reply fast with explanation
Before the theory of relativity, scientists called the reference point for all motion as,
a. Focal Point
b. The Earth
c. Ether
d. The Sun
fast plz give explanation
Answers
Answer:
Einstein’s theory of relativity has a formidable reputation as
being incredibly complicated and impossible to understand.
It’s not! The principle of relativity itself, the single, simple
idea upon which Einstein’s theory is based, has been around
since the time of Galileo. As we shall see, when it is applied
to objects that are moving extremely fast, the consequences
seem strange to us because they are outside our everyday ex-
perience; but the results make sense and are all self-consistent
when we think about them carefully. We can summarize the
major corrections that we need to make to Newton’s equations
of motion as follows: Firstly, when an object is in motion, its
momentum p is larger than expected, its length l shrinks in
the direction of motion, and time t slows down, in each case
by a factor
γ = 1
1 − v2/c2
, (2.1)
where v is the velocity of the object and c is the speed of light:
c = 299792458m/s(exactly, bydefinition)
= 186, 282miles/second
= 30cm/ns, inunitswecangrasp.This seems confusing at first because we are used to assuming,
for example, that the length l of any object should be constant.
For everyday purposes, the correction is tiny — consider the
International Space Station, moving at 8 km/s in orbit; its
length is about 1 part per billion less than if it were at rest,
and time on board moves more slowly by the same factor. But
for many particles moving near the speed of light, the fact that
time slows down (and hence lifetimes are longer) with velocity
by the factor (2.1) has been well verified. The same applies to
the increasing momentum – which demonstrates immediately
the well-known principle that one can never push an object
hard enough to accelerate it to the speed of light, since, as it
goes faster and faster, you have to push harder and harder to
obtain a given increase in velocity. Loosely speaking, it acts
as though the mass increases with velocity.
Secondly, as we shall discover about halfway through the
course, there emerges naturally what may well be the most
famous equation in the world:
E = mc2
.These formulae were not found experimentally, but theoret-
ically, as we shall see.
Einstein’s 1905 relativity paper, “On the Electrodynamics
of Moving Bodies”, was one of three he published that year,
at age 26, during his spare time; he was at the time working
as a patent clerk in Zurich. Another was a paper explaining
Brownian motion in terms of kinetic theory (at a time when
some people still doubted the existence of atoms), and the
third proposed the existence of photons, thus laying the foundations for quantum theory and earning him the Nobel prize
(relativity being too controversial then).
Einstein wrote two theories of relativity; the 1905 work is
known as “special relativity” because it deals only with the
special case of uniform (i.e. non-accelerating) motion. In
1915 he published his “general theory of relativity”, dealing
with gravity and acceleration. Strange things happen in accel-
erating frames; objects appear to start moving without any-
thing pushing them... During this course we shall only deal
with special relativity.
2.1 The Principle of Relativity
As we use our telescopes to look ever farther out into the
universe, some relevant questions present themselves:
• Is space homogeneous? I.e., is it the same everywhere —
are the laws of physics the same in distant galaxies as they
are here on Earth?
• Is it isotropic — is it the same in all directions, or is there
some defining “axis” or direction that is preferred in some
way? Is, for example, the speed of light the same in all
directions?
• Are the laws of physics constant in time?
• And finally, are the laws of physics independent of uniform
relative motion?
By looking at light from the most distant visible galaxies,
more than 10 billion light years away, we can recognise the
Explanation:
option A
A noun is a word that names something, such as a person, place, thing, or idea. In a sentence, nouns can play the role of subject, direct object, indirect object, subject complement, object complement, appositive, or adjective.A noun is a word that names something, such as a person, place, thing, or idea. In a sentence, nouns can play the role of subject, direct object, indirect object, subject complement, object complement, appositive, or adjective.A noun is a word that names something, such as a person, place, thing, or idea. In a sentence, nouns can play the role of subject, direct object, indirect object, subject complement, object complement, appositive, or adjective.