BC SCIENCE
Saved by @jacobhtml

1/ Today is #BlackHoleFriday, an annual science outreach event that, by complete coincidence I’m sure, is done on #BlackFriday. You’ll read lots of cool stuff about black holes on the hashtag. Here’s mine.

 2/ Black holes are weird. Duh. People like to think of them as something like incredibly dense nuggets of stuff that sucks other stuff in. But they’re not like that.
3/ If you squeeze enough mass into a small enough volume, the gravity gets so intense that it’s impossible to escape them *if you get too close*. From far away, though, gravitationally they more or less act like anything with that much mass.
4/ So if the Sun turns into a black hole we wouldn’t get drawn in. In fact, we’d orbit it almost exactly the same way as we do now, though we’d freeze to death pretty rapidly, which, in the end, would still kinda suck.
5/ Black holes get weird *when you get close*. Anything with mass warps space — we feel that warp as gravity! — but black holes stretch space to its limit.
6/ It’s like falling down an infinitely deep hole with perfectly vertical and frictionless sides. Down you go, and that’s that. Even light can’t get out if it gets too close.
7/ But because they warp space so much, there are weird effects. Take, for example, the size of a black hole. Imagine an infinitely deep circular hole in the ground. Literally bottomless. What’s the hole’s radius?
8/ Well, if you walk around it it has a circumference. Divide by 2 pi and you get the radius. But now try to go *through* it, down the hole and back up. You’d have to travel forever. The radius in that sense is ∞.
9/ I know, right? It gets weirder. A black hole in general is a sphere. That means you can measure the radius by going around it. How does that depend on mass?
10/ Turns out, if you double the mass of a black hole, you double the radius (see: https://t.co/jIYeYG3THl). That’s the way the math works out. BUT think about geometry. The volume of a sphere goes up as the radius CUBED.
11/ So when you double the mass of a black hole, the volume goes up by 2 x 2 x 2 = 8 times. That leads to an interesting idea. Density is mass / volume. What happens to a black hole’s overall density as it consumes material?
12/ Double the mass and the volume goes up by 8. That means the density goes DOWN by 2/8 = a factor of 4. As a black hole gets more massive *its density gets lower*. 10 times the mass = 1/100th the density.
13/ At some point a black hole gets so big its density becomes very small. A black hole with 4 billion times the Sun’s mass would have a diameter of 24 billion km (big!) but have the density of… air.
14/ In other words, if you took a sphere 24 billion km across and filled it with *air* at Earth’s sea level density, it would be so massive it would be a black hole.
15/ Mind you, we see some black holes this massive! They’re in the centers of distant galaxies, but still. They exist. Supermassive, but very low density.
16/ Come to think of it, they’d float if you had a bathtub big enough. And could keep the water from collapsing into a black hole. And had a uniform 1g gravitational field under it to counteract buoyancy. Hmm. This idea has issues. I’ll have to write more about it some day.
17/ Anyway, I had a conversation with a leading black hole physicist some years ago, and mentioned this to him. He got thoughtful, and then nodded. “Yeah,” he said. “That’s right!” I was pretty chuffed to a) be right, and 2) have thought of something he hadn’t thought of.
18/18 Honestly, I wondered if I had missed something obvious, but nope. This is correct. So, to summarize: Black holes are weird. And that’s my #BlackHoleFriday thread. /fin
19/18 (yeah, I know) BTW here’s my Crash Course Astronomy episode on black holes.

https://t.co/QetnodyE72

#BlackHoleFriday

More from Science

Marit Kolby Zin\xf6cker
Marit Kolby Zinöcker...
@zinocker
Did we get dietary saturated fats all wrong? The #HADLmodel provides a new understanding and an opportunity to get it right. THREAD👇👇👇
@simondankel @kariannesve

Increased dietary saturated fatty acids lead to increased cholesterol in lipoproteins, but we don’t know why. Enter the #HADLmodel, which explains changes in lipoprotein cholesterol as adaptive homeostatic adjustments that ensure optimal cell membrane fluidity and cell function.

We propose that circulating lipoproteins enable appropriate redistribution of cholesterol molecules between specific cells and tissues, to accomodate changes in dietary fatty acid supply, due to our omnivore nature and variable intake of fatty acids. #HADLmodel

Our #HADLmodel implies that circulating levels of LDL change for protective, not for pathological reasons; an SFA-induced raise in LDL cholesterol in healthy individuals is a normal response, while a lack of this needed response may reflect a deeper pathology in lipid handling.

Circulating lipoproteins may change for pathological reasons, when regulatory mechanisms become disrupted by pathogenic processes related e.g. to inflammatory processes. Diverging lipoprotein responses in healthy versus metabolically unhealthy individuals support this view.
SCIENCE
10-K Diver
10-K Diver
@10kdiver
1/

Get a cup of coffee.

In this thread, we'll cover *State Quantities* and *Flow Quantities*.

This mental model can help us analyze many different entities -- from complex engineering systems to publicly traded companies.


2/

A "State Quantity" is something that's associated with a *specific point in time*.

For example, the number of followers a Twitter account has is a state quantity. This number can go up and down over time. But at any one *specific* time point, it's fixed.

3/

Similarly, the amount of cash a company has is a state quantity.

This cash balance can also rise and fall over time.

But pick any one *specific* time point -- and the company can only have one *specific* cash balance at that time point.

4/

By contrast, a "Flow Quantity" is something that's associated with a time *interval* rather than a time *point*.

For example, the number of followers gained by a Twitter account is a flow quantity. It's meaningful only when we specify a time interval (eg, the last 30 days).

5/

A simple analogy is that a State Quantity is like a photo -- a snapshot at a particular *point* in time.

But a Flow Quantity is like a video -- a record of events that take place during a particular time *interval*.
SCIENCE , FINANCE
Advertisement
Shrey Srivastava
Shrey Srivastava
@BlogShrey
#DDDD $LBPS $LOAC

A thread on the potential near term catalysts behind why I have increased my position in 4d Pharma @4dpharmaplc (LON: #DDDD):


1) NASDAQ listing. This is the most obvious.

The idea behind this is that the huge pool of capital and institutional interest in the NASDAQ will enable a higher per-share valuation for #DDDD than was achievable in the UK.

Comparators to @4dpharmaplc #DDDD (market capitalisation £150m) on the NASDAQ and their market capitalisation:

Seres Therapeutics: $2.33bn = £1.72bn (has had a successful phase 3 C. difficile trial); from my previous research (below) the chance of #DDDD achieving this at least once is at least


Kaleido Biosciences: $347m = £256m. 4 products under consideration, compared to #DDDD's potential 16. When you view @4dpharmaplc's 1000+ patents and AI-driven MicroRx platform (not to mention their end-to-end manufacturing capability), 4d's undervaluation is clear.
SCIENCE
JS Oakie\U0001f4dcProtect the 4th Amendment.
JS Oakie📜Protect the 4...
@OakieJs
I think we have to expand our thinking about the toroidal sphere even more. When looking at maps, I noticed the da Vinci map, from 1514, which uses the Reuleaux Triangle. This triangle is formed from 3 intersecting circles, and is in the center of a trefoil.


The trefoil is the focal point in many gothic structures, repeatedly and prominently shown. It is represented in many ways. ‘Going down the rabbit hole’ now makes sense, if you understand the center point of the ears is the center of the torus, with the rabbit trefoil.


The trefoil can be found within the toroidal field. Here is a fun site, where you can manipulate it yourself. https://t.co/FCMcybuuFC


The wiki page makes it seem like there isn’t much of importance with the Reuleaux Triangle, besides being used for coinage, or some stupid bike. But the Wankel engine is an interesting engine, using this geometric design https://t.co/ayPOgkAqGN


https://t.co/m9EaWwF796
SCIENCE
Michael Adebayo \U0001f1f3\U0001f1ec\U0001f1eb\U0001f1f7
Michael Adebayo 🇳🇬🇫🇷...
@MichAdebayo
Wonder why your Ph.D./Master's application is being rejected?

Here are some insider reasons (from a committee member) that result in such "Love Letters" 👇

- A Short Thread

1) First, you should know that sometimes, an independent reviewer is required (especially in the US) to review applications even after PIs must have selected their candidates. So, even if any bias slips through the PI, the independent reviewer will pick it up.

2) Having said this, there are three major issues that application reviewers/committees often find with your application. These three components make your applications almost challenging to assess.

3) NUMBER ONE - Incomplete Applications

This occurs when you do not upload the requested documents needed to evaluate your file. Think of a candidate that did not send a GRE score when the institution clearly requires it for admission.

4) NUMBER TWO - Error laden Essays

This is particularly interesting because based on reports from this resource person, it is not particularly about how little your experience is but how you communicate it error-free or at least extensively minimized. This gives headache!
SCIENCE

You May Also Like

Adam McKay
Adam McKay
@GhostPanther
1) My Stan Lee story happened when I was in 5th grade. I was visiting NYC with my Dad and had read the address for Marvel in the comics I read constantly. I begged my Dad to take me and to his credit he did. And guess what? It was just an office.

2) We were down in the lobby and I was kind of crushed. I don’t know what I expected, The Thing and the Yancy Street Gang to be sitting around smoking cigars? Anyway, my Dad was taking a beat to figure where we were going next and a guy came up to us.

3) He was wearing a white shirt and tie and said to Dad “Is he disappointed because. The Marvel offices were just offices?” My Dad said yes and then the guy who had gray around his temples and a mustache said “hold on a second” and opened one of those office mailboxes with a key.

4) He then handed me a thick stack of EVERY SINGLE MARVEL COMIC COMING OUT THE NEXT MONTH. “Here you go. Keep reading Marvel comics” he said and then walked off. I left in a daze and about 15 minutes later it hit me “Gray around the temples, mustache... That was Stan Lee!”

5) Later when I wrote on the Ant Man movie I told Kevin Feige the story, the year, look of the guy etc and Kevin said “That’s exactly the kind of thing Stan would do and he would have been there then. That was him.” Rest In Peace Stan Lee and thank you for the comics.
CULTURE
libertyandjusticeforall
libertyandjusticeforal...
@Mark923to25
1. #Qanon told us that Saudi Arabia is a central piece of the puzzle in taking out the Deep State...we are watching the Deep State attempt to remove Crown Prince MBS and disrupt Pres Trump's administration's ties with MBS and the "new" Saudi/US coalition. Early in his admin,


2....@Potus sent Jared Kushner (JK) to SA on an undisclosed trip and told King Salman that business as usual was over, and if he wanted Pres Trump's support, Prince Alwaleed would have to be divested of $ and power; Alwaleed is one of top Deep State $ men and was tied to HRC.


3. @Potus knew that before he could begin cleansing the US and the rest of the world of the DS, he would have to cut one of the financial head's off the snake (Alwaleed). After JK met w/ King Salman, Alwaleed was arrested and divested of billions; MBS became leader of SA.


4. SA loves Pres Trump because he's a man of his word; SA could not trust Hussein or Clintons because they use SA for oil and leverage; SA has many factions, but essentially you have the new and upcoming SA that is attempting to modernize through Crown Prince MBS, and then you


5...have the old guard represented by Alwaleed who was one of the Deep State financial heads and loyal to the DS more than SA; SA knew Hussein was financing Iran to hold western world hostage, and SA was caught in middle of Deep State black mail; this is why @Potus was celebrated
ALL
Advertisement
Vibhu Vashisth
Vibhu Vashisth
@VIBHU_Tweet
महाभारत की कहानी कौन नहीं जानता।लेकिन क्या आपको पता है कि महाभारत के ज्यादातर पात्र किसी न किसी श्राप में फंसे थे।अगर ये श्राप न होते तो कदाचित महाभारत की कहानी कुछ और होती।हिन्दु पौराणिक ग्रंथों में विभिन्न श्रापों का वर्णन मिलता है व हर श्राप के पीछे कोई कहानी अवश्य होती है।


आइए आज जानते हैं महाभारत कथा में वर्णित कुछ श्रापों के बारे में।

1) राजा पाण्डु को ऋषि किन्दम का श्राप

एकबार महाराज पाण्डु शिकार खेलने वन गए।झाडियों के पीछे कुछ हिल रहा था। मृग है सोचकर राजा ने बाण चलाया जो जाकर ऋषि किन्दम और उनकी पत्नी को लगा।वे दोनो रति-क्रीड़ा में लिप्त थे।

जब राजा ने उन्हें देखा तो बहुत दुखी हुए कि ये मुझसे क्या पाप हो गया।बहुत क्षमा याचना के बाद भी किन्दम ऋषि ने पाण्डु को श्राप दे दिया कि जब भी वो किसी स्त्री को काम भावना से स्पर्श करेंगे उसी क्षण उनकी मृत्यु हो जाएगी।पश्चाताप करने, वे सिंहासन पे अन्धे राजा धृतराष्ट्र को बैठाकर...


..स्वयं अपनी रानियों कुंती व माद्री के साथ वन चले गए।पांडवों का जन्म भी कुंती को ऋषि दुर्वासा द्वारा दिए गए मंत्र से हुआ था जिसमे किसी भी देव का स्मरण कर उस देव से कुंती,पुत्र प्राप्त कर सकती थी।एक बार माद्री पे मोहित हो जब पांडु ने उसे स्पर्श किया,उसी क्षण पांडु की मृत्यु होगयी।


2) उर्वशी का अर्जुन को श्राप

महाभारत युद्ध से पहले जब अर्जुन दिव्यास्त्र प्राप्त करने स्वर्ग गए तो वहां उर्वशी नाम की अप्सरा उन पर मोहित हो गयी। अर्जुन ने जब उन्हें अपनी माता के समान बताया तो यह सुनकर उर्वशी क्रोधित हो गयी और अर्जुन को श्राप दे डाला कि तुम नपुंसक की भांति...
ALL
Anu Satheesh
Anu Satheesh
@AnuSatheesh5
Thiruvairanikulam Mahadeva Temple
Ernakulam Kerala🚩
#temples

Temple is known as Sabarimala of Women

Thiruvairanikulam Mahadeva Temple is situated on the banks of the Periyar River. Siva Temple has a separate sannidhi for Parvathi Devi which will be open only for 12 days a year


The Nadathurappu Mahothsavam happens every year on Malayalam month of Dhanu. On opening day, a grand procession starting from Akavoor Mana carries the ornaments of Devi to the temple. Swayamvara Archana is the main pooja here to clear the obstacle in marriages.
Legend is that 👇


Vigraham existed in another place called Iranikulam. A Namboodiri of Sreemoolanagaram used to visit the Iranikulam temple regularly. Akavoor Chathan, a boatman will take him to the Iranikulam temple and back. Because of Bhakthi of Namboodiri, Shiva traveled with him to his place.


Akavoor Chathan identified Siva chaitanyam and their family built a temple here. Parvati devi herself will cook Nevidyam here for Shiva, which was witnessed by a priest. Devi was angry at this and decided to leave the place. But when the priest offered his sincere apology👇


Devi blessed him and told that she will be present here 12 days in a year. Thus the period which begins from Thiruvathirai Day in Dhanu is known as the Nadathurappu festival.
Temple Nada opens today night.
Picture credit: Google.
🙏🕉🙏
ALL
Jaya_Upadhyaya
Jaya_Upadhyaya
@Jayalko1
HORANADU ANNAPOORNESHWARI, CHIKMAGALUR (KAR)
#bharatmandir

Annapoorneshwari is the Devi of nutrition and food. The literal meaning of Annapoorneshwari is “Feeding one and all”. Anyone who comes here is offered meals and shelter within the premises.
@LostTemple7


Maharshi Agastya is believed to have done pratishtha here.

Once, Shiva and Parvati had an argument. Shiva declared everything in the world including food to be Maya or illusion. To prove him wrong, Devi Parvati disappeared resulting in entire Earth becoming still.


Taking pity, Devi appeared as Annapoorna and relieved everyone.
Another belief is that once Shiva beheaded Brahma and his skull got stuck in Shiva’s hand. He was cursed that till the skull is not full of food or grains, it will remain stuck to his hands.


Shiva went everywhere and asked for food but the skull was never full. He finally came here and Maa Annapoorna filled the skull with grains and reversed Shiva’s curse.

It is believed that who ever visits Devi Annapoorna here will never be without food in their lives.
ALL