How the universe is way bigger than you think | (African Guy Reacts)

Hey Guys, Today I'll be reacting to how the universe is way bigger than you think. This was mindblowing...

MUSIC: Track: Millbrook - Lost Without You (ft. Felix Samuel) [NCS Release]
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[seancurtis]

I can always respect a person expanding their knowledge and being willing to ask questions.

[garyhaines]

They discovered all this due to light. They can ascertain how far or big something is because we have instruments that can tell us how far it has traveled.

[dmwalker]

Carl Sagan once said, 'The universe is a pretty big place. If it's just us, seems like an awful waste of space.' We'll never visit all of it, so in that sense, it literally can't all be for us. I personally don't think it's 'for' anything in particular, but just the sheer size and number of planets would make it almost unbelievable that life only ever emerged on one of them, and it just happens to be this one.

[Yawnzee_]

I try to watch this video atleast once a week, it really helps put my problems into perspective. I believe there is life out there, it would be ignorant of us to think we are the only lifeforms in this entire universe.

[megatwingo]

How the scientists know, that all those things are out there?
We can see all those galaxies, suns etc. With our telescopes on earth and especially with the two space telescopes that are in orbit around earth. The Webb space telescope and the Hubble space telescope.
We can see all those things. Hence: OBSERVABLE universe.
It is enough to SEE that all. We don't need to send somebody or something with a space ship up there to SEE all those things and know about all those things.

[YetiUprising]

10:27 you are thinking about it in the reverse way of what happens. We don't need to send things out there the universe sends light everywhere. We know how big the "observable universe" is because we made satellites that are designed to pick up the oldest, furthest traveled light waves. We can literally observe them.

EDIT: The Voyager 1 space probe they talked about in the beginning is the furthest manmade object we've ever sent into space.

[JRush]

You should watch Fun to Imagine with Richard Feynman. His QED lectures are amazing too. The book goes into more detail.

[nickdoe]

How do we know?

The light from all these distant stars and planets is travelling to us, so we just have to look at it. We know a lot about how light behaves by doing experiments here on earth.

What they're made of:
Light has wavelengths. Red light is somewhere around 600 nanometers, for example. White light is made up of all wavelengths, which is why sunlight splits into a rainbow when it gets diffracted by a rain drop (different wavelengths of light bend differently). When you shine light through each of the different elements (Hydrogen, Helium, Boron, everything in the periodic table of elements) and measure it on the other side, some wavelengths get absorbed while some make it through, depending on the element. So each element has a unique 'fingerprint' pattern that we can see in the light. This is how we can tell what each star is made up of (how much hydrogen it has, how much helium, etc)

Relative motion:
So we can see the fingerprint patterns on the light for each element coming from each star. But the thing is, those patterns are generally not where you would see them on earth. They are shifted either up or down a couple wavelengths, but you can still see the same patterns. This is because of the Doppler Effect, which happens with waves. If you've ever seen an ambulance drive by, you hear the siren start off higher pitch, then as it drives by you and into the distance, it becomes lower pitch. This is because as the sound wave is travelling towards you, it gets scrunched up since the ambulance source is also moving, and the sound wave gets stretched out and therefore lower pitch when the ambulance is driving away. Because light is also a wave, the same thing happens to the fingerprint patterns of each of the elements coming from the stars. If the patterns are shifted one way, we know the star is travelling towards us, if it's shifted the other way, it's travelling away from us.

Distance:
This is actually the hardest one. There are two methods: first, you take note of where a star is in the sky in, say, January. Then look again in July. After 6 months, earth will be on the other side of the sun. Then you look at the tiny bit the star moved positions in the sky. You're basically drawing a big skinny triangle between the star, the earth in January, and the earth in July. This is called the Parallax method (if you think about it, this is also how your two eyes provide you with depth perception: your brain is constantly drawing a triangle between your two eyes and the thing you're looking at and figuring out how far away it is based on that info)
The second method is called the Standard Candle. So again, we know how light behaves based on doing experiments here on earth. One relationship is how bright something is with how far away it is. If you buy a lightbulb at the store and you know how bright it's supposed to be, you can calculate easily how bright it should look from, say 10 meters or something. Based on observations, we know how bright a certain type of star explosion (called a super nova, when a star 'dies') is supposed to be. So if we see one of these super novas happening somewhere, we can calculate how far away it and nearby things are.

[dakota]

In The Martian movie the time delay for communication is there.
Scientists can see all of this with telescopes, with the deepest viewing telescopes are in space.

[ahsoka]

You can actually see a real picture of a group of 10000 plus galaxies in one picture (a small cluster) type in "Hubble deep field photo" all the lights you see in that photo no how small or miniscule they may seem are all galaxies. When they took this picture I think I read that the size of the area they photographed was the equivalent of holding out a pin needle at arms length.

[DavidGigg]

How did they discover this?

We don't need to send probes, that's what Scientists known as Astronomers do with telescopes and radio telescopes. It is knowledge built up over hundreds of years. eg Galaxies outside of our own were only discovered about a hundred years ago.

[TrojanThugMusic]

It's not that far to the moon? 160 days of driving, non stop, doing 60mph? That's far! Of course in cosmic terms, it's nothing

[TrumpFanClubDeutschland]

Check out "Timelapse of the Future" by the channel Melodysheep or some videos from the channel "Kurzgesagt - In a Nutshell"

[markmuller]

Scientists actually agree with you, the chances for alien life and alien civilization to exist in our universe are extremely high due to the sheer number of stars and planets

[leonardigno]

first of all it is clear that there are 2 possibilities or life forms are very rare or at least 1 solar system in 100 has life forms, so it is difficult if not impossible to be the only life forms in the universe but it also depends on what you consider a life form a bacterium it's alive but it's not complex like us, and the fact that we're certainly not alone makes you think a bit when Europeans arrived in America they brought new diseases with them, so a form of life more evolved than us could bring unknown diseases to us 😅I would prefer that we learn lessons from the mistakes of the past and not repeat them .

[williamwood]

If God works in mysterious ways, why can't people believe that God created everything naturally. The laws of nature control everything. Even we were put on this earth naturally, contrary to popular beliefs.

[strategicthinker]

It's true, The Martian (a fictional story in a film) is right and this educational video is wrong.

[kenmahoney]

As someone who was alive at the time we first landed on the moon, i can honestly say that America didn't land on the moon. Humans did. Yes an American was first. But that man was representing all of man.