Hot answers tagged mass
7
The idea at the most simplest level comes from the relation $E^2-p^2c^2=m^2c^4$. This is the Einstein relation $E=mc^2$ for a particle of mass $m$ traveling with relativistic momentum $p$. The idea is that if $m^2<0$, and therefore $m$ is imaginary, that $E^2-p^2c^2 < 0$ or $E^2<p^2c^2$. With real mass this relation is the other way around and ...
7
Energy and matter are not the same. Matter is a type of thing, whereas energy is a property of a thing, like velocity or volume. So your premise is flawed. In particular:
there's no such thing as "a solid state of energy" - hopefully it makes sense that a property of something does not have states
energy is not represented by waves, though it is a property ...
3
The thing about energy becoming particles is not entirely true. Quantum mechanics explains that particles themselves are waves. The energy that forms mass, however, is not a part of the particles themselves. For subatomic particles such as electrons and quarks, their mass is caused by their interaction with the Higgs field. The energy itself is stored in ...
3
You take any mathematical model that includes mass as a parameter, e.g. Newton's Laws, Special Relativity, General Relativity, etc, and put in the mass as a negative number. The model will then make predictions about what will happen, but because you have chosen physically unrealistic starting conditions the predictions of the model will be physically ...
2
I disagree with Will. In all cases I could conceive, the scale directly measures the Normal force acting on you. For example, if you are in an accelerating elevator, the scale would read whatever your calculated normal force is.
Since I'm currently studying Chemistry, I would like to add that chemists make no distinction between mass and weight. In fact, ...
2
It measures the force your body exerts on the scale due to gravity. That is, it measures your weight force $F_w = mg$. A low-tech example of this is a spring scale which uses the scale displacement, $x$, due to your weight force and the known spring constant, $k$, to determine your mass via
$kx = mg \implies m = \frac{k}{g} x$
The scale then reads out this ...
1
What is conserved is energy and momentum, not mass.
For a massive particle, mass is the energy at rest (when the particle is not moving)
For instance in a 2 particles => 2 particles reaction, you will have:
$E_1 + E_2 = E_3 + E_4$
$\vec p_1 + \vec p_2 = \vec p_3 + \vec p_4$
In the case of massive particles collisions at high energies, you have to use, ...
1
All depend on the context. If Dirac's theory of antiparticles one has get a negative energy, so why one should not use a negative mass if it is convenient for the formalism. For example, in semiconductor physics, the negative effective mass is related to the curvature of the dispersion law describing dependence of the quasiparticle's energy on its momentum. ...
1
Majorana and Dirac equations are usually considered as two different and mutually exclusive equations. However, both of them can be considered as a special cases of the more general equation.
Let's start with Dirac equation written in terms of the "left" ($\xi$) and "right" ($\dot\eta$) spinor components:
\begin{equation}
\begin{array}{c}
...
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