A Fun Way of Understanding E=mc2 - Universe Today
E = mc2. It's the world's most famous equation, but what does it really mean? On the most basic level, the equation says that energy and mass (matter) are. e=mc2 Ask people to think of an equation, and, likely as not, E = mc2 will On the most basic level, the equation says that energy and mass (matter) "His bigger equation plays an enormous part in our understanding of how. Alok Jha: Albert Einstein's famous equation E=mc2 for the first time connected The relationship between energy and mass came out of another of the amount of energy released is big and the reason why is obvious when.
So the speed of light squared is the conversion factor that decides just how much energy lies captured within a walnut or any other chunk of matter. And because the speed of light squared is a huge number—,,, in units of mph—the amount of energy bound up into even the smallest mass is truly mind-boggling see The Power of Tiny Things.
Of course, intuitively understanding that energy and matter are essentially one, as well as why and how so much energy can be wrapped up in even minute bits of matter, is another thing.
But I hope that you, like I, now have a basic comprehension with which to appreciate the equation's prodigious influence. Energy in a nutshell: Though it hardly looks full of pep, a simple walnut has enough potential energy locked within it to power a city. Einstein himself suspected this even as he devised the equation. Einstein believed that radium was constantly converting part of its mass to energy exactly as his equation specified. He was eventually proved right.E = mc2 energy mass relationship hindi
Today we know radioactivity to be a property possessed by some unstable elements, such as uranium, or isotopes, such as carbon 14, of spontaneously emitting energetic particles as their atomic nuclei disintegrate. They are metamorphosing mass into energy in direct accordance with Einstein's equation.
We take advantage of that realization today in many technologies. Radiocarbon dating, which archeologists use to date ancient material, is yet another application of the formula.
Every time a patient undergoes a positron emission tomography, or PET, scan, she is "paying direct homage to Einstein's insight," Jim Gates says. Space travel in the distant future may also rely on such radiation-derived power. Photons streaming out from the sun and other stars hold energy that in the vacuum of space can theoretically be harnessed to propel a spaceship. Sunk deep in the ice, it will detect the eerie blue light, known as Cherenkov radiation, that is given off by neutrinos.
Neutrinos are subatomic particles so lacking in mass that they pass straight through the Earth unscathed. Two photons not moving in the same direction comprise an inertial frame where the combined energy is smallest, but not zero.
This is called the center of mass frame or the center of momentum frame; these terms are almost synonyms the center of mass frame is the special case of a center of momentum frame where the center of mass is put at the origin. The most that chasing a pair of photons can accomplish to decrease their energy is to put the observer in a frame where the photons have equal energy and are moving directly away from each other. In this frame, the observer is now moving in the same direction and speed as the center of mass of the two photons.
E=mc2: Einstein's equation that gave birth to the atom bomb
The total momentum of the photons is now zero, since their momenta are equal and opposite. In this frame the two photons, as a system, have a mass equal to their total energy divided by c2. This mass is called the invariant mass of the pair of photons together. It is the smallest mass and energy the system may be seen to have, by any observer. It is only the invariant mass of a two-photon system that can be used to make a single particle with the same rest mass.
NOVA | Einstein's Big Idea | Library Resource Kit: E = mc2 Explained | PBS
If the photons are formed by the collision of a particle and an antiparticle, the invariant mass is the same as the total energy of the particle and antiparticle their rest energy plus the kinetic energyin the center of mass frame, where they automatically move in equal and opposite directions since they have equal momentum in this frame. If the photons are formed by the disintegration of a single particle with a well-defined rest mass, like the neutral pionthe invariant mass of the photons is equal to rest mass of the pion.
In this case, the center of mass frame for the pion is just the frame where the pion is at rest, and the center of mass does not change after it disintegrates into two photons. After the two photons are formed, their center of mass is still moving the same way the pion did, and their total energy in this frame adds up to the mass energy of the pion.
Thus, by calculating the invariant mass of pairs of photons in a particle detector, pairs can be identified that were probably produced by pion disintegration. A similar calculation illustrates that the invariant mass of systems is conserved, even when massive particles particles with rest mass within the system are converted to massless particles such as photons.
In such cases, the photons contribute invariant mass to the system, even though they individually have no invariant mass or rest mass.
Thus, an electron and positron each of which has rest mass may undergo annihilation with each other to produce two photons, each of which is massless has no rest mass. However, in such circumstances, no system mass is lost.
Instead, the system of both photons moving away from each other has an invariant mass, which acts like a rest mass for any system in which the photons are trapped, or that can be weighed. Thus, not only the quantity of relativistic mass, but also the quantity of invariant mass does not change in transformations between "matter" electrons and positrons and energy photons.
Relation to gravity[ edit ] In physics, there are two distinct concepts of mass: The gravitational mass is the quantity that determines the strength of the gravitational field generated by an object, as well as the gravitational force acting on the object when it is immersed in a gravitational field produced by other bodies.
The inertial mass, on the other hand, quantifies how much an object accelerates if a given force is applied to it. The mass—energy equivalence in special relativity refers to the inertial mass. However, already in the context of Newton gravity, the Weak Equivalence Principle is postulated: Thus, the mass—energy equivalence, combined with the Weak Equivalence Principle, results in the prediction that all forms of energy contribute to the gravitational field generated by an object.
This observation is one of the pillars of the general theory of relativity. The above prediction, that all forms of energy interact gravitationally, has been subject to experimental tests.
The first observation testing this prediction was made in The effect is due to the gravitational attraction of light by the Sun. The observation confirmed that the energy carried by light indeed is equivalent to a gravitational mass. Another seminal experiment, the Pound—Rebka experimentwas performed in The frequency of the light detected was higher than the light emitted.
The Law of the Conservation of Mass: The law of the conservation of mass states that mass is always conserved. That is, whatever we do with matter in a closed system we will always have the same amount of substance at the end. For example, if we burn a log, the wood gets lighter as the fuel it contains is used up. However, if we gather together the ashes, all of the tiny smoke particles and the water vapour produced by the burning process and then weigh everything we find that the mass is exactly equal to the mass of the log that was burned.
Mass is just mass, or so it seems, and while it can be chemically altered, such as burned, the total amount in any system remains the same. The Law of the Conservation of Energy: But what about the energy released in burning the log? The energy released in the burning process is "chemical energy", i. Burning the wood released the chemical energy locked up in it. No energy was created in the process and none was destroyed; it was just changed from one sort of energy chemical bonds to other forms of energy heat and light.
In other words the total amount of energy, just like the total amount of mass, remained the same. After many experiments, notably by the scientist for whom the unit of energy is named, James Prescott Joule -it was established that the total amount of energy in a closed system always remains the same.
This is known as the law of the conservation of energy. What Einstein showed via his now famous equation was that mass and energy are in fact the same thing. Each atom of a substance can be thought of as a little ball of tightly packed energy that can be released under certain circumstances. Likewise, we can take energy such as particles of light, called photons and turn it into matter. This was first achieved in the s. That light can be turned into matter is perhaps a rather odd idea, but the picture below shows the first successful experiment in which this was done: Cloud chamber photon decay The picture shows the tracks of two matter particles that have been "created" after a high energy photon decayed, i.
The high energy photon is not in the visible range and has entered the chamber from the bottom of the picture. The Cloud Chamber A cloud chamber is a sealed tank filled with a gas, usually with a magnet to one side of it. When a particle, such as an atom, electron or proton passes through the tank it collides with some of the particles in the gas to produce little clouds that mark its path.
For an electrically neutral particle, such as a neutron, the path will be straight. However, for any particle that is not electrically neutral its path will be bent towards or away from the magnet that forms part of the apparatus.
MP3 file From the soundtrack of the film Atomic Physics. This is a transcript of the recording: