- 3907 - Einstein Ionized the Universe? The James Webb Space Telescope can’t study the radiation coming out of the galaxies directly, because that radiation gets absorbed by the billions of light-years worth of matter between us and those galaxies. So instead they had to look for other clues.
------------ 3907 - Einstein Ionized the Universe?
- Billions of years ago our universe was a lot smaller and a lot hotter than it is today. At very early times it was so small and hot that it was in the state of a “plasma”, where electrons were separated from atomic nuclei.
-
- But when
the universe was roughly 380,000 years old, it cooled to the point that
electrons could recombine onto their nuclei, forming a soup of neutral atoms.
-
- Observations
of the present-day universe reveal that almost all the matter in the universe
is not neutral at all. Instead it’s “ionized”, once again in the state of a
plasma. Something had to happen in the intervening billions of years to transform
the neutral gas of the cosmos into an ionized plasma.
-
- Astronomers
call this event the “Epoch of Reionization” and suspect that it happened within
the first few hundred million years after the Big Bang. But they are not sure
how this transformational event proceeded.
-
- One of the
great debates in modern cosmology is the source of this “reionization”. One
hypothesis is that quasars are responsible. Quasars are the ultra bright cores
surrounding supermassive black holes which pump out enormous amounts of high
energy radiation.
-
- This
radiation could easily flood the universe and transform it from neutral to
ionized. But the problem with this hypothesis is that quasars are relatively
rare, and so they have difficulty covering the volume of the universe.
-
- Another
hypothesis is that young galaxies rich with star formation are responsible. In
this scenario the process of ionizing the neutral gas is more spread out
throughout the universe.
-
- Each
individual galaxy is only capable of ionizing the gas in its nearby vicinity,
but since there are so many galaxies it’s possible to reionization the entire
universe. But the only way to do this
is if enough high energy radiation leaks out of galaxies and into the
surrounding medium.
-
- Using the
James Webb’s ability to study distant galaxies, they were able to measure how
compact the galaxies were, and how rich in star formation they were. They were
then able to compare these galaxies to similar galaxies found in the present
day universe to create an estimate of the amount of radiation leaking from
them.
-
- They
estimate that on average the galaxies in the early universe leaked roughly 12%
of their available high energy photons. This is just enough to potentially
reionization the entire cosmos in a relatively short amount of 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”, so-called because it deals with relative motion in the special
case where gravitational forces are neglected.
-
- It was one
of the greatest scientific revolutions in history, completely changing 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. But Einstein showed how they are
actually interchangeable, linked to each other through the speed of light,
186,000 miles per second. E-mc^2
-
- 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.
-
- An
unexpected offshoot of special relativity was Einstein's celebrated equation E
= mc^2. 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. Additionally, 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,
which is a very big number to, (670,633,500 mile per hour squared), 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. If
sufficiently energetic particles are smashed together, the energy of the
collision can create new matter in the form of additional particles.
-
- 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.
-
- In 1935
Einstein and Nathan Rosen described the possibility of shortcuts from one point
in space-time to another, known as Einstein-Rosen bridges. Einstein's theory of
special relativity showed that space-time can do some pretty weird things even
in the absence of gravitational fields.
-
- 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”.
-
- 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.
-
- That wasn't
the end of the story, however. 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.
-
- In February
2016, with the announcement of the discovery of gravitational waves was yet
another consequence of general relativity. Gravitational waves are tiny ripples
that propagate through the fabric of space-time, and it's often bluntly stated
that Einstein "predicted" their existence.
-
- The Laser
Interferometer Gravitational-Wave Observatories (LIGO) in Hanford, Washington,
and Livingston, Louisiana. As well as being another triumph for Einstein's
theory of general relativity, the discovery of gravitational waves has given
astronomers a new tool for observing the universe, including rare events like
merging black holes.
- The more we
learn the more we find there is still more that is unknown.
-
March 8, 2023 3907 -
Einstein Ionized the Universe?
3907
----------------------------------------------------------------------------------------
----- Comments appreciated and Pass it on to
whomever is interested. ---
--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email feedback, corrections, request for
copies or Index of all reviews
--- to:
------ jamesdetrick@comcast.net ------
“Jim Detrick” -----------
---------------------
--- Wednesday, March 8, 2023 ---------------------------
-
No comments:
Post a Comment