Did you know that our universe is so big that we cannot really approximate its actual size?
Due to the extremely fast rate of the cosmological expansion, scientists came up with a term
called the “observable universe” which is by definition a spherical region containing
all the matter that can be observed from Telescopes on Earth and the space-based probes or even
the exploratory probes such as Voyager I and II whose main objective is to extend the NASA
exploration of the solar system beyond the neighborhood of the outer planets to the outer
limits of the Sun’s sphere of influence, and possibly beyond.
The radius of the observable universe is approximately 46.508 billion years, can you imagine how
big it actually is?
Bearing in mind that it’s not even the actual size of the universe!!
Now that you can imagine how our universe is extremely big, it’s easy to grasp that
it’s filled with wonder-souly massive objects.
Curious to know these objects in order?
Keep watching!
Prior to stating the list of the most massive objects in the universe, it’s crucial to
understand the concept of mass along with the astronomical mass units.
Mass by definition is the measure of the amount of matter in an object usually measured in
grams (g) or kilograms (kg), however due to the difficulties in measuring and expressing
astronomical data in the international system of units (SI units); the Astronomical System
of Units was developed in 1979 in which there was a redefinition of units of mass, time
and length and the astronomical constants as well.
The astronomical unit of mass is the solar mass aka the mass of the sun which is approximately
equal to 1.98892 * 10^(30) kg and it’s the standard unit of describing the mass of stars
and galaxies.
Passage 1 When it comes to cosmology, the term object
is a loose concept because the universe is filled up with so many objects such as planets,
stars, black holes and pulsars.
However, one must ask “is any structure of gravitationally bound matter considered
to be an object?”
If the answer is yes, then we must consider nebulae, galaxies, galaxy clusters and the
clusters of the galaxy clusters as objects as well.
Moreover, we should consider the cosmic web, which is an overarching structure that holds
all the matter in the universe as an object.
Therefore, in this video we are introducing the most massive objects in the universe covering
most of their types in descending order:
10- As you probably know, the most massive object in the universe from the beginning
of time is the universe itself right before the moment of the big bang.
The big bang model states that the universe at the beginning 13.7 billion years ago was
in an extremely hot and dense state, just try to imagine the total mass of the universe
condensed into extremely infinitesimally small point-like singularity.
9- Dark Energy; which constitutes 68% of the universe- you may wonder how on earth would
energy be massive?!
But thanks to Einstein’s energy-mass famous equation E=mc^(2) where c is the speed of
light, transforming energy into mass is trivial.
You may also have heard of the dark energy previously but let me explain its importance
in detail… scientists in the early 1990s were fairly certain about some dynamics of
the universe’s expansion; such that it might have enough energy density to stop its expansion
and recollapse or it might have so little energy that it would never stop expanding,
however, the gravitational forces were certain to slow the expansion as time went on due
to the fact that our universe is full of matter and the attractive force of gravity pulls
all matter together.
However, in 1998, the Hubble Space Telescope (HST) observations of very distant supernovae
showed that a long time ago; the universe was actually expanding more slowly than it
is today.
In other words, the expansion of the universe has not been slowing down due to gravity,
as everyone expected, but it has been accelerating and something was causing this acceleration.
Eventually, theorists still do not know what the correct explanation is but they have given
the solution a name, it’s called the dark energy.
More is unknown than is known about dark energy, the amount of dark energy is known because
we know how it influences the universe’s expansion.
There Are three possible explanations of dark energy, One explanation is that it’s a property
of space -yes space has many amazing properties, many of which are just beginning to be understood-
Einstein was the first to realize that empty space can possess its own energy, furthermore,
it’s possible for more space to come into existence.
And because this energy is a property of space itself, it would not be diluted as the space
expands.
Additionally, as more space comes into existence, more of this space-energy will appear which
will be the reason that the universe will expand faster and faster.
Unfortunately, there are some issues regarding this fancy model and related to the cosmological
constant.
Another explanation of how space acquires energy comes from the quantum theory of matter
which states that empty space is full of temporal particles that are continuously formed and
then disappear via annihilation; yet the total number of these virtual particles is not consistent
with the ratio of the dark energy.
The last explanation for dark energy is that it’s a new kind of dynamical energy fluid
or field which can be considered as something that fills all of space but its effect on
the expansion of the universe is the opposite of that of matter and normal energy.
In conclusion, scientists need more and better data to decide between these models.
8- Dark matter which constitutes 27% of the universe.
Observations made us much more certain about what dark matter is not than what it actually
is; first, it’s called dark because it’s not in the form of stars and planets we observe
everyday.
Observations show that there’s far too little visible matter in the universe to make up
the 27% required by the observations.
Second, dark matter is not in the form of dark clouds of normal matter, matter is made
up of baryons and we are aware of this because we would be able to detect baryonic clouds
by their absorption of the radiation passing through them.
Finally, we are 100% certain that dark matter is not the same as antimatter due to the fact
that we don’t observe the unique gamma rays that are produced when antimatter annihilates
with baryonic matter.
However, there are still a few viable possibilities regarding dark matter.
One of which is that baryonic matter could still make up the dark matter if it all were
concentrated in brown dwarfs or in small dense chunks of heavy elements which are known as
MACHOs the Massive Compact Halo Objects.
On the other hand, there’s a most common view which states that dark matter is not
baryonic at all but it’s made up of more exotic particles like Axions or WIMPs the
Weakly Interacting Massive Objects.
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Passage 2
7- According to a study published by the Los Alamos national laboratory, the most massive
object in the universe is calculated to be a cluster of galaxies with total mass equal
to 3.8*10^(15) solar masses.
The study also states that the Abell 2163 and Abell 370 clusters are viable candidates
for the most massive clusters in the universe; these findings motivate further observations
and further surveys will explore larger volumes, therefore it’s highly possible that the
most massive object in the universe may be identified within the next decade.
6- As far as the astronomers know, the most massive galaxies in the universe contain approximately
5*10^(11) solar masses of material; our galaxy the Milky Way, for comparison, has a total
mass of roughly about 10^(11) solar masses.
Typically about 80% of the mass in the galaxy is in the form of stars and most of the rest
is gas.
Not to mention that astronomers are really trying to understand how galaxies of all types
form, in particular, they are interested in the giants because they appear to exist in
the early universe.
Our universe is about 13.7 billion years old, and the Milky Way along with other galaxies
in our neighborhood benefited from having all that time to grow larger.
However, some of the most massive galaxies have been found back when the universe was
only a few billion years old; the question is how did they get to be so big so fast?
A partial answer to this question can be found by looking at the production of new stars
in a galaxy, as well as the growth of its central massive black hole.
Luckily, both of these processes can be studied in distant objects since they produce bright
radiation in the infrared, with the latter process also producing strong radio and X-ray
emission.
5- When it comes to single objects, the most massive single object in the universe is the
S50014+81 supermassive black hole which was discovered in 1981.
It’s about 12.07 billion light years from the Earth, located precisely near the high
declination region of the constellation Cephus.
The mass of this supermassive black hole is approximately 40 billion solar masses!
You may ask yourself how big of a star would S50014+81 have been before it turned into
a black hole?
However, it’s a question based on the wrong premise that supermassive black holes originate
from stars that turned into a black holes.
And they actually don’t!!
In fact, there’s a limit to the mass of any star, which is approximately 200 solar
masses.
Above that certain limit, a star would not be stable and lose any additional mass to
the surrounding space.
Therefore, black holes like S50014+81 probably form from a cluster of several hundred stellar
black holes - each of which is no larger than 50 solar masses- that collide and form a single
medium sized black hole with a mass of a few thousand solar masses.
On reaching that stage, they start to grow by accreting nearby materials such as dust,
gas and dark matter to grow very quickly into supermassive black holes.
4- The most massive black hole in our galaxy is known as Sagittarius A-star (A*), its mass
is estimated as 4.1*10^(6) solar masses.
It’s located in the center of the Milky Way which makes it almost a quasar.
Findings show that it’s 26,000 light years away from us; and it’s 44 million km in
diameter which is approximately the same distance between the Sun and Mercury.
These numbers are very large for a black hole since they are extremely dense and occupy
less volume.
When it comes to observations, it’s not visible to the naked eye, which is a trivial
fact, since black holes don’t let light escape.
Additionally, it was very hard for scientists to discover it and gather data due to the
huge dust between Earth and the center of our galaxy where it’s located.
3- The most massive star known to exist in the universe is the star R136a1 which is more
than 265 solar masses.
Astronomers are still trying to understand how this star can even exist; due to the mass
limit of stars.
In addition to being the most massive, it’s also the most luminous at nearly 9 millions
times the luminosity of our sun.
It’s a part of a supercluster in the Tarantula Nebula of the large Magellanic cloud, which
happens to be the location of some other massive stars in the universe!
2- UY Scuti is the most massive star in the Milky Way with mass approximately equal to
30 solar masses.
However, it’s not distinct because of its mass only but also because of its large radius
which is estimated to be 1700 times the radius of the sun.
Therefore, this single star is so large that its outer surface will extend far beyond the
orbit of the planet Jupiter that lies about five times further from the sun than the Earth.
1- On narrowing our scope to be the solar system instead of the whole universe, we will
find that Jupiter is the most massive planet in the solar system with mass equals to 0.001
solar masses that is 317.8 times the mass of Earth, its mass is so big that it actually
equals 2.5 the mass of all the other planets of the solar system combined!
Jupiter is also called a “Failed Star” due to the fact that it’s made of the same
elements as stars which are hydrogen and helium, however it’s not massive enough to have
the internal pressure and temperature necessary to cause the hydrogen to fuse to helium in
a process called Hydrogen Fusion which is the energy source that powers the sun and
the other stars during the main sequence of their lifetime.
Thanks For Watching Everyone!!
Do you know other comparable massive objects in the universe?
Can you guess what other processes that support the star at the end of its main sequence?
Did you learn anything new in this video?
Let me know in the comments below, be sure to subscribe, and I’ll see you next time
on the channel!