When anyone who knows the least bit about physics is asked to recite an physics equation that pertains to a property of something, E=MC^2 is almost instantly suggested by the speaker. This beautiful equation is printed out onto t-shirts and worked into corny math jokes but do the printers of those t-shirts and the comedians of the math jokes really understand what E=MC^2 means?
In this week’s first every (yay!!!) installment of Science Weekly, I hope to be able to explain and help everyone reading this be able to put this simple-looking equation into context.
The equation was developed by Albert Einstein, who revealed the equation in the fourth section of a four part physics series in a german physics journal called Annalen der Physik, Einstein revealed his equation. In the equation, the variables represent energy (E,) the speed of light (c^2,) and mass (m.)
Now, to understand this equation, it is necessary to clear up a common misconception; the mass of an object is not the sum of the mass of its parts, it is actually a revision of that. The basic mass of an object is the sum of the mass of its parts + a little bit of mass that is added on based on reasons that can be seen in an analogy.
Say a runner is jogging at 8 miles/hour in a park and that runner has a clone that is in every way similar on an atomic level but is sitting still; the runner that is moving will have a greater mass. This is because the runner who is moving has kinetic energy and that kinetic energy that the runner has, adds onto the mass of his/her atoms to get the total of the mass of the moving runner. What e=mc^2 is saying is that that extra little bit of mass that is added on due to the energy of the runner is existent.
Now, you may be asking yourself right now, ‘well, if there were 2 giant scales and the runner who is moving is put up against the static runner, would there really be much of a difference, and if there is a difference, then why didn’t scientists figure this out before 1905?’ Well, this prompts me to show another equation that is the exact same as e=mc^2 but with rearranged variables: m=e/c^2. Now you can see that this new equation is solving for the (extra) mass of an object instead of the energy of that object. Please note that the speed of light squared is quite a giant number and most things have a fairly small amount of energy in relation to the speed of light, so when the amount of energy is divided by the speed of light, the amount of extra mass is quite a small amount, that’s why scientists couldn’t tell before 1905, (although Einstein didn’t figure this out with giant perfectly accurate scales.)
Sadly, there is just one little edit I would like to make now that you understand the general meaning of the equation. The equation m=e/c^2 or e=mc^2 is not solving just for the extra mass of an object, it is solving for the mass of that entire object. Think about it, literally everything has mass but everything has energy as well. Even down to the atomic level of the previously mentioned runner there is still the equation e=mc^2 playing its role, what I mean by this is that in the atoms, the protons and neutrons are spinning, so they have kinetic energy, which adds onto their mass, and that total mass of the atoms adds onto the total mass of the objects parts, which is added onto the extra energy produced by the interactions between those atoms. Thinking like this, mass and energy are closely interrelated; one might even say that energy is a component of mass.
This concludes this week’s Science Weekly blog post, I sincerely hope that you have enjoyed reading and that you have learned something new. If you liked this post, then stay tuned for more posts and if you didn’t, then, well, sorry. Thanks for reading and see you next week!
Some quick links and a video that I used to help me create this article are listed below:
https://www.britannica.com/science/E-mc2-equation
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