Misconceptions of E=MC^2

No, it isn't just a number. There are units involved too. Look at this common equation:speed = distance/timeThey aren't numbers. Distance could have the unit of metres. Time could measured in seconds. If they are measured that way we might say that the unit of speed is therefore "metres per second". Not only do the numbers balance, but so do the units.In everyday life we measure distance in miles and time in hours and we measure speed in mph. It is rare in physics to find equations that are 'just numbers' but they possess units too (since they measure real things). Permutations of an equation are not capable of a reaction. They are just different ways of expressing a certain relationship. If you want to know what c is you measure e and m and you can infer c. If you want to know what e is, you measure m and c, and if you want to know what m is...John has a brother called Mark. Their father is called Mike.ORMike has two sons, John and Mark: his sons share the same mother.They are two different ways of describing the same relationship. 3 is the same as 2+1. 2 is the same as 3-1. The same relationship, expressed differently. You can perform an experiment to get e, m and c. You can then plug those values into any permutation of the equation and confirm whether the relationship is true.

In mathematics, they are the same thing. A formula that you might be thinking of (in the sense of reactions) is a chemical formula. A chemical formula is quite different than a mathematical equation in format.A chemical reaction might look like several chemical formula like:N₂ + 3 H₂ ’ 2 NH₃Nuclear reactions are trickier still.

No, they describe a relationship between certain things in nature (energy, mass, the speed of light, force, acceleration etc etc). No, the values of e and m depend on what we're looking at. If we are looking at an object of 1kg, then the m is 1kg. If we are looking at an object of 10kg then the m is 10kg.If something has an energy of 1million joules, then e=1MJ - if it has an energy of 10million joules, then e=10MJ. No, there are no chemical reactions present. Heh, don't worry about it - it is a selfish endeavour. There is nothing better to revise these things than to explain them to someone who doesn't understand them as well as yourself. Some people have short patience with people that make declarations that aren't true with a seeming confidence. You might not intend it, but some of your posts give off such an impression. I prefer to give the benefit of the doubt:- a lot of communication can be lost through the written word and it can take experience of the misunderstandings that can arise through the gap between what is said and what is meant. This is true. I think a good example of a misconception, which I might have held until this thread, was that nuclear reactions and chemical reactions aren't different in the energy/mass equivalence stakes. I hadn't really thought on it before - but I don't mind admitting I might have made a boo-boo had someone quizzed me on it before reading cavediver's earlier post.

Elements, from the periodic table. Good assumption. Yes, it is a way of producing ammonia. No. It is a way of describing the relationship between a substance's mass and its energy. There is usually more to them than given in these simple formulae. E=MC^{^2} doesn't describe a reaction, it describes a relationship.

Same kind of thing. A reaction basically is a chain of events. There are no chains of events in e=mc^{^2}. I imagine many people, if not all do this from time to time. When you do, you can expect to be told in no uncertain terms. It can be a good thing - don't worry too much about it though, it's not usually meant to be personal. Where it is, hey - how personal can strangers get?

The amount of energy that something has is proportional to its mass. Using standard units (and in simple terms), the amount of energy something has is equal to the product of its mass and a constant that is equal to the speed of light squared. No, they just represent the way mass and energy are related. It is itself a prediction of Einstein's theory of relativity. The prediction is that mass and energy will be related in the fashion described by the equation.Edited by Modulous, : No reason given.

Sure, you can predict what e will be given m and c. But I don't Heinrik meant that. If you read back through some of his comments he seems to still be thinking of e=mc^{^2} as something akin to a physical reaction like combustion. He seems to be wondering if one permutation of the equation does represent a physical reaction. Like maybe, e=mc^{^2} is sometimes thought of as the formula that describes a nuclear explosion or whatever, or it represents a reaction whereby pure energy becomes mass, or mass can be converted into the speed of light squared or some such strangeness.

Yes. Experiments have been performed that measure the mass of something and its energy and the relationship between them is as described in the equation.

No mass is lost at all (in total)- mass and energy are two sides of the same coin. The piece of matter that had the atoms now has less mass since some of its energy has been put to usually been put to work and has now dissipated.The energy doesn't immediately become matter. The energy does have an associated mass. Matter and mass are different words with different meanings, an easy mistake to make though.

I don't think I did. I try and avoid doing this kind of thing, because I know I'll be called on it by any number of the more knowledgeable people around here. Two reasons spring to mind. I tend to word things that I am not sure of in a limited fashion, with disclaimers and tentativity. I think it is better to avoid insisting I am right when people I judge more knowledgeable than myself are telling me I'm wrong. Either that, or they thought you were more educated that you are. When you said 'Year 12 science", I took that to mean a level of maths equivalent to my own. That includes up to doing calculus on trigonometric functions. In my maths education, I also had to learn the mathematics of basic physics (Newtonian mechanics).With that in mind, I tried to speak to this level, I suspect others were doing likewise.I don't think anyone was trying to blind you with science, and if that was the effect it was almost certainly unintentional. When in doubt, I find it best to assume others have nothing but the best of intentions rather than the worst. I find my time here much more enjoyable as a result.

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Anyway, you're free to disagree. This probably comes under Admin's warning above and in light of that, it's probably wise to leave it there.Edited by Modulous, : No reason given.