Sophia Gad-Nasr Profile picture
I do cosmology and astroparticle theory. I pick apart the Universe to figure out how it works. Science Advisor. Dark Matter hunter. 🇵🇱✡️🇪🇬☪️ She/her
kiddphunk Profile picture AlgoCompSynth by znmeb Profile picture Darrel Mc. 🇦🇺 🌻 (💉💉+💉) MSc - 🔭🌃🪐🚉 Profile picture ⭐Dr.Watson📚 Profile picture 4 added to My Authors
Mar 24 6 tweets 2 min read
The Universe is BIG. HUGE. But we don't actually know HOW huge--it may even be infinite. But because the expansion of the Universe is Accelerating, some parts of the Universe are so far away that light can never reach us. THERE ARE PARTS OF THE UNIVERSE THAT WE CAN NEVER OBSERVE! No matter how good our technology gets, we'll never be able to build a telescope that can resolve anything beyond what we call the "observable Universe" because light from objects beyond this point will not have had enough time to reach us. They're forever beyond our reach!
Sep 21, 2021 5 tweets 2 min read
Since I'm losing followers for caring how my name is spelt, here's why it matters:
I'm an astrophysics PhD candidate, ie expert. @jubileemedia elicited my expertise. I gave them an entire day. I was not paid, or adequately fed. I DESERVE MY EXPERTISE TO BE ATTRIBUTED TO MY NAME. My name is "Sophia", not "Sofia". Or "Soph", or "Sophie", or any other variation. SOPHIA. If you forget, you'll find my name in my email, signature, even my social media bios! There's no excuse to take my expertise for free, not feed me a proper lunch, and then misspell my name.
Sep 21, 2021 8 tweets 3 min read
Update: I emailed my point of contact at @jubileemedia asking to have my name fixed. It might seem small, but I gave half a day of my life for this episode, one I could've spent on my PhD work. The least I deserve is being respectfully addressed with my name correctly spelled.
Aug 14, 2021 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. 🙂
Jul 24, 2021 9 tweets 4 min read
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)
Jul 14, 2021 10 tweets 3 min read
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)
Mar 24, 2021 14 tweets 4 min read
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.
Mar 11, 2021 6 tweets 2 min read
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.
Feb 25, 2021 5 tweets 1 min read
| ̄ ̄ ̄ ̄ ̄ ̄ ̄ ̄|
| 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.
Feb 6, 2021 10 tweets 5 min read
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! 🤦‍♀️)
Aug 8, 2020 41 tweets 10 min read
Just learned of cliquey exclusionary stuff going on where specific accounts were boosted for followers, and others left in the dust. Some personally hurt. I'm one of the scicommers "left in the dust", had no idea, but here are my thoughts since I'm part of "Science Twitter": I wanted you all to know I had no idea, was not included in the group. I worked VERY hard on my following with my scicomm for years, with no luxury of a group boosting me. I DID notice accounts (that happen to be part of this fiasco) gain a significant following.
Jul 10, 2020 7 tweets 2 min read
If you touch two CLEAN blocks of the same metal together in space, they weld!
Atoms in solid metals move a bit. Touch two clean surfaces together, and the atoms can't tell they're in different blocks so they become one group of atoms, ie ONE SOLID.
(Gif: homemadetools.net/forum/cold-wel…) The reason it doesn't happen on Earth when you put two of the same metals together is because of oxygen, which causes metal to rust. That oxide layer sits the two metal surfaces, so atoms in each block see a layer of different atoms, and know that's their "limit" for movement.
May 28, 2020 10 tweets 2 min read
"If dark matter exists, why can't we see its effects in the solar system?" is a question I'm often asked. The answer: compared to the mass of the Sun, the mass of dark matter in our solar system is far too little to affect planet orbits like it does stars in galaxies. Here's how: The solar system is big--REALLY big--from our perspective. But it's a tiny speck on the galactic scale. We can *very roughly* say there's ~1 star per pc³ in the galaxy (1 pc = 3.26 light-years). To compare, our solar system is ~100 AU in radius, which is only about 0.0005 pc.
Jan 3, 2020 18 tweets 5 min read
Lise Meitner
Vera Rubin
Jocelyn Bell Burnell
Chien-Shiung Wu
Cecilia Payne
Rosalind Franklin

The list goes on. And the Nobel Prize committee still won't admit sexism is why there have been 3 women to win in physics, and 5 in chemistry, EVER. Great start to 2020 with this one. Of 212 Nobel Laureates in Physics (one man was awarded *twice*, btw), 3 have been women = 1.4% Nobel Laureates in Physics are women.

Of 184 Nobel Laureates in Chemistry, 5 went to women = 2.7% Nobel Laureates in Chemistry are women.

The numbers speak for themselves, friends.
Nov 1, 2019 11 tweets 3 min read
Fun fact: the circumference of a circle in our spatially flat Universe is 2πr. But if our Universe was positively curved (think the surface of a sphere), it's *less than* 2πr. If negatively curved, like a saddle or pringles chip for example, it's *greater than* 2πr! It makes sense too if you picture it: on a sphere, the circumference of a circle of the same radius as a circle on flat space will be smaller because the sphere curves inward, making the path you travel that circle to be shorter than the one on a flat sheet of paper.
Oct 8, 2019 11 tweets 2 min read
The Nobel Prize in Physics awarded was very well-deserved. However, next time you hear Vera Rubin didn't win for discovering dark matter bc *insert excuse here*, let today show exactly why she didn't win for discovering one of cosmology's most pressing questions: she was a woman. Today, countless physicists and astronomers chug away at trying to figure out what dark matter is. Myself included. We all owe part of our curiosity and drive to Vera Rubin. Vera Rubin. Remember her: Vera Rubin. Because she's why you do what you do. And she didn't win the Nobel.
Sep 11, 2019 16 tweets 4 min read
On 9/11 Arabs and anyone who looked Muslim realized how alone were. We couldn't come together with you and just mourn because the world turned against us and forced us to explain ourselves for something we didn't even understand. That's what 9/11 was like for us thanks for asking And the worst part is that talking about our experience is always something frightening because we fear that you will turn to us and tell us we're ignorant and insensitive, so we keep it in.
Aug 20, 2019 37 tweets 7 min read
An interesting fact about my research on Self-interacting dark matter (SIDM) is that this type of particle dark matter requires a velocity-dependent cross-section to explain observations on both small and large scales. Now, let's unpack what all this jargon actually means! The standard paradigm of dark matter, the type that successfully explains everything we see in the Universe today, like the things encoded in the Cosmic Microwave Background that tell us about dark matter, large-scale structure like clusters of galaxies, is Cold Dark Matter (CDM)
Jun 25, 2019 19 tweets 4 min read
"Are dark matter and dark energy related?" is a common question I get. Here's the deal: the *only* way dark matter and dark energy are related is that they both have "dark" in their names, which is a placeholder for things we can't see and don't understand. Dark matter is stuff, that, like regular matter, is most likely made of subatomic particles, but ones that have yet to be discovered. There's about 5 times more dark matter than there is regular matter in the Universe, making it the most dominant form of matter.
May 8, 2019 15 tweets 4 min read
Galaxy clusters are giant structures of up to *thousands* of gravitationally bound galaxies. Of order 10¹⁵ times the mass of the sun, they curve spacetime so much that they act as gravitational lenses, producing arced images of galaxies that lie far more distant behind them. 1/ These beasts provide direct evidence of Einstein's Theory of General Relativity, revealing how mass curves spacetime by bending the trajectories of photons emitted by objects far behind them, producing the galaxy arcs you see in the above image. 2/
Feb 5, 2019 4 tweets 1 min read
Professors: the way you talk to your students matters. By telling your class you expect they learned something prior to taking your class, you *literally* create a learning block that will prevent them from asking important questions from fear of embarrassment. DO NOT DO THIS. The moment your students feel embarrassed to ask questions because *you* made them feel they should already know something they were not taught, or were not taught well, or even could not grasp at the time for whatever reason, you have failed them as a professor.