key to mastering astronomy. One of them is The Illustrated Atlas of The Universe, which is one of my collections.

Hello. You misunderstand quite a lot here. Now, there are 2 conditions. One is on Earth, another is on the Sun, more presicely, its core. On Earth, we can have a wide range of plasma, from very cold ones to very hot ones. http://en.wikipedia.org/wiki/Plasma_%28physics%29#mediaviewer/File:Plasma_scaling.svg But, for nuclear fusion to happen, we only need the hot plasma. You can never expect cold plasma to fuse. How hot? As long as it is above the critical ignition point. Refer: http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html And don`t forget immense pressure too. Now, on Earth, it is very unlikely to find a place that can have such immense pressure, not even earth`s core, so scientists on earth that want to conduct nuclear fusion just have to go all the way up to the temperature. Low pressure means an even higher temperature, as long as the ions are closer than 1 * 10-15 m. This is the coulomb barrier. Any distance longer than that value will cause fusion fail. So, in conlusion there are different temperature requirements for different conditions. Unlike Sun`s core, we don`t have that much pressure. Secondly, atoms won`t fuse. Ions do. The Sun has no gas, only plasma. They don`t re-associate. After 3000K, the ions, on average, still haven`t break the coulomb barrier, so temperature continue to rise, if the pressure is intense, this help to achieve fusion in much lower temperature. Then, in appreciable temperature, fusion begins. since we say plasma and ions, this means electrons don`t involve in such reactions. That`s why atoms cannot fuse becuase electrons are still bounded to them via electromagnetic force. Famous examples include Proton-proton fusion, CNO Cycle (for heavier stars) and tri-alpha process. Remember that in those reactions, electrons aren`t involve. http://en.wikipedia.org/wiki/Nuclear_fusion Thus, the usage of atoms here is wrong. Thirdly, in the begining of the universe, nuclear fusion does occur rampantly. It starts at 0.01s after Big Bang and slows down after the First Three Minutes. http://en.wikipedia.org/wiki/Chronology_of_the_universe#mediaviewer/File:History_of_the_Universe.svg During that epoch, lighter elements like hydrogen, helium, and minor traces of lithium and berrylium are thought to be formed. This is nucleosynthesis. Later only heavier elements form in stars core and continue to be recycled during supernovae nuclesynthesis. Thus, it happens. Nuclear fusion of lighter elements do occur in wide scale and the effect is observable today. Our observable universe today is about 3 quarters hydrogen and one quarter helium with minor traces of other elements. Addendum; on earth, nuclear fusions are carried out in several places and the progress is quite slow compared to nuclear fission due to technical issues. Don`t confuse nuclear fusion on earth over nuclear fusion in the Sun`s core.

Maybe this can help? http://en.wikipedia.org/wiki/Limiting_reagent

Do you know what is a salt bridge? The key to your answer is in the salt bridge. I am nowhere near a chemistry expert. Sorry. Well, In a simple Daniell cell, the copper is the positive terminal-anode, zinc is the negative terminal-cathode Do not confuse with anion and cation. Anode attracts anion. Recall electrolysis of water, you connect anode to the terminal in which in the end oxygen is collected. Oxygen gas is formed from O2-. 2 O2- froms one oxygen molecule-O2. Oxygen is negative-anion, the terminal is positive-anode. The situation is the reverse in hydrogen terminal, whereas hydrogen is positive in ion H+-cation and the terminal is negative-cathode. After realising these principles, let`s start to investigate how a Daniell Cell works. Zinc is immersed in zinc sulphate solution, copper is immersed in copper(II) sulphate solution. A salt bridge contains inert ions or salt that does not react with the electrolyte. Examples are NaCl, KCl, KNO3, NH4Cl and dilute H2SO4 A simple salt bridge can be made by immersing a piece of filter paper in sulphuric acid or in a salt solution. Functions of salt bridge: To allow the flow of ions so that the circuit is completed. To prevent the 2 aqueous solutions from mixing. This will prevent displacement reaction between a more electropositive metal and the salt solution of the less electropositive metal from taking place. The reaction: Zinc reacts directly with copper(II) sulphate solution in a displacement reaction. Zn + CuSO4 produce ZnSO4 + Cu As a result, the zinc metal will be coated by a layer of copper metal. The electric current decreases rapidly. The salt bridge prevents the zinc from reacting directly with the copper(II) sulphate solution. The final reaction: At the negative terminal, cathode: Zn becomes Zn2+ + 2e- At the positive terminal, anode: Cu2+ + 2e- becomes Cu Overall reaction of cell: Zn + Cu2+ becomes Zn2+ + Cu The copper will become thicker(mass increase) the zinc becomes thinner(mass decrease) The concentrationof the blue copper sulphate solution becomes paler and the concentration of zinc sulphate solution increases. The key is the salt bridge, which is inert(means lazy and less reactive. Have you heard of inert gases? Neon, Argon, Krypton, Xenon and Radon which are octets/duplets achieve stability in terms of electronic configuration, thus stable and less reactive) don`t react with either solutions and metals. The are just transporter/medium of ions to complete the circuit. Hope that this is clear enough.

If you say free-fall, you only take gravity into account. In earth, freefall can only occur in vacuum that is empty(actually, it isn`t empty, there are virtual particles). Yes, if an object falls, gravity acts on it at first. As it speeds through air, it rubs with air and friction, which we call air resistance, build up. The air resistance oppose the movement of the moving object, that`s why when an object falls, its gravitational acceleration will eventually become less, until it reach terminal velocity, or simply touches ground if the falling distance is short enough. Air resistance depends on the speed or velocity of the moving object, unlike friction. The faster you move, the greater the air resistance. In aerodynamics, air resistance is also (and usually) known as drag, D. Air resistance also depends on surface area. The larger the exposed surface area, the greater the air resistance. If you want to experience air resistance in simulation on computer, try Orbiter 2010. It teaches you about aerodynamics. orbit.medphys.ucl.ac.uk

Quantum theory/Quantum mechanics is a theory first based on the Planck Light Hypothesis. Max Planck proposed that light comes in discrete packets of energy known as quanta. This idea is further extended by Werner Heisenberg in 1937 in his Heisenberg`s Uncertainty Principle. Basic formula is as follows: Uncertainty of position times/multiplies uncertainty of speed times mass is greater than or equal to planck constant divides by 2 whereas planck constant is greater than 0. This is basic knowledge. Another famous equation is E=hv whereas E is energy, h is planck constant and v is an object`s frequency. This equation links an object`s, usually a particle, energy to its frequency. Thus, particle-wave duality exist. This means you can treat an object as both particle and wave. But for macroscopic objects like human, the wave is too small. A cat, for instance, if drawn to a size of a solar system, it`s wavelength would be no longer than an atom in it. You should have known wave-particle duality from the double-slit experiment. Here are some basic links and videos to be shared:(one of them includes an explanation about the double slit experiment) These links are from Dr. Tom Swanson`s blogs and other members in this forum. Here`s That Cat Again by swansont- Animation that is informative and suitable for newcomers http://ed.ted.com/lessons/schrodinger-s-cat-a-thought-experiment-in-quantum-mechanics-chad-orzel http://ed.ted.com/lessons/einstein-s-brilliant-mistake-entangled-states-chad-orzel http://ed.ted.com/lessons/what-is-the-heisenberg-uncertainty-principle-chad-orzel Try volume 1 in Feynman`s Lecture of Physics http://www.feynmanlectures.info/ http://www.feynmanlectures.caltech.edu/ How old are you? Quantum mechanics isn`t being taught in secondary school. Only classical physics is being taught in secondary school.

You mean 1. Fuel are stored in storage tanks; 2. Pipes lead them to the combustion chamber; 3. On the way, they are placed near the engine, so the engine takes advantage of the flow of cold liquid O and H to lower its own temperature; 4. The pipes end at the combustion chamber, injecting fuels into chamber for burning; 5. Gas escape from nozzle; 6. The process continues until no more fuel is left?

1. No, I disagree. Rockets aren`t just huge tanks and nothing more than that. They must have load bays, engines etc. 2. I roughly speculate why. Is it becuase both O and H in liquid form/phase has very low temperature, since they exist as gas in room temperature, therefore they must have lower temperature in liquid phase. The tenperature is close to Absolute zero, something like -273.15-250= 23.15 degree Celcius difference. 3. No, sorry, I don`t understand. I thought liquid O and H flows directly from the storage tank to the engine/combustion chamber. They are always cold when stored, aren`t they? Why cooling down the engine? The fuels are used to burn to produce enough momentum to push the rocket from thel launch pad, but not to simply cool the engine down, aren`t they? 4. What is f.e.? Sorry, I don`t understand shorthand writings. Thanks.

I am sure most of you are informed that the Antares incident in Wallops Flight Facility in Virginia that happened 6:22 p.m. EDT. I am wondering why no one start a topic about this sad incident. It appears to be very serious. Usually, when any rocket fails during launch, newspaper in Malaysia will only show the news as a small paragraph in some small column that isn`t easily identified. But this time, it appears to be a full page with detailed explanation. To prevent this thread to be regarded as off topic, I posted a link-related conference by NASA. There are many links if you Google NASA or Antares in the News section. The main reason I posted this topic is to understand more about why (this) rocket may fail during launch, I mean what are the possibilities/causes that may arise in this incident. I know there are experts in space engineering in this forum. Can anyone please help to increase my knowledge?

Congratulations! But this can never happen in Malaysia. I am sorry for my ignorance. I thought he didn`t do well in his school exam, except maths and physics. He failed in French and Chemistry, sunjects he didn`t care to learn. His parent bought books for him? I just only know this now upon seeing your post. I think you mean school physics and maths curriculum, not all subjects.

I think he means mass of the particle, since he also uses charge before in the phrase 'acceleration of the charge'

Is this question dealing with frame of references? It seems like they can be 2 point of view, the ground observer and the passanger on the train. You mean accelerating downwards becuase of gravity or accelerating forwards for a brief moment due to addition of velocity by the accelerating train before dropping towards the floor?

Hello Egdall, I bought your book Einstein`s Relatively Simple a few months ago. Thanks for explaining relativity in such a clear and compelling way such that a 15-year-old can understand. Well, I think you are right. Singularity does not exist physically, it is just a mathematical trick. The equation falls at that point. We need new physics. Recently, I read Hawking`s The Universe In a Nutshell, an old 2001 book. He suggests we can look at the phenomena from another perspective. We can assume black hole as a p-membrane and the particle that falls into the black hole as a closed string. The closed string strikes the p-memberane and the wave of the membrane focus and reemit a closed string, which is analogised as to a particle emitted from the black hole as Hawking`s Radiation.

Fuzzwood, thanks for introducing me a new type of quasiparticle, polaron.