The Real Meaning of E=mc²

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Recommends Weezy · 2015-11 · Physics Stack Exchange · on “What makes energy content of a body harder to accelerate it?”

There was a video on the YouTube's PBS Spacetime channel [this video] where the host, Matt O'Dowd, a PhD and a working physicist, explained the "Real meaning of $E=mc^2$ " by saying that even at the most microscopic level even the fundamental particles could be thought of as really a manifestation of binding energy of things that are bound together to create the particle. This only means that there is no such thing as mass and all of physics could be explained via the energy picture only. While I find this somewhat convincing I don't understand how this picture can explain why heavier things are harder to accelerate. What is it about a body that makes it harder to push if it has just more of ener

Recommends user87745 · 2016-06 · Physics Stack Exchange · on “Does $E=mc^2$ mean that an object with mass $m$ travels at the speed of light in empty space?”

[this video] "Mass $m$ can be converted to energy $mc^2$." is not a perfectly alright statement. Have a look at the video attached!

Recommends Geoff Canyon · 2016-08 · Physics Stack Exchange · on “Does potential energy in gravitational field increase mass?”

Yes. All energy contributes to the overall mass. PBS Space Time has a really clear video on this subject: The Real Meaning of E=mc² [this video] In the video, Gabe points out that Einstein originally wrote the equation as m = E/c², and describes how all energy has the property of mass, including potential energy. Edit to add: it's important to note (as is mentioned in the video) the potential energy of a particle within a system does not change the mass of the particle itself. Instead, it contributes to the mass of the system within which the particle has potential energy. Also note that a particle considered in isolation has no potential energy.

Recommends Geoff Canyon · 2016-08 · Physics Stack Exchange · on “Negative potential energy of gravity”

PBS Space Time has a really clear video on this subject: The Real Meaning of E=mc² [this video] In the video, Gabe points out that the mass of a Hydrogen atom is less than the sum of the masses of a free proton and electron, and that the mass of an oxygen molecule is less than the sum of the masses of two free oxygen atoms, in both cases because of negative potential energy. Gravitational attraction to the overall system would therefore be less. Note that this assumes some perfect way of changing the position of the objects within the system. For a counter-example, if a rock falls off a cliff on Earth, its potential energy is reduced, but other forms of energy result from that loss, in equal meas

Recommends Himanshu · 2020-10 · Physics Stack Exchange · on “Does mass really exist?”

In elementary physics, I have learned mass as the amount of matter (naively) and energy as the ability to do work. Now we know that they interchangeable by famous Einstein's equation: $$E=mc^2$$ It seems from here that they are interchangeable, but then I watched this video [this video] , which says, in a nutshell, that the mass actually never existed. We are actually measuring energy all along. Now there are some subtleties I'm facing through this concept. Why do I need the concept of mass now? Edit: In video, he says that at most deeper level particles -- like protons -- get their energy from quark potential energy. So that means at this level you don't have mass but energy. So can't we change

Recommends Tommy White · 2022-05 · Physics Stack Exchange · on “How to understand $E=mc^2$?”

It's very easy to understand $E=mc^2$ . All Einstein's very short paper on the subject, with the English translated title "Does The Inertia of a Body Depend on Its Energy Content?", sais is that $E=mc^2$ means is that the inertial mass of a body increases (or decreases) by the amount $m=E/c^2$ if its energy content increases (or decreases) by an amount $E$ . If that doesn't satisfy it, this legit video is very accessible: [this video] The Energy–momentum relation was established by Paul Dirac in 1928, but is fundamentally different than $E=mc^2$ . Those are two separate things. (I don't understand why other answers involve that to be honest.) Anyway, what's not so easy to understand is why it is

Recommends Zaza Orji · 2023-06 · Physics Stack Exchange · on “How can negative potential energy cause mass decrease?”

The mass of a hydrogen is less than its constituent parts(proton/electron). The explanation given for this is the following: [this video] For hydrogen, $m = m_{components} + m_{extra}$ where we can write $m_{extra} = E/c^2$ where $E$ is the PE and KE of the proton/electron interaction. It turns out while KE > 0, PE is much more < 0, so their sum becomes negative, so $m_{extra} < 0$ . What I have a difficulty to see is how PE can be negative. I know, if you treat that when proton and electron are infinity far away and we treat PE=0 for that case, then the more they get closer, PE decreases and becomes negative, but for our case, this seems to me no proof at all. I could just treat $PE=infinity$ wh

Recommends Ofek Gillon · 2024-06 · Physics Stack Exchange · on “Can electrons or protons due to fusion reduce in their individual mass?”

Your assumption is exactly what leads you to this incorrect conclusion. Einstein's $E=mc^2$ states that systems of particles gain/lose mass by means of gaining/losing energy. Meaning that the mass of a system is not only the sum of the mass of the composite particles but you also need to take into account the energy due to their interactions. Most of the time we don't notice this effect, because it's negligible: strong chemical reactions release energy in the order of $eV$ , which lowers the systems mass in about $10^{-6}$ to $ 10^{-5}$ the mass of an electron, which is on its own has only $10^{-5}$ to $10^{-4}$ of the mass of a simple chemical compound, meaning the change in mass in a chemi

Recommends mmesser314 · 2024-06 · Physics Stack Exchange · on “Why does binding energy of particles, which constitutes most of macroscopic mass, make them harder to accelerate?”

You might also ask how mass makes it hard to accelerate an object. It just does. And it is the same for how energy makes it hard to accelerate on object. You might take a look at this PBS Space Time video - The Real Meaning of E=mc² [this video] . It makes the point you already know that adding energy increases mass, or resistance to acceleration. But also that mass arises from energy. It also has a link to an English translation of Einstein's original short paper, Does the inertia of a body depend on its energy content? [LINK] , which also does not propose a mechanism.

Cites Peter Bourne · 2015-07 · Physics Stack Exchange · on “Does a ticking watch have more mass?”

In the video on YouTube, The Real Meaning of E=mc² | PBS| Space Time Studios [this video] , it claims that a ticking watch has more mass then a non ticking watch due to the intrinsic KE, PE and thermal energy of the watch's internal movements that manifests itself as part of the watch's mass. Is this correct ? To me there is something wrong with this argument, but I cannot put my finger on it.