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3827 - EINSTEIN
- How he changed the world? Albert Einstein (1879-1955) is one of the
most famous scientists of all time, and his name has become almost synonymous
with the word "genius." There are many ways Einstein changed the
world.
--------- 3827 - EINSTEIN - How he changed the world?
- There are many ways Einstein changed the
world:
1. Space-time
2. Einstein's
equation: E = mc^2
3. Lasers
4. Black holes
and wormholes
5. The expanding
universe
6. The atomic
bomb
7. Gravitational
waves
-
- While Einstein's reputation owes something
to his eccentric appearance and occasional pronouncements on philosophy, world
politics and other non-scientific topics, his real claim to fame comes from his
contributions to modern physics, which have changed our entire perception of
the universe and helped shape the world we live in today.
-
- 1. SPACE-TIME. Einstein's theory of special relativity
changed the way we think about space and time and established a universal speed
limit of the speed of light.
-
- One of Einstein's earliest achievements, at
the age of 26, was his theory of special relativity. It deals with relative motion in the special
case where gravitational forces are neglected.
-
- This completely changed the way physicists
think about space and time. In effect, Einstein merged these into a single
space-time continuum. One reason we think of space and time as being completely
separate is because we measure them in different units, such as miles and
seconds, respectively. But Einstein showed how they are actually
interchangeable, linked to each other through the speed of light, approximately
186,000 miles per second.
-
- Perhaps the most famous consequence of
special relativity is that nothing can travel faster than light. But it also
means that things start to behave very oddly as the speed of light is
approached.
-
- If you could see a spaceship that was
traveling at 80% the speed of light, it would look 40% shorter than when it
appeared at rest. And if you could see inside, everything would appear to move
in slow motion, with a clock taking 100 seconds to tick through a minute. This
means the spaceship's crew would actually age more slowly the faster they are
traveling.
-
- 2. EINSTEIN'S EQUATION: E = MC^2. An unexpected offshoot of special relativity
was Einstein's celebrated equation E = mc^2, which is likely the only
mathematical formula to have reached the status of a cultural icon. The
equation expresses the equivalence of mass (m) and energy (E), two physical
parameters previously believed to be completely separate.
-
- In traditional physics, mass measures the
amount of matter contained in an object, whereas energy is a property the
object has by virtue of its motion and the forces acting on it. Energy can
exist in the complete absence of matter, for example in light or radio waves.
-
- However, Einstein's equation says that
mass and energy are essentially the same thing, as long as you multiply the
mass by c^2, the square of the speed of light, to ensure it ends up in the same
units as energy.
-
- This means that an object gains mass as it
moves faster, simply because it's gaining energy. It also means that even an
inert, stationary object has a huge amount of energy locked up inside it.
Besides being a mind-blowing idea, the concept has practical applications in
the world of high-energy particle physics.
If sufficiently energetic particles are smashed together, the energy of
the collision can create new matter in the form of additional particles.
-
- 3. LASERS are an essential component of
modern technology and are used in everything from barcode readers and laser
pointers to holograms and fiber-optic communication. Although lasers are not
commonly associated with Einstein, it was ultimately his work that made them
possible.
-
- The word laser, coined in 1959, stands for
"light amplification by stimulated emission of radiation" and
stimulated emission is a concept Einstein developed more than 40 years earlier.
-
- In 1917, Einstein wrote a paper on the
quantum theory of radiation that described, among other things, how a photon of
light passing through a substance could stimulate the emission of further
photons.
-
- Einstein realized that the new photons
travel in the same direction, and with the same frequency and phase, as the
original photon. This results in a cascade effect as more and more virtually
identical photons are produced.
-
- As a theoretician, Einstein didn't take the
idea any further, while other scientists were slow to recognize the enormous
practical potential of stimulated emission. But the world got there in the end,
and people are still finding new applications for lasers today, from anti-drone
weapons to super-fast computers.
-
- 4. BLACK HOLES AND WORMHOLES. Einstein's theory of special relativity
showed that space-time can do some pretty weird things even in the absence of
gravitational fields. But that's only the tip of the iceberg, as Einstein
discovered when he finally succeeded in adding gravity into the mix, in his
theory of general relativity.
-
- He found that massive objects like planets
and stars actually distort the fabric of space-time, and it's this distortion
that produces the effects we perceive as gravity.
-
- Einstein explained general relativity
through a complex set of equations, which have an enormous range of
applications. Perhaps the most famous solution to Einstein's equations came
from Karl Schwarzschild's solution in 1916, a black hole.
-
- Even weirder is a solution that Einstein
himself developed in 1935 in collaboration with Nathan Rosen, describing the
possibility of shortcuts from one point in space-time to another. Originally
dubbed Einstein-Rosen bridges, these are now known to all fans of science
fiction by the more familiar name of “wormholes”.
-
- 5. THE EXPANDING UNIVERSE. One of the first things Einstein did with
his equations of general relativity, back in 1915, was to apply them to the
universe as a whole. But the answer that came out looked wrong to him. It
implied that the fabric of space itself was in a state of continuous expansion,
pulling galaxies along with it so the distances between them were constantly
growing. Common sense told Einstein that this couldn't be true, so he added
something called the “cosmological constant” to his equations to produce a
well-behaved, static universe.
-
- But in 1929, Edwin Hubble's observations of
other galaxies showed that the universe really is expanding, apparently in just
the way that Einstein's original equations predicted. It looked like the end of
the line for the cosmological constant, which Einstein later described as his
biggest blunder.
-
- Based on more refined measurements of the
expansion of the universe, we now know that it's speeding up, rather than
slowing down as it ought to in the absence of a cosmological constant. So it
looks as though Einstein's "blunder" wasn't such an error after all.
-
- 6. THE ATOMIC BOMB. First test explosion of atomic bomb,
Alamogordo, New Mexico, USA, 1945.
Einstein is occasionally credited with the "invention" of
nuclear weapons through his equation E = mc^2, but the link between the two is
tenuous at best. The key ingredient is the physics of nuclear fission, which
Einstein had no direct involvement with.
-
- Even so, he played a crucial role in the
practical development of the first atomic bombs. In 1939, a number of
colleagues alerted him to the possibilities of nuclear fission and the horrors
that would ensue if Nazi Germany acquired such weapons.
-
- Eventually, he was persuaded to pass on
these concerns in a letter to the president of the United States, Franklin D.
Roosevelt. The ultimate outcome of Einstein's letter was the establishment of
the Manhattan Project, which created the atomic bombs used against Japan at the
end of World War II.
-
- Einstein died in 1955, but his huge
scientific legacy continues to make headlines even in the 21st century. This
happened in a spectacular way in February 2016, with the announcement of the
discovery of gravitational waves — yet another consequence of general
relativity. Gravitational waves are tiny
ripples that propagate through the fabric of space-time.
-
- Einstein never quite made up his mind whether
gravitational waves were predicted or ruled out by his theory. And it took
astronomers decades of searching to decide the matter one way or the other.
-
- The discovery of gravitational waves has
given astronomers a new tool for observing the universe, including rare events
like merging black holes.
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January 13, 2022 EINSTEIN
- How he changed the world? 3827
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