general relativity for babies

Georges Lemaître navigated a challenging journey🧗🏻‍♀️ in birthing and establishing the Big Bang theory. Read on this post to discover how strewn his path was and the skepticism and resistance🤨 that he had to face to put forth his work. Join us on our monthly series - Big Bang Theory and cater to your curiosity about our cosmos🌌.

📸Image credits:

Image 1: Georges Lemaitre by Betmann

Image 2: Young Lemaitre by Jean-Pierre Luminet, e-luminesciences blog

Image 3: Arthur Edington by George Grantham Bain Collection, Wikimedia

Image 4: Georges Lemaitre teaching by Encyclopædia Britannica

Image 5: Edwin Hubble by Margaret Bourke - White/Time & Life Pictures/ Getty Images

Image 6: Singularity by Rone Kelly, Astronomy

Image 7: Pope pius xii by Michael Pitcairn

“ About Tachyons “ // Physicsgene

Hello hello! I was wondering if you could explain to me about black stars? (Sorry if this comes off as bossy!) It's just that I read in a book that they're the stars that are on the brink of dying and someone else (whom I do not think is that much of a reliable source) says they don't exist or that they're black holes, I would not be inclined to believe them, but books *do* get outdated so.. thank you so much if you can satiate my curiosity!

hello anon! i’d never heard of black stars before, so i did a bit of research. something important to note with this information is that i couldn’t find an article or study more recent than 2013, and with how fast astrophysics and cosmology have been changing, it’s likely that these are out of date, so take everything stated here with a grain of salt.

from my understanding, black stars are a theoretical alternative to black holes, utilizing semiclassical general relativity, as opposed to classical general relativity which says that black holes should exist.

the main study i was reading had a bunch of jargon i couldn’t fully understand, but seemingly, the main difference between black stars and black holes are that black stars don’t have to have an event horizon (in a black hole, the event horizon is the “point of no return,” or the point at which the escape velocity is so high it surpasses the speed of light).

another thing i read was that black stars don’t/wouldn’t have a singularity. this would be caused by quantum processes within the star creating degeneracy pressure (think: pressure between subatomic particles), which would prevent the particles within the star from occupying the same point in space and forming a singularity. this lack of a singularity would make it so light can escape the black star, but would be extremely warped and redshifted. this would solve the question of how information can be destroyed in black holes, but again, is very theoretical.

black stars could also be an in-between phase between a red supergiant and it’s collapse into singularity (forming a black hole), which may have been what you were referring to by saying “stars on the brink of dying.”

i would, however, take this all with a grain of salt as i mentioned earlier. these studies are from over 10 years ago, and a lot has changed since then (including actually imaging black holes!), which, as black stars seem to be an alternative to black holes given some inconsistencies in our knowledge, the fact that we’ve imaged black holes makes it more unlikely that they’re real.

i hope that answered your question, if not, feel free to comment or send another ask :)

sources:

Willem de Sitter – Scientist of the Day

Willem de Sitter, a Dutch mathematician and astronomer, died Nov. 20, 1934, at age 62. 

read more...

holy fuck someone is claiming they finally broke physics

i’ve been waiting for this moment for a long long time… ✨

bad tropes

I have so much trouble enjoying science fiction and historical fiction nowadays. My stupid college education is getting in the way. things that go through my head:

-no, you can’t harvest zero-point energy from a vacuum; you need an energy gradient to do that.

-wormholes are supposed to be spheres

-no, aliens did not build the pyramids for goodness sake

-no, the church did not declare science heretical in the middle ages

-why is the middle east just a big desert in this?

-if you converted somebody’s body into energy to teleport them, you would literally just be killing and cloning them; not to mention that you would essentially be turning them into a nuclear bomb. Also, perfectly recording that information is basically impossible because of the uncertainty principle

-while on the topic of star trek, I feel like that franchise takes the prize for “the most hilariously unrealistic and over-optimistic depiction of a space-faring civilization in fiction”.

-why is everyone breaking formation in this medieval battlefield? and where are all the pikes?

-that... is not how people dressed back then in that region.

-no, hyperspace isn’t white

-just... everything about “pym particles” and the “quantum realm” in marvel

-*sigh* no, the inquisition was not burning witches in the middle ages.

-stop calling it the dark ages, I BEG you

-nobody takes conservation of mass seriously

-no, making objects and creatures out of “pure energy” isn’t a thing

-ninjas refusing to use guns because “honor” LOL what the fuck they’re ASSASSINS

Today's eclipse science: The Eddington experiment! By measuring the position of stars near the sun that are not usually visible due to its light, compared to their typically observed position, it can be proven that the gravity of the sun bends light when it passes!

the greatest theories in physics: a visual thread by @PhysInHistory on twitter (with alt text) (part 1) (part 2 will be in reblogs)

image one: black unserifed text on white background, saying "the greatest theories in physics", with "greatest in manuscript handwriting style, and "physics" in bold. below this text, there is very small writing saying "a visual thread", also black, but the text has serifs. in the background there are equations and calculations, also in black font, but much thinner and smaller.

image two: on the right side of the image, there is a coloured photo of half of isaac newton's face and a bit of his shoulders. on the left side, there is large black unserifed text on white background, with large handwriting at the top saying "newtonian mechanics". "mechanics" is in bold. below, it says (in smaller black serifed writing) "isaac newton (1642 to 1727) formulated the laws of motion and universal gravitation, which describe the motion of objects under the influence of forces. newton's theory was able to explain many phenomena, such as the orbits of planets, the tides, and the motion of projectiles. newton's theory also laid the foundation for classical mechanics, which is still used to study the motion of macroscopic objects."

image three: at the top of the photo, there is large black capitalised thin unserifed writing saying "electromagnetism", and from the bottom of the text to around the middle of the image, there are images and equations, including a circuit diagram. in the bottom left, between the bottom of the image and the hypothetical horizontal middle line, there is a black and white image of james clerk maxwell. around the bottom right, there is black serifed text saying "james clerk maxwell (1831 to 1879) unified the theories of electricity and magnetism, which describe how electric charges and current produce electric and magnetic fields, and how these fields interact with each other. maxwell's theory also predicts the existence of electromagnetic waves, such as [visible] light, radio waves, and X-rays, which travel at a constant speed in a vacuum"

image four: at the top of the image, there is large bold capitalised black unserifed writing, saying "thermodynamics". at the mid to bottom right, there is a black and white image of ludwig boltzmann. under the large unserifed text, and next to ludwig boltzmann, there is small black serifed text, saying "thermodynamics defines concepts, such as temperature, entropy, and free energy, which are useful for studying the efficiency of engines, the direction of spontaneous processes, and the equilibrium state of systems. physicists such as sadi carnot (1796 to 1832), rudolph clausius (1822 to 1888), william thompson (lord kelvin) (1824 to 1907), and ludwig boltzmann (1844 to 1906), developed the laws of thermodynamics, which describe how heat and work are exchanged between systems and their surroundings"

image five: the background of the image is cream coloured, with the equation "E equals m c squared, all over root one minus v squared over c squared" and some other writing. in the bottom left corner, there is a black and white image of albert einstein. at the top of the image, there is bold large unserifed black writing saying "special relativity", which is directly against the cream background. below the writing, there is a white box, containing small black serifed text, which says "albert einstein (1879 to 1955) proposed the theory of special relativity, which describes how space and time are relative to the state of motion of an observer. special relativity also implies that mass and energy are equivalent, as expressed by the famous equation E = m c squared. special relativity revolutionized our understanding of space and time, and resolved some paradoxes that arose from applying Newton's theory to objects moving at very high speeds"

image six: this image has a background of grey-brown paper with small squares on it, as what one would would see in a maths exercise book. the paper has differential equations on it. like the previous image, there is a black and white image of albert einstein in the bottom left corner. at the top, there is a dark brown box, containing large white bold unserifed letters saying "general relativity". the writing below is directly against the paper but above the differential equations. it is white. in large bold unserifed text, it says "albert einstein". below that, it says (in smalled serifed text) "also proposed the theory of general relativity, which describes how gravity is not a force, but a consequence of the curvature of space and time caused by mass and energy. general relativity predicts phenomenona, such as gravitational lensing, gravitational redshift, gravitational waves, and black holes. general relativity also provide the framework for studying the origin and evolution of the universe"

(end of alt text, please check reblogs for more images and alt text)

MAY 12, 2022

The highest-resolution image ever taken toward Sgr A*, the supermassive black hole in the center of our Milky Way galaxy. The ring of light is from hot material swirling around it. The black hole itself cannot be seen, but it swallows light itself, so we see a dark void in the center of the ring

Nice write-up on it by Phil. Looks a lot like the black hole in M87 that this team imaged before, but it's way smaller.

One easy way to confirm Einstein’s theory is to use the GPS system on your cell phone. The GPS system consists of thirty-one satellites orbiting the Earth. At any time, your cell phone can receive signals from three of them. Each of these three satellites is moving in a slightly different trajectory and angle. The computer in your cell phone then analyzes this data from the three satellites and triangulates your precise position. The GPS system is so accurate that it has to take tiny corrections from both special and general relativity into account. Since the satellites are moving at roughly 17,000 miles per hour, a clock in the GPS satellites beats slightly slower those than on Earth due to special relativity, which states that higher speeds result in slower time—the phenomenon demonstrated in Einstein’s thought experiment of outracing a light beam. But since gravity is weaker the farther you move into outer space, time actually speeds up a bit due to general relativity, which states that space-time can be warped by gravitational pull—the weaker the gravitational pull, the faster time moves. This means that special and general relativity work in opposite directions, with special relativity causing the signals to slow down, while general relativity causes the signals to speed up. Your cell phone then factors in both competing effects and tells you precisely where you are located. So without special and general relativity working in tandem, you would be lost.

From the tiniest atoms⚛️ to the vastness of galaxies☄️, ever stopped and wondered what sparked it all?🤔 Well, we did dig a bit deep into it and here we are to walk you through what we found. 🔭Join us in this monthly series to unravel the greatest enigmas of our shared universe. Let's explore the cosmos together!🚀

Currently watching This Video Essay From acollierastro

and Did You Know that we designed an array of radio telescopes called The Event Horizon Telescope which 1)can take pictures of blackholes and 2)is the size of THE EARTH?!?!

cuz that's pretty fuckin sweet owo

Science is So Cool :3 :3

i have a question about the age of the universe:

i was reading a book on cosmology this afternoon and it started talking about general relativity, and it got me thinking: if time is relative, is the universe older in some places than in others? the universe is about 13.6 billion years old for us, but would it be younger for a planet orbiting a black hole, where time moves slower due to time dilation?

or would its age be the same throughout the universe because the speed of light (and thus how we observe everything in the universe) is constant no matter where you are or how you’re accelerating?

i might be completely overthinking this, but i’m giving myself a headache trying to work this out on my own and was wondering if anyone would be willing to explain it.