Why is Einstein’s E=MC2 such a big deal that everyone’s heard of it? How important was that discovery actually, is it like in the top 3 most important discoveries of all time or is it kind of overhyped?
In: 1393
Tl;Dr- This discovery is directly responsible for your smartphone, modern power plants, and nuclear holocaust, and it came about because Einstein was trying to settle a debate in the scientific community.
Hugely important and, to your point, often not discussed enough. So E=MC² represents the relationship between energy and mass. In the years before this theory, scientists agreed that when two or more substances underwent a change (we call this a system), the mass of all the inputs would equal the mass of all outputs – stuff wouldn’t just magically be created or destroyed. But agreeing to this had scientists differing on what the energy output of the system would be.
See, energy had been thought of as mechanically separate and unrelated to mass. The energy a system might output would be entirely dependent on the context of how much it had to begin with and how fast the change was and what the substances were. But in the years leading up to this theory, some scientists start realizing that if you give up on keeping mass the same through a change you can use a similar principle to ensure the energy of the inputs matched the energy output by the system. This meant you had to assume that objects inherently had energy in them.
Now along comes Einstein and he proposes that the relationship between energy and mass is a ratio, where the total energy of a system is equal to the mass times the speed of light squared. If this is true, then mass and energy are the same thing in different forms. Also, it means that everything around you has a LOT of pent up energy just by virtue of existing. And it’s starting to look like big, unstable atoms like Uranium might have A LOT OF ENERGY inside them.
So if you can find out how to convert one of those atoms into energy, a very small thing can give you a lifetime of electricity. And by extension of that, a big explosion if released all at once. Oops, now we have atom bombs.
So long story short, E=MC² gave us the bedrock for the last 100 years of technological advancement, nuclear power, the ability to destroy the planet, and some really cool tools for analyzing light.
Edit: Wow! Thanks for the upvotes! I see some of you confused about the relation between this and cell phones. When we make small computer chips, we need to worry about the boundaries of the circuit not being enough to contain the electrons at the speed in which they’re traveling. Instead of an electron colliding with the silicon boundaries of the circuit, it hits the silicon with such power that the silicon itself converts into energy. This let’s the electrons continue through the barrier and into neighboring circuits. This is called quantum tunneling, and you need to account for it when you want to pack hundreds of thousands of circuits in a black rectangle in someone’s pocket and have them be useful.
Edit2: Holy shit, thank you for the gold!
Edit3: Okay, one more because this question keeps getting asked – Why the C² bit? To understand that, we need to understand how Einstein is approaching this theory. Energy approaches the speed of light (C) the less mass the energized thing has. C is the ceiling for speed it seems like. So an easy way to define energy is by saying it’s equal to C when there’s no mass. But on the other hand, if the mass has any additional kinetic energy to it, we need to represent that too. Again, all energy approaches C the less mass it has. So we end up with Energy = Mass x Speed of Energy x Speed of Mass. A simple way to write this is to group the terms together, so we get E = MxCxC or E = MC².
Edit3.5: This is an ELI5 answer. It glosses over some stuff. There are critiques of my post below that are definitely valid, so I encourage you to discuss and learn more in the comments!
E=mc^2 (which is a simplified version of a larger equation, which is just one of many equations Einstein developed) is famous largely because it’s short enough to remember and simple enough that it can be explained to almost anyone. It’s the physics equivalent of a bumper sticker slogan—short, sweet, and to the point.
That particular equation is not tremendously *useful* all on its own, but it does point at the underlying truth that mass is just one form of energy, there is no fundamental distinction between the two. That said, E=mc^2 wasn’t a stand-alone discovery. It’s a small part of *special relativity,* a much larger framework that Albert Einstein developed to describe the fundamental physics of the universe. Special relativity turned our understanding of physics upside down, taking us from an era where we thought most of physics had been ironed out into a vast unknown where we had only scratched the surface, and where the fundamentals run against all our common-sense experience. With no exaggeration, relativity was the biggest, most revolutionary development in physics since Isaac Newton formulated his laws of motion and gravity in the 17^th century.
E=MC^(2) is only the easiest to understand of Einstein’s works – but some of his other works (specifically: Special and General Relativity) are probably more important.
Technically, none of what Einstein did were “discoveries”. Instead, he built on the work of other scientists, putting together their ideas in new ways that changed how people thought.
I could try to write out those two in an ELI5 way – or I could link an expert: [The Space Doctor’s Big Idea](https://www.newyorker.com/tech/annals-of-technology/the-space-doctors-big-idea-einstein-general-relativity) is Randal Munroe’s explanation of them. E=MC^(2) is a side effect of Special Relativity.
One of Einstein’s big contributions was “the speed of light is constant”. That little constant, c, was itself revolutionary. Why was that surprising? Imagine you throw a baseball pretty consistently at 50 mph. Next suppose you’re on a train that’s pulling away from the platform at 15 mph and you throw the ball in the direction the train is moving. To someone on the train with you, it will appear to move 50 mph. To someone on the platform, the ball is moving 65 mph.
But light is different. It has the same speed for all observers.
The general idea of “matter is just a special form of energy” was also revolutionary. And Einstein’s theories of relativity provide the reasoning for why the ratio between energy and mass is c^2.
E=MC2, and the theory of relativity that extends from it, is an extension, a furtherance of Newton’s Laws of Motion, at high speeds. If you plug in objects moving slowly into them, they become the Newtonian Laws.
What he discovered was, in its own way, as important. Many technologies central to our society today require understanding relativity and how speed and time interact to keep the speed of light constant, no matter what your speed is. Satellite GPS, for example. There are predictions Einstein made about black holes, based on that theory, that weren’t able to be measured until the 2000’s. And they were spot on.
Top 3 of all time? That’s a tall order. Agriculture and the wheel transformed society. Understanding of radio waves transformed society. Steam power transformed society (in fact, most power plants, from coal to nuclear, utilize steam power in their power generation). Einstein’s theory of relativity transformed society.
It’s hard to call it top 3. But it is in a class of rare discoveries that fundamentally transformed how humanity as a whole lives their lives. If you use Google maps, thank Einstein.
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You can change matter into energy and the other way around, knowing this.
However. c is the speed of light. And light moves extremely fast, so c is very big. c^2 is even bigger! So for even a tiny bit of mass, you get a huuuuuuuuuuge amount of energy.
That is for example why the sun works. It transform a tiny fraction of its mass into so much energy that everything can live here and be warm, and we only get a tony fraction of all the light from the sun!
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A lot of smart people have obviously already answered why Einstein’s work is important. But I think that’s not the only reason why E=mc² is so important, there’s also a cultural component to it. There are not many *modern* scientific theories and concepts that I can think of that can be neatly summarised by an easy equation that almost everyone can remember, recognise, and understand. It strikes a good balance between being complicated enough to “look smart” and being easy enough for the average person to remember, making it a perfect cultural “short hand” for science.
There are other formulae and their related discoveries that are also very important, but they’re not nearly as short and simple. Like [this one](http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgel2/maxw4.gif), whose complexity is illustrated by the fact I have to link an image of it because it can’t easily be displayed in markdown, whereas I can just type out E=mc² on my phone.
Why is Einstein’s E=MC2 such a big deal that everyone’s heard of it? How important was that discovery actually, is it like in the top 3 most important discoveries of all time or is it kind of overhyped?
In: 1393
Tl;Dr- This discovery is directly responsible for your smartphone, modern power plants, and nuclear holocaust, and it came about because Einstein was trying to settle a debate in the scientific community.
Hugely important and, to your point, often not discussed enough. So E=MC² represents the relationship between energy and mass. In the years before this theory, scientists agreed that when two or more substances underwent a change (we call this a system), the mass of all the inputs would equal the mass of all outputs – stuff wouldn’t just magically be created or destroyed. But agreeing to this had scientists differing on what the energy output of the system would be.
See, energy had been thought of as mechanically separate and unrelated to mass. The energy a system might output would be entirely dependent on the context of how much it had to begin with and how fast the change was and what the substances were. But in the years leading up to this theory, some scientists start realizing that if you give up on keeping mass the same through a change you can use a similar principle to ensure the energy of the inputs matched the energy output by the system. This meant you had to assume that objects inherently had energy in them.
Now along comes Einstein and he proposes that the relationship between energy and mass is a ratio, where the total energy of a system is equal to the mass times the speed of light squared. If this is true, then mass and energy are the same thing in different forms. Also, it means that everything around you has a LOT of pent up energy just by virtue of existing. And it’s starting to look like big, unstable atoms like Uranium might have A LOT OF ENERGY inside them.
So if you can find out how to convert one of those atoms into energy, a very small thing can give you a lifetime of electricity. And by extension of that, a big explosion if released all at once. Oops, now we have atom bombs.
So long story short, E=MC² gave us the bedrock for the last 100 years of technological advancement, nuclear power, the ability to destroy the planet, and some really cool tools for analyzing light.
Edit: Wow! Thanks for the upvotes! I see some of you confused about the relation between this and cell phones. When we make small computer chips, we need to worry about the boundaries of the circuit not being enough to contain the electrons at the speed in which they’re traveling. Instead of an electron colliding with the silicon boundaries of the circuit, it hits the silicon with such power that the silicon itself converts into energy. This let’s the electrons continue through the barrier and into neighboring circuits. This is called quantum tunneling, and you need to account for it when you want to pack hundreds of thousands of circuits in a black rectangle in someone’s pocket and have them be useful.
Edit2: Holy shit, thank you for the gold!
Edit3: Okay, one more because this question keeps getting asked – Why the C² bit? To understand that, we need to understand how Einstein is approaching this theory. Energy approaches the speed of light (C) the less mass the energized thing has. C is the ceiling for speed it seems like. So an easy way to define energy is by saying it’s equal to C when there’s no mass. But on the other hand, if the mass has any additional kinetic energy to it, we need to represent that too. Again, all energy approaches C the less mass it has. So we end up with Energy = Mass x Speed of Energy x Speed of Mass. A simple way to write this is to group the terms together, so we get E = MxCxC or E = MC².
Edit3.5: This is an ELI5 answer. It glosses over some stuff. There are critiques of my post below that are definitely valid, so I encourage you to discuss and learn more in the comments!
E=mc^2 (which is a simplified version of a larger equation, which is just one of many equations Einstein developed) is famous largely because it’s short enough to remember and simple enough that it can be explained to almost anyone. It’s the physics equivalent of a bumper sticker slogan—short, sweet, and to the point.
That particular equation is not tremendously *useful* all on its own, but it does point at the underlying truth that mass is just one form of energy, there is no fundamental distinction between the two. That said, E=mc^2 wasn’t a stand-alone discovery. It’s a small part of *special relativity,* a much larger framework that Albert Einstein developed to describe the fundamental physics of the universe. Special relativity turned our understanding of physics upside down, taking us from an era where we thought most of physics had been ironed out into a vast unknown where we had only scratched the surface, and where the fundamentals run against all our common-sense experience. With no exaggeration, relativity was the biggest, most revolutionary development in physics since Isaac Newton formulated his laws of motion and gravity in the 17^th century.
E=MC^(2) is only the easiest to understand of Einstein’s works – but some of his other works (specifically: Special and General Relativity) are probably more important.
Technically, none of what Einstein did were “discoveries”. Instead, he built on the work of other scientists, putting together their ideas in new ways that changed how people thought.
I could try to write out those two in an ELI5 way – or I could link an expert: [The Space Doctor’s Big Idea](https://www.newyorker.com/tech/annals-of-technology/the-space-doctors-big-idea-einstein-general-relativity) is Randal Munroe’s explanation of them. E=MC^(2) is a side effect of Special Relativity.
One of Einstein’s big contributions was “the speed of light is constant”. That little constant, c, was itself revolutionary. Why was that surprising? Imagine you throw a baseball pretty consistently at 50 mph. Next suppose you’re on a train that’s pulling away from the platform at 15 mph and you throw the ball in the direction the train is moving. To someone on the train with you, it will appear to move 50 mph. To someone on the platform, the ball is moving 65 mph.
But light is different. It has the same speed for all observers.
The general idea of “matter is just a special form of energy” was also revolutionary. And Einstein’s theories of relativity provide the reasoning for why the ratio between energy and mass is c^2.
E=MC2, and the theory of relativity that extends from it, is an extension, a furtherance of Newton’s Laws of Motion, at high speeds. If you plug in objects moving slowly into them, they become the Newtonian Laws.
What he discovered was, in its own way, as important. Many technologies central to our society today require understanding relativity and how speed and time interact to keep the speed of light constant, no matter what your speed is. Satellite GPS, for example. There are predictions Einstein made about black holes, based on that theory, that weren’t able to be measured until the 2000’s. And they were spot on.
Top 3 of all time? That’s a tall order. Agriculture and the wheel transformed society. Understanding of radio waves transformed society. Steam power transformed society (in fact, most power plants, from coal to nuclear, utilize steam power in their power generation). Einstein’s theory of relativity transformed society.
It’s hard to call it top 3. But it is in a class of rare discoveries that fundamentally transformed how humanity as a whole lives their lives. If you use Google maps, thank Einstein.
[removed]
You can change matter into energy and the other way around, knowing this.
However. c is the speed of light. And light moves extremely fast, so c is very big. c^2 is even bigger! So for even a tiny bit of mass, you get a huuuuuuuuuuge amount of energy.
That is for example why the sun works. It transform a tiny fraction of its mass into so much energy that everything can live here and be warm, and we only get a tony fraction of all the light from the sun!
[removed]
[removed]
A lot of smart people have obviously already answered why Einstein’s work is important. But I think that’s not the only reason why E=mc² is so important, there’s also a cultural component to it. There are not many *modern* scientific theories and concepts that I can think of that can be neatly summarised by an easy equation that almost everyone can remember, recognise, and understand. It strikes a good balance between being complicated enough to “look smart” and being easy enough for the average person to remember, making it a perfect cultural “short hand” for science.
There are other formulae and their related discoveries that are also very important, but they’re not nearly as short and simple. Like [this one](http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgel2/maxw4.gif), whose complexity is illustrated by the fact I have to link an image of it because it can’t easily be displayed in markdown, whereas I can just type out E=mc² on my phone.
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