| The laws list: N |
The laws list N
NA to null experiment.
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N.
- negative feedback
principle
-
- The idea that in a system where
there are self-propagating circumstances, those new circumstances tend to
act against previously existing circumstances. Such a principle is really a
restatement of a
conservation law.
Example Lenz's law.
-
- newton; N (after Sir I. Newton,
1642-1727)
-
- The derived
SI unit of
force, defined as the force required to give a mass of 1
kg an
acceleration of 1
m/s2;
it thus has units of
kg
m/s2.
-
- Newton's law of
universal gravitation (Sir I. Newton)
-
- Two bodies attract each
other with equal and opposite forces; the magnitude of this force is
proportional to the product of the two masses and is also proportional to
the inverse square of the distance between the centers of mass of the two
bodies; mathematically,
F = (G
m M/r2) e,
where m and M are the masses of the two bodies, r is
the distance between. the two, and e is a unit vector directed from
the test mass to the second.
-
- Newton's laws of motion (Sir
I. Newton)
-
-
- Newton's
first law of motion
-
- A body continues in its state of constant velocity (which may be
zero) unless it is acted upon by an external force.
-
- Newton's second
law of motion
-
- For an unbalanced force acting on a body, the acceleration produced
is proportional to the force impressed; the constant of proportionality
is the inertial mass of the body.
-
- Newton's third
law of motion
-
- In a system where no external forces are present, every action force
is always opposed by an equal and opposite reaction force.
-
- Noether theorem (Noether)
-
- A theorem which demonstrates that symmetries
are what gives rise to conserved quantities. For instance, translational
symmetry (the fact that the laws of physics work the same in all places)
gives rise to conservation of momentum, since position and momentum are
complementary. Additionally, conservation of energy is indicated by time
symmetry, and conservation of angular momentum is indicated by isotropy.
-
- no-hair conjecture (1960s)
-
- The conjecture (proved in the 1970s and
1980s) within general relativity that a black hole has only three salient
external characteristics: mass, angular momentum, and electric charge. All
other properties (including baryon number, lepton number, strangeness, etc.)
are destroyed as matter falls into the horizon.
Note that there is some indication that
quantum mechanical considerations in quantum gravity will result in a
"quantum hair" coming into play. However, that 1. would constitute
a prediction of a theory which does not yet formally exist, and 2.
is utterly insignificant for solar-massed black holes, the only types that
can be formed today.
-
- null experiment
-
- An experiment which, after being executed,
yields no result. Null experiments are just as meaningful as non-null
experiments; if current theory predicts an observable effect (or predicts
there should be no observable effect), and experimentation (within the
required accuracy) does not yield said effect, then the null experiment has
told us something about our theory.
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