In the beginning, there was nothing. Then bang. Our Universe emerged in an explosion of light and energy. Current theories say that it all began 13.7 billion years ago. Or did it? Let’s shed some light on this. So, how fast is the Universe expanding? Will the Universe and everything in it ever die? And why could our Universe have existed before the Big Bang? What’s a singularity?
Transcript and sources:
Get our 100 best episodes in one mind-blowing book:
Join this channel to get access to perks:
Watch more what-if scenarios:
T-shirts and merch:
Suggest an episode:
Feedback and inquiries:
What If elsewhere:
What If in Spanish:
What If in Mandarin:
What If is a mini-documentary web series that takes you on an epic journey through hypothetical worlds and possibilities. Join us on an imaginary adventure through time, space and chance while we (hopefully) boil down complex subjects in a fun and entertaining way.
Did you know that our universe is so big that we cannot really approximate its actual size?
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!
The Most Massive Objects in the Universe.
Subscribe for more videos:
Business Enquiries: email@example.com
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.
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.
8- Dark matter which constitutes 27% of the universe.
We know how terrifying and powerful black holes can be, but what comes second place in terms to it in terms of overall awesomeness? Join us today as we learn about neutron stars!
Subscribe for more videos:
One of the most popular outer space entities that pop culture love to revolve about is the black hole. We’ve seen various movies, TV programs, even some songs talk about how magnificent and mysterious they are. But what if black holes aren’t the only objects that we should be amazed with?
Of course we have a lot of picks for that matter, but the particular thing we would talk about today is the star that ranks number 1 in the universe in terms of density: the neutron stars.
Okay, astro fans, I can hear you argue and say “No, black holes are the densest objects in the universe!” But let me tell you this: remember how black holes work? They are effectively stars that collapsed to an almost zero volume, which results in their enormous gravitational force. If they effectively are dimensionless, can we really say that they are “objects”?
We can’t be really sure, and that’s something that only philosophy can answer, but while we’re here at the subject of definitions and what we actually know for certain, let’s just say the one we can categorize as the densest object, quote-unquote, is the neutron star.
And no, a neutron star is not a subatomic particle which grew to the size of the star. It isn’t also a bunch of neutrons agreeing to somehow collectively come together to form a humongous star. Although we can effectively say that a neutron star is like a giant atom, we’ll get to that later.
For now, I want to discuss how neutron stars are born and why they are like Phoenixes: how from the ashes of their old corpses, they rise up and fly with their new, replenished lives!
I know you already know this if you’re an astro buff, but to some of our viewers out there who are new, first of all, welcome! We hope we spark your curiosity more through our videos!
Anyway, stars were discovered to follow some kind of lifecycle, just like us living beings on Earth. They too, get born, have a childhood phase, then grow to adulthood, then also die, after certain circumstances.
A star’s usual routine involves fusing hydrogen into helium. Quite honestly, in its lifetime, that’s all it ever does. Now, as we know from basic nuclear physics, when we fuse atoms together, it creates energy. The energy that the fusion in the star creates is countered by the gravitational force towards its center, effectively keeping the balance and preventing it from collapsing towards its center. As long as this goes on, everything is good and well at a star’s life.
But of course, like all lives, stars experience a tipping point in theirs.
Remember how stars burn hydrogen to fuse to helium? Well, eventually, stars run out of hydrogen to fuse, so they fuse helium instead, forming elements such as carbon and oxygen. The energy pushes out the borders of the star causing it to move to its giant phase, until the pressure from electron degeneracy collapses the core of the star, and expelling its outer layer leaving a white dwarf.
For heavy mass stars, a number of times larger than the mass of our own Sun, the story is different.
The same as earlier, when the star runs out of hydrogen to fuse, it begins to fuse heavier elements. The difference this time is that the collapse caused by gravity is so extremely strong, way stronger than what we described earlier, that the fusion goes to Neon, to Oxygen, to Silicon, then finally to Iron.
As this happens, the outer layer of the star begins to fatten up faster as time goes by.
When the core of the star is finally iron, fusion can no longer take place, as iron is stubborn this way. We can imagine at this point, there is no more energy resulting from fusion. So what if that happens? The own weight of the star collapses in itself, effectively crushing it to the size of up to around a 10 kilometer radius. It’s like compressing the star to about the size of Malta!
Now, we know how subatomic particles don’t want to get near each other, right? We can practically say that an atom is made of empty space. However, the strength of the gravitational force that occurs when a heavy mass star collapses crushes this space in between, merging the protons and electrons together to form neutrons, with some neutrinos in excess.
But the extravaganza of energy doesn’t end there! See, neutrons hate being compressed towards one another, too. Just like protons and electrons. The collapse can only occur up to a certain moment where the neutrons form a lattice-like structure, the crushing in stops. By the way, this sudden halt is what we call neutron degeneracy pressure.
From the kind of star it is, to its impact on our world, and more! Join me as we explore the Sun: Facts and History.
Subscribe for more videos:
Business Enquiries: firstname.lastname@example.org
8. Our Star
Without a doubt, if you were to list the “most important things in the solar system we live in”, the Earth may be No.1, but the sun is No.2. And for all the reasons that you might expect and know.
Its gravity holds the solar system together, keeping everything from the biggest planets to the smallest particles of debris in its orbit. Electric currents in the Sun generate a magnetic field that is carried out through the solar system by the solar wind—a stream of electrically charged gas blowing outward from the Sun in all directions.
The connection and interactions between the Sun and Earth drive the seasons, ocean currents, weather, climate, radiation belts and aurora.
In short, and in long, the sun is vital to just about everything we do on this planet, and we rely on the sun to do MANY things, even though we’re honestly not controlling anything that it does. Which is a bit of an odd thing for humanity as humans like to control EVERYTHING that has to do with us.
The sun is something we see almost every day (obviously unless cloud cover is blocking it or an eclipse is happening) and even when we don’t see it, we feel its presence. It’s more than just a ball of light in the sky, it’s an energy source, a lifeline in many respects, and as noted above, it helps shape our planet in various ways that would detrimental if it WASN’T doing it.
So if someone was to honestly ask you just how important the sun is, you should tell them all the ways we need the sun, our star, to shine on.
7. Distance From Earth and Its Size
With a radius of 432,168.6 miles (695,508 kilometers), our Sun is not an especially large star—many are several times bigger—but it is still far more massive than our home planet: 332,946 Earths match the mass of the Sun. The Sun’s volume would need 1.3 million Earths to fill it.
Which at first might seem like a bad thing. After all, would we WANT to have a giant ball of fire and radiation just lurking out there that can swallow us whole if it felt like it? Honestly, yes, yes we would, and for a very simple reason, its distance from the Earth.
The Sun is 93 million miles (150 million kilometers) from Earth. Which is a very LONG ways away, and in fact it’s such a distance that they came up with a term for it via “Astronomical Unit”. So when you hear that a planet or star is say 103 AUs away, that means it’s 103 times the distance between the Earth and the sun.
Going back to the distance itself, you might think that this is a “very long way away” from the entity that gives us light and essentially, life. But actually, it’s better that we’re NOT closer to the sun for a whole host of reasons.
Sunlight and its energy dissipates the farther you get away from it. Which is why there is such thing as a “Habitable Zone” in regards to stars where life can exist as well as water and other key things needed for life.
The closer you are to a star, the more impact you’re going to get from its heat and light. The farther you are from a star, the less likely you’re going to get heat and light in the amounts you need. Lest you think we’re exaggerating this, we have the perfect examples for this. It’s called Mercury, Venus and Mars.
Mercury is the closest planet to the sun, and it’s scorching hot as a result. It’s average temperature is 800 degrees Fahrenheit. Plus, because it’s so close to the sun it’s tidally locked, meaning that it has one “side” always facing the sun, and the other side is always away from it.
In regards to Venus, it’s our “twin” but also a case of the suns energy turning it into something else entirely. A buildup of heat and excess carbon dioxide turned it into a “Runaway Greenhouse Planet” which makes it so hot that it can melt lead. And it’s also the hottest planet in the solar system because of the greenhouse effect which was caused by the suns’ radiation.
Heading to Mars, it’s so far away from the Sun that it can’t absorb the sunlight and energy like we do on Earth, so its average temperature is -81 degrees Fahrenheit. Not to mention it doesn’t have a typical atmosphere in any sense so various solar and cosmic rays bombard the planet. And it’s so far away from the sun that even if Earth settled on the planet, using solar panels to get energy for colonies wouldn’t be as viable as you think because the distance is so great.
So as you can see, it’s GOOD that we are 93 million miles away from the sun, it’s the literal perfect spot to be in to get the positive effects of the sun without many of the negatives.