Could James Webb Prove The Multiverse Theory and Dark Matter?
Launched on Christmas 2021, the James Webb Space Telescope is finally operational and
it has started making new science while orbiting around the Lagrangian point L2, an
imaginary point in space in the Sun-Earth system. James Webb has been defined as the Hubble Space
Telescope successor, even though the two amazing telescopes are quite different from each other.
James Webb will explore the universe as seen in the Infrared Band. It is a spectral range
of wavelengths that we, humans, are not able to see with our own eyes. Studying the universe in
the infrared domain, we are able to see objects that would be otherwise covered by dust clouds.
James Webb's discoveries will revolutionize our world
and our understanding of the universe together.
But what's the real reason for launching this powerful telescope into space?
And could it be helpful to test the multiverse theory and prove the presence of dark matter?
Follow me to get to know the answer to this question and more!
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First of all, James Webb could be really helpful with the determination of the Hubble constant.
From what we know, the universe is expanding: we see distant objects, like galaxies or quasars,
receding away from us, with a velocity that increases the further the object is.
To better understand the concept of the expansion rate of the universe,
think of a muffin batter. You have blueberries on it,
and every blueberry is a galaxy. Somewhere on the muffin, there's your galaxy,
the Milky Way! Now imagine putting the muffin in the oven, and baking it for 15 minutes.
The blueberries (the galaxies) will move apart, the batter expanding everywhere. This is similar
to what happens to the universe. Over time, we get farther away from other galaxies.
It seems all perfect, doesn't it? But, when astronomers try to measure the Hubble constant,
things get harder, because different methods of measurement lead to different expansion rates.
For example, the method based on the study of bright cepheid stars
gives an expansion rate of about 72-73 km/s/Mpc. (km/s per Megaparsec).
However, to make an independent estimate of the Hubble constant, astronomers also make use of
an entirely different kind of star: red giants. Red giants are stars at the end of their lives.
By studying nearby red giant stars at known distances, astronomers can measure the maximum
brightness of these dying stars. Freedman used this maximum red giant brightness to
calculate distances to far galaxies. Using this new red giant method,
Freedman’s new measurement of the Hubble constant was 69.8 km/s/Mpc— between the previously
observed value and the value predicted by mathematical models of the universe’s evolution.
Another independent method to measure the Hubble constant studies is the Cosmic Microwave
Background radiation. But what is it? After the Big Bang, the superheating of
all the matter in the universe released enormous amounts of radiation as photons.
As the universe expanded, this radiation got more and more redshifted. The record
of this radiation and redshifting is in the cosmic microwave background, or CMB.
As of today, we know that the CMB is not uniform, but it's made up of hotter and colder patches
that record the “clumpiness” of matter and energy in the very early phases of the universe.
By combining fundamental physics with estimates of the amount of mass and energy contained
within the universe, cosmologists can model the expansion of the universe from its initial state
to the present day and reproduce the observed clumpiness in the cosmic microwave background.
Cosmologists have repeated this procedure hundreds of thousands
of times to find the combinations of conditions that match observations.
In doing so, they found a value for the Hubble constant of only 67.8 km/s/Mpc.
Could the JWST tell us which one of these measurements is the right one?
Probably yes! The JWST will provide us with the most accurate measurements of
the brightness of stars such as cepheids and red giants, thus drastically decreasing
the uncertainties in the measurements. It will be able to loo through pesky clouds
of space dust that all too often interfere with local astronomers’ measurements.
The Hubble Space Telescope—the previous tool of choice for local astronomers—has far more modest
infrared capabilities; its infrared measurements come at the expense of lower image quality.
As Riess explains, JWST can do both: observe in infrared and maintain high-resolution imaging.
But our powerful telescope could also help us better understand the phenomenon of dark matter.
Astrophysicists don't know if dark matter actually exists.
We only know it is required to explain some observed phenomena, such as the galaxies'
rotation curves of spiral galaxies. When the first astronomers started studying spiral galaxies,
they noticed the behavior of the gas and stars in terms of velocity was different than expected.
They were expecting a rotation curve to be keplerian, which means, they were expecting to see
the velocities of gas and stars in a spiral galaxy decrease a certain radius away from the center.
But this is not what they observed. Instead, they saw that, after a certain radius,
the velocity curve remains constant. This is only possible if some non-luminous matter is present,
that gravitationally interacts with the ordinary matter.
This missing invisible mass is indeed dark matter.
But the dark matter has another interesting effect:
it can deform and stretch the images of faraway galaxies and quasars or objects such as stars. The
phenomenon is known as gravitational lensing, and it is predicted by the General relativity theory.
A gravitational lens can occur when a huge amount of matter, like a cluster of galaxies, creates a
gravitational field that distorts and magnifies the light from distant galaxies that are behind it
but in the same line of sight. The effect is like looking through a giant magnifying glass.
It allows researchers to study the details of early galaxies
too far away to be seen with current technology and telescopes.
Heavy and dense clumps of dark matter would also be able to produce gravitational lensing events.
In this case, JWST will come in handy, because it is very good at spotting them!
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For example, take a look at this image. It is approximately the size of a grain
of sand held at arm’s length, a tiny sliver of the vast universe. The combined mass of
this galaxy cluster acts as a gravitational lens, magnifying more distant galaxies,
including some seen when the universe was less than a billion years old.
This deep field, taken by Webb’s Near-Infrared Camera (NIRCam), is a composite made from images
at different wavelengths, totaling 12.5 hours – achieving depths at infrared wavelengths beyond
the Hubble Space Telescope’s deepest fields, which took weeks. And this is only the beginning.
Researchers will continue to use Webb to take longer exposures,
revealing more of our vast universe. This image shows the galaxy cluster SMACS 0723
as it appeared 4.6 billion years ago, with many more galaxies in front of and behind the cluster.
Much more about this cluster will be revealed as researchers begin digging into Webb’s data.
For what concerns the multiverse theory, modern theories of the big bang predict that our local
universe came into existence with a brief burst of inflation — in other words, a tiny fraction of a
second after the big bang itself, the universe expanded at an exponential rate. It is widely
believed, however, that once inflation starts, there are regions where it never stops. It is
thought that quantum effects can keep inflation going forever in some regions of the universe
so that globally, inflation is eternal. The observable part of our universe would then be just
a hospitable pocket universe, a region in which inflation has ended and stars and galaxies formed.
“The usual theory of eternal inflation predicts that globally our universe
is like an infinite fractal, with a mosaic of different pocket universes,
separated by an inflating ocean,” said Hawking in an interview in 2017.
Astrophysicist Stephen Hawking, however, has never been a fan of the multiverse.
In a paper on the multiverse theory, Hawking and professor Hertog from Luwen University
say this account of eternal inflation as a theory of the big bang is wrong.
Their results, if confirmed by further work, would have far-reaching implications for the
multiverse paradigm. What they believe is that we are not down to a single,
unique universe, but our findings imply a significant reduction of the multiverse,
to a much smaller range of possible universes. To test these results, we need to equip
a spaceship with a special detector capable of studying
the Cosmic Microwave background in detail. But the CMB wavelength is a hundred times longer
than what Webb can detect, so unfortunately our telescope would be helpless here.
What James Webb could find, instead, is some signs of alien life on another exoplanet.
This telescope is really special: it can detect,
for example, water molecules in the atmosphere of such exoplanets.
One method Webb will use for studying exoplanets is the transit method, which means it will look
for the dimming of the light from a star as its planet passes between us and the star.
The image of an exoplanet would just be a spot, not a grand panorama, but by studying that spot,
we can learn a great deal about it. That includes its color, differences between winter and summer,
vegetation, rotation, weather...How is this done? The answer is spectroscopy.
When a planet passes in front of a star, the starlight passes through the planet's atmosphere.
If, for example, the planet has sodium in its atmosphere, the spectrum of the star, added to
that of the planet, will have what we call an "absorption line" in the place in the spectra
where would expect to see sodium. This is because different elements and molecules
absorb light at characteristic energies, and this is how we know where in a spectrum we
might expect to see the signature of sodium (or methane or water) if it is present.
In the infrared wavelengths, molecules in the atmospheres of exoplanets
have the largest number of spectral features. Webb's ultimate goal,
of course, is to find a planet with a similar atmosphere to that of Earth.
Will we ever find one? We just have to wait and see!
What we know for sure is that JWST ones are the
most accurate images and spectra we have ever seen,
and this is only the beginning of the mission. It's easy to imagine how, some months from now,
our understanding of the universe will change. Forever.
Thanks, Webb!
This video ends here! What do you think about JWST?
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