Name: The Scariest Place in the Universe? - Nuclear Engineer Reacts to Kurzgesagt
Uploaded: 2026-03-13T21:49:36.000Z
Duration: 18 min 46 s
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Or zooming away from Earth at thousands of times the speed of light.

Alright, it's time for some more kurzgesag.

For those of you who don't know me, I'm Tyler Fulst.

I'm a nuclear engineer with a little over 10 years of experience in the commercial nuclear power industry.

From engineering operations to emergency response.

I don't claim to know everything there is nuclear, but I can certainly share some knowledge.

The vast majority of the cosmos is voids.

Gigantic unfathomably large spaces of empty nothingness.

Yeah, density figures out to about a hydrogen atom every few cubic meters compared to a densely packed nuclear reactor at thousands of kilograms per cubic meter, or at about 1 kg per cubic meter.

So the universe in general is pretty empty.

But the voids are that extreme end of emptiness.

Though it isn't exactly nothing, it's still something.

You still have dark matter, trace gas, radiation and quantum fields.

After all, even the best vacuum chambers that you design on Earth still have millions of particles per cubic centimeter.

But these voids are going to be the largest low density regions that have been observed.

Bubbles of eternal light stretching hundreds of millions of light years.

Almost entirely devoid of galaxies, stars or light.

The Milky Way galaxy is only about 100,000 light years across, so this super void is thousands of times larger than that.

And galaxies itself are already fairly sparsely populated.

You could think theoretically fly through the entire galaxy without hitting anything, but

you still have some dark matter kind of acting as the scaffolding of the fabric of the universe.

And galaxies form where that structure becomes dense.

There's a whole lot about this sort of stuff that we just don't know.

These voids are where the structure never accumulated enough mass to collapse into galaxies.

Voids are not just the absence of stuff, but weird worlds of darkness that are growing.

Similar to plasma physics or fluid instability, when density variations exist, they have a tendency to grow over time.

So you end up with something that looks kind of foamy or bubbly, or this cosmic sponge, dark sponge here that you see right here in their illustration.

Drifting, colliding and merging with each other.

Inside them, space itself is stretched violently and it's almost impossible to enter.

So it's about matter flowing outward to denser regions and cosmic Expansion is gonna be a little faster in low density regions.

Kind of like air bubbles rising in water.

The density gradient is driving motion now.

There's nothing really stopping you from any them over time.

Point a spacecraft at them, you'll get there eventually.

But there's nothing really remarkable worth visiting there.

But provided you could leave your galaxy and expend that much energy to do so, that energy cost is larger than anything that the void would do to stop you from going there.

Voids are weird and scary, but they sculpt the entire universe and may ultimately decide its fate.

Kind of like astrophysicists referring to it as the cosmic web, where you got filaments, sheets, clusters, bubbles.

Those voids take up a lot of that volume and push it into clusters.

Today we know of over 8,000 voids and supervoids, and we keep discovering more.

No matter how large a cluster or supercluster of galaxies gets, there always seems to be an even larger void nearby.

Kind of like a fractal system where patterns repeat at multiple scales.

I mean, no, this isn't going to be a perfect fractal, but certainly a resemblance.

Jump off the cosmic cliff and drop into the heart of cosmic nothingness, the loneliest place in the universe.

You're zooming away from Earth at thousands of times the speed of light, leaving our.

Okay, so assuming faster than light tech.

Otherwise it would take too long to explain there.

But yeah, unfortunately, we haven't found out a way to go faster than the speed of light.

Special relativity gets you every time, doesn't our solar system and our solar neighborhood behind now we see the entire Milky way with its 200 billion stars and dozens of dwarf galaxies zipping around it.

And each star is a massive nuclear fusion reactor with enormous energy output, planetary systems, raw materials, which just shows you the sheer resource potential of galaxies.

Of course, in this video, if we have technology capable of going faster than light this quickly, going, leaving our galaxy behind, going that much faster than the speed of light.

Yeah, we're probably beyond these material resources at this point.

Probably a Kardashev Type 3 civilization is the assumption in this video.

Two and a half million light years away on a collision course is giant Andromeda and its own swarm of satellite galaxies.

We're now moving a million times faster than the Speed of light, seeing the Local group of over 50, if we went that fast, in a matter of seconds, we're going way over a million times faster than light.

A million times faster than light would still take you over a month to go from one side of the Milky Way to the other, because the Milky Way is 100,000 light years across, is woven together by gravity, rivers of gas and invisible scaffolds of dark matter.

What's interesting is this one is bound, this Local Group, meaning that cosmic expansion will not tear it apart.

I guess we can think of it as being on the same scaffolding, the same universal structure that isn't going to expand away from each other.

Okay, so they're getting at the accelerating expansion rate of the universe that distant galaxies will eventually become unreachable, even if you travel near light speed forever.

But if you're traveling, traveling faster than light, this much faster than light, then yeah, sure, you can absolutely reach it.

But again, we're talking hyper advanced type 3 civilization technology here, which is far beyond our horizon.

So, yes, it would be as impossible as traveling faster than light for you, apparently, as we zoom away even faster.

A colossal wall of more than 2,000 galaxies spread over roughly 100 million light years.

You're right on the edge of the cosmic cliff where the true deep darkness begins.

A gigantic empty bubble 200 million light years across.

So that's the adjacent structure to our galaxy group.

It's one reason why our galaxy is apparently moving away from that section of the universe.

That is to say, we're being gravitationally pulled to denser structures and away from emptier ones.

If it was a bright thing and not absolute darkness, it would fill 40% of the night sky we see from Earth.

All around us are dozens of such superclusters and gigantic voids filled with suffocating emptiness.

I appreciate the delivery, but no more suffocating than space.

And space General traveling towards the greatest and emptiest nothing in existence.

Right into the center of the boot is supervoid, A cosmic desert around 300 million light years wide.

So gigantic it should contain thousands of galaxies.