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Sophia Gad-Nasr Profile picture
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14 Aug, 4 tweets, 1 min read
Ever wonder how many photons have been emitted over the Universe's history? Probably not, BUT YOU DO NOW: the total # of photons ever emitted is 10⁸⁹, ie,
100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000. 🤯
By the way, they're dominated by photons from the Cosmic Microwave Background. All photons from other processes make up such a tiny amount compared to this! Here's how you can figure it out: there are ~410 photons/cm³, and the Universe is ~46 billion light years in radius. 🙂
Ooooo this set some people on 🔥 lol! Happy Saturday!
And one more thing: as the second tweet suggests, this is in our observable Universe, as don't know the size of the actual Universe!

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More from @Astropartigirl

Sophia Gad-Nasr Profile picture
24 Jul
Today is astronomer and trailblazer Vera Rubin's birthday. In 1965, she became the first woman to enter Palomar observatory, where she made the groundbreaking discovery of dark matter in Andromeda via its gravitational interactions with Kent Ford. #BirthdayVeraRubin (1/n)
Fritz Zwicky inferred its existence in 1930s in the Coma cluster using the virial theorem, but highly overestimated the dark matter content. Vera Rubin definitively proved dark matter exists; her calculations are still relevant today. Dark Matter Queen. #BirthdayVeraRubin (2/n)
In 2011, when physicists won the Nobel Prize in Physics for discovering dark energy, stuff that's causing the Universe's expansion to accelerate w/ time, I was sure Vera Rubin was next! After all, we understand dark energy far less than we do dark matter. #BirthdayVeraRubin (3/n)
Read 9 tweets
Sophia Gad-Nasr Profile picture
14 Jul
This q stems from a common misconception that we're at the center of the Universe. Let's clear that up: from our position in the Universe, light from the Cosmic Microwave Background (CMB), a relic of the Big Bang, took ~13.8 billion yrs to get to us from all directions. (1/n)
A galaxy 5 billion light yrs away is one we see *as it was* 5 billion yrs ago, because light has a finite constant speed in vacuum (space is a VERY nearly a vacuum). Now let's look at the perspective of an intelligent being in that galaxy that's 5 billion light years away. (2/n)
That being, when they look at our galaxy, the Milky Way, will see our galaxy as we can never see it: they see it as it was 5 billion years ago!! And from their perspective, the light from the CMB took 13.8 billion yrs to reach them, from all directions. (3/n)
Read 10 tweets
Sophia Gad-Nasr Profile picture
24 Mar
This is the supermassive black hole in M87, silhouetted against swirling gas it'll either eat, or expunge in jets. The lines are the magnetic field that powers the jets that shoot gas thousands light-years out of the galaxy. Incredible.
The SMBH in M87 is 55 million ly away. You'd have to cram 6.5 BILLION Suns into a diameter ~30,000 times that of the Sun to make one like it. For context: its event horizon is 120 AU, swallowing the entire solar system. But bc it spins, anything within 700 AU of the Sun is toast.
And in case you are wondering what 1 AU is, that's 1 Astronomical Unit, which is the distance of the Earth from the Sun. So saying "120 AU" is like saying something is 120 times the Earth-Sun distance wide/far/long/etc. And 1 AU is about 150 million km. Nothing too big 🙃
Read 14 tweets
Sophia Gad-Nasr Profile picture
11 Mar
I know people mean well when they do this, but the "just ignore them" responses to victims of online abuse actually ENABLES THE ABUSERS and is DESTRUCTIVE TO VICTIMS OF ONLINE ABUSE.
You are creating a safe bubble for trolls by trying to convince those hurt by them to give them a pass. I get that's not what you intend, but that's the result. Please don't do this.
By doing this, you are also putting the blame on the victim, because you're saying "it's your fault because you let it get to you". No, it's NOT my fault that someone chose to target me for no reason and I WILL NOT TAKE THE RESPONSIBILITY OF THE ABUSER. THANK YOU.
Read 6 tweets
Sophia Gad-Nasr Profile picture
25 Feb
|￣￣￣￣￣￣￣￣|
| GENDER IS |
| A SPECTRUM |
|＿＿＿＿＿＿＿＿|
(\__/) ||
(•ㅅ•) ||
/ 　 づ
It doesn't take a lot of effort to support people's right to be themselves. It does take a lot of effort to be hateful.
Every time I tweet about this my followers drop like flies. So I'm gonna lay this out:
I support freedom of gender identity
I believe Black Lives Matter
I stand against sexism and racism
I stand against Antisemitism
I stand against Islamophobia
I believe in freedom of choice
Read 5 tweets
Sophia Gad-Nasr Profile picture
6 Feb
Yeah dude I just HATE knowing how things work! Who the fuck CARES how the Universe will die, or that we don't understand 95% of it SO WHAT. I hate the Universe. And apparently myself since I AM a physicist who's also a woman. GASP. 🙄
Oh Saturn has a hexagon shadow going because of the physics of fluid and shit? SO WHAT. HOW BORING. (NOT)

Amazing work by the wonderful @JPMajor (oops i mean NOT amazing, I'm a woman and therefore in hate this! 🤦‍♀️)
Oh, and the Universe looks like a cosmic web because of the way that stupid boring stuff you call "dark matter" decided to orient itself and so the stuff we can see fell towards it, because of literally THE MOST BORING THING EVER: PHYSICS?! Pshhhh
(From Millennium Simulation)
Read 10 tweets

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