11za

Command: $ cat rearrange1.py Code output: #!/usr/bin/env python3

import re

def rearrange_name(name):

    result = re.search(r"^([\w .]*), ([\w .]*)$", name)

    if result == None:

        return name

    return "{} {}".format(result[2], result[1]) Command: $ cat rearrange2.py Code output: #!/usr/bin/env python3

import re

def rearrange_name(name):

    result = re.search(r"^([\w .-]*), ([\w .-]*)$", name)

    if result == None:

        return name


    return "{} {}".format(result[2], result[1]) Command: $ diff rearrange1.py rearrange2.py Code output: 6c6

<     result = re.search(r"^([\w .]*), ([\w .]*)$", name)

---

>     result = re.search(r"^([\w .-]*), ([\w .-]*)$", name) Command: $ diff validations1.py validations2.py Code output: 5c5,6

<	assert (type(username) == str), "username must be a string"

--

>	if type(username) != str: 

> 	    raise TypeError("username must be a string")

11a13,15

>	    return False

>	# Usernames can't begin with a number

>	if username[0].isnumeric(): Command: $ diff -u validations1.py validations2.py Code output: --- validations1.py	2019-06-06 14:28:49.639209499 +0200

+++ validations2.py	2019-06-06 14:30:48.019360890 +0200

@@ -2,7 +2,8 @@

 

 

 def validate_user(username, minlen):

-    assert type(username) == str, "username must be a string"

+    if type(username) != str:

+        raise TypeError("username must be a string")

     if minlen < 1:

         raise ValueError("minlen must be at least 1")

     

@@ -10,5 +11,8 @@

         return False

     if not username.isalnum():

         return False

+    # Usernames can't begin with a number

+    if username[0].isnumeric():

+        return False

     return True

Git Guide 0: How to Diff Files

Building a (simple) Blog with Rust

Scientific American Supplement, No. 711, August 17, 1889, by Various, is part of the HackerNoon Books Series. You can jump to any chapter in this book . ELECTRIC LIGHTING AT THE PARIS EXHIBITION—THE OERLIKON WORKS. here ELECTRIC LIGHTING AT THE PARIS EXHIBITION—THE OERLIKON WORKS. Immediately on entering the Machinery Hall by the leading from the central dome, and occupying a prominent position at the commencement of the Swiss section, is a very important plant of dynamos, motors, and steam engines, put down by the Oerlikon Works, of Zurich. During the time the machinery is kept running in the hall, power is supplied electrically to drive the whole of the main shafting in the Swiss section and part of that in the Belgian section, amounting in all to some 200 ft., a large number of machines of various industries deriving their power from these lines of shafting, while during the evening a portion of the upper and lower galleries adjoining this section is lit by some twenty-five arc lamps run from this exhibit. Steam is supplied from the Roser boilers in the motive power court. The whole of the generating plant is illustrated in one view, and a separate view is given of the motor employed to drive the main shafting, this latter view showing the details of connection to the same. On the extreme right hand side of the first view is a direct coupled engine and dynamo of 20 horse power, a separate cut of which is given in Fig. 3. The engine is of the vertical single cylinder type, standing 5 ft. high, and fitted, as are the other two engines exhibited, with centrifugal governor gear on the fly wheel, acting directly on the throw of the cutoff valve eccentric. The two standards, supporting the cylinder and forming the guide bars, together with the entire field magnets and pole pieces of the dynamo, and the bed plate common to both, are cast in one piece. galerie The winding is compound, and in such a direction that the two opposite horizontal poles have the same polarity; it follows from this that there will be two consequent poles in the iron, these being opposite in name to the horizontal poles and at right angles to them, viz., above and below the armature. Opposite sections of the commutator are connected together internally as in most four-pole machines, so that only two brushes are necessary, at 90 deg. apart. The section of iron in the field is 60 square inches and rectangular in form, and the whole machine measures 4 ft. 3 in. in length, and 2 ft. in height, without including the height of the bed plate. The armature is 17 in. in length and the same in diameter, measured over the winding, and develops at the machine terminals 70 volts and 200 amperes at 480 revolutions. The moving parts of the engine are well balanced, and run remarkably well and without noise at this high rate of speed. This dynamo serves to develop power to run a motor in an adjoining inclosure, containing some fine specimens of lathes and machine tools constructed by the Oerlikon Works. These are driven by the motor through the medium of a countershaft, and the power and speed are controlled from the switch board seen at the left of the exhibit, and in Fig. 11. The resistance, R1, serves to vary the intensity of the shunt field of the dynamo, the volts being indicated by the voltmeter V1, and a resistance separate from the switch board is inserted in the main circuit of the two machines. The ammeter, A2, is directly connected to the dynamo, and therefore indicates the current, whatever circuit this machine is running. A larger combined engine and dynamo, seen in the center of the stand, serves to run the lighting of the galleries. The engine is a 60 horse power compound, running at 350 revolutions, and fitted with a governor on the fly wheel, like that described above. The dynamo is a two-pole machine, the upper pole and yoke being cast in one, and the lower pole, yoke, and combined bed plate forming a separate casting. The two vertical cores, over which the field bobbins are slipped, are of wrought iron, and are turned with a shoulder at either end, the yokes being recessed to fit them exactly. The cores are then bolted to the yokes vertically from the top and horizontally below. The field of this machine is shunt-wound, and in order to maintain the potential constant a hand-regulated resistance—R2 on the switch board—is added in circuit with the shunt field. The voltmeter, V2, immediately above this resistance, serves to indicate the difference of potential at the machine terminals. Both voltmeters are fitted with keys, so that they are only put in circuit when the readings are taken. The main terminals of this machine are fitted on substantial insulating bases, fixed one at each end of the top yoke. These connect to the external circuit by a heavy cable—the machine being capable of developing 500 amperes—and to the shunt circuit, and regulating resistance by small wires; while the two connections to the brushes are by four covered wires in parallel on each side. This mode of connection is more flexible than a short length of heavy cable, and looks well, the wires being held neatly together by vulcanized fiber bridges. The dynamo is a low tension machine, the field being regulated to give 65 volts when running the lamp circuits. The illustration, Fig. 10, represents the automatic re-regulator—C.E.L. Brown's patent. Motion is imparted to the cores of two electro-magnets at the ends by the pulleys, W W1. The cores have a projection opposite to the spindle, , which latter is screw-threaded. By a relay one or other electro-magnet is put in action, and the rotating core, which is magnetized, causes rotation of the spindle by attraction, resulting in the movement of the contact along the resistance stops. The relay is acted upon directly by the potential of the dynamo, and the variable resistance is included in the shunt field of the machine, so that changes in the potential, resulting from changes in load or speed, are compensated for. a b The arrangements of the lamp circuits and the lamp itself may now be described. The lamps are all run in parallel circuit, but are divided into groups of five, each group being controlled by a separate switch on the board—Figs. 11 and 11a. These switches are not in direct communication with the dynamo, but make that connection through a large central switch, S2, which therefore carries the whole current. The returns from each group are brought to the connections seen between the two resistances, where the circuits may be disconnected if desired, and the main current then passes through the ammeter, A3, to the other terminal of the machine. One of the smaller switches at the top, Fig. 11a, is directly connected with one terminal of the 20 horse power dynamo before mentioned, and the other side of the switch to the motor in the machine tool exhibit. Also one of the switches in connection with the central switch, S2, is connected to the same motor, and therefore the latter may be run by either machine, or, in fact, any combination of machines, lamps, and motor be made as required. The form of switch made by the Oerlikon Works is illustrated in Fig. 7. Two thick semicircular bands of copper are screwed at one end to opposite sides of a square block which is turned round by the switch handle. The block has a projection at each corner, and two strong, flat, stationary springs are attached to the framework of the switch and press on opposite sides of the block. The ends of the springs engage in the projections and prevent the switch being turned round the wrong way, while the pressure of the springs on opposite sides forces the copper bands to take up a position exactly in line with the terminal contacts when the switch is closed, or at right angles to them when it is opened. Further, each lamp has its own separate adjustable resistance, fuse, and switch. These are of special construction, combined in one, and are illustrated in Figs. 4 and 4a; the other figures, 4b and 4c, showing some of the details of the same. The wires, W W, lead from and to one lamp. The current enters at one wire, passes through the fuse, —Figs. 4c and 4a—down the center of the cylinder to a divided contact, into which a switch arm can be shot. When this is so, a connection is made to the upright brass rod, T, which serves to grip the band, R, passing round the body of the cylinder. The current then passes through all the turns of wire above the band, and out at the other terminal. The resistance can be varied by raising or lowering the band. Fig. 4b shows the manner of tightening the band against the wires on the cylinder. The upright rod, T, is seen in section, and is fixed in one position to the frame of the apparatus. Abutting against this, and working in the block to which the two ends of the band are screwed, is a thumb screw, S, by turning which the band may be loosened for adjusting, and tightened when the right position is found. The cylinder is covered with asbestos sheet, and the wire, which is of nickel, and measures altogether from 3 to 4 ohms, is wound helically round this. The switch arm, to which the handle is attached below, does not itself make and break the circuit, but carries a spring, as shown, which, when the arm is at the end of its movement, pulls over the contact lever with a rapid action, shooting the same between the divided contact piece, and making a perfect contact. The switchboard forms one side of a closed wooden case or cupboard, with sufficient room for a man to enter and adjust the resistances or switches for each lamp. These are screwed to the inside of the case in rows, to the number of twenty-five. The greatest care has been taken in the fixing of the connections to the inside of this case, and no leading wires of different potential are allowed to cross each other. f The Oerlikon lamp, which is designed to work with constant potential, is shown partly in section in Fig. 8. There is only one solenoid, A, through which all the current passes, and whose action is to strike the arc and maintain the current constant. The soft iron core, C, is suspended from the inside of the tube, T, in which it has an up and down movement checked by an air piston in the tube. An end elevation of the brake wheels and solenoid is given in Fig. 9, where it will be seen that the spindle carrying these wheels also carries between them a pinion engaging with the rack rod, R. The top carbon attached to the rack rod falls by its own weight, and is therefore in contact with the lower carbon before the lamp is switched in circuit. When this is done the core is instantly magnetized, and attracted to the soft iron brake wheels, which it holds firmly. The air cushion in the tube prevents the core being drawn up until it has fairly gripped the sides of the wheels. The subsequent raising of the core therefore turns the wheels, raises the rack rod, and strikes the arc. The feed is operated by the weakening of the magnetic field of the coil, which causes the core to lose its grip of the wheels, and allows the top carbon to descend. The catch, L, Fig. 8, has a lateral play, and serves to engage in the teeth of the rack rod, so as to prevent its falling when being trimmed. Each carbon when in position is held against two rectangular guide bars by the pressure of a wire spring—see figure. In this way the carbon is pressed against two parallel knife edges, and is therefore always in true alignment. The action of the lamp is very simple, the working parts are few and solidly constructed, and the regulation, as exhibited by the lamps running in the galleries, is exceptionally steady. The transmission of power plant consists of two 250 horse power dynamos—C.E.L. Brown's patent—the generator being driven by a vertical compound condensing engine of the same power, running at 180 revolutions. The dynamo generator is a four-pole 600 volt direct current machine, series wound, and may be distinguished in the engraving next to the switch board; while the motor receiver connected to it, and erected in another portion of the Swiss section, is of exactly the same size and type. The field, which is hexagonal in shape, is cast in two pieces, bolted together horizontally, the cross-sectional area of iron being 170 square inches. The armature is cylindrical, and built up of flat rings stamped out of soft sheet iron, eight notches in the same being provided to fit over the arms of the spider keyed to the shaft. The spider is in halves, which are bolted together longitudinally after the rings are in position. It is Gramme wound, and measures over the winding 7 in. radial depth, 37 in. outside diameter, and 22 in. in length. The current is collected by four brushes. The fitting and mechanical build of the dynamos leaves nothing to be desired. All the working parts of the dynamos and engines are turned up to gauge and template, so as to be interchangeable. As an instance of this, the armature of the generator was built in the works, while the field magnets were being erected in the exhibition, and, on arrival, fitted in position perfectly, and ran at once without trouble. The energy taken off on the motor shaft is close on 200 horse power, but varies according to the machines at work; the speed of the motor does not, however, vary more than 3 per cent., and the brushes need no adjustment. About 6 ft. of shafting is coupled on in line with the motor shaft, and an extra plummer block fixed at the end. This shafting carries at its extremity an additional 2 ft. pulley, the power being delivered by belting from these pulleys to two large pulleys on the main shaft. The machines run by this transmission consist of the looms of Rieter & Co., of Winterthur; the large flour mill and lift of A. Millot & Co.; the flour milling machinery of Frederick Wegmann & Co., of Zurich; the brick and tile making machines of the Rorschach foundries; and the looms of Messrs. Houget & Teston, of Verviers, in the Belgian section. A 15 horse power two-pole Oerlikon dynamo is also run by a belt from the main shaft, and generates power to drive a motor of similar type in the Swiss section of the upper gallery. This runs a length of countershafting supplying power to three silk-weaving machines constructed by Benninger Frères; six weaving machines from the Ruti works, near Zurich; and one knitting machine exhibited by Edward Dubied & Co., of Couvet. The dynamo and motor are connected to the main cable by switches of the type shown in Fig. 5. These are specially designed to destroy the extra current on breaking circuit by the formation of an arc which gradually increases the resistance till the break occurs, rendering it less sudden. One wire passes through the handle and makes contact with the springs, and the other is attached to the clamp in which the carbon rod is held. The current is made to enter at the carbon rod, so that the arcs formed cause consumption of the carbon. A magnetic cut-out—Fig. 6—is also provided to each machine; this consists of an electro-magnet, through which the main current passes, provided with side pole pieces. A flat soft iron plate armature is hinged so as to come up against the pole pieces when attracted. When the current is not sufficiently strong to cause the plate to be attracted, a hole in the center of the latter engages over a small projection in the top of a weighted arm hinged in the center of the board, and keeps it upright. If now the current exceeds the limits of safety to the machine, due to a too heavy load being thrown on, the armature is attracted and releases the vertical arm, which falls over and enters with considerable force between the two spring contacts below. These contacts are connected to the field terminals, which are, therefore, short-circuited, and prevent the dynamo generating any current. A retractile spring can be adjusted to cause cut-off at any required current. These details are indicated in our illustrations mounted on their respective switch boards. Since the erection of plant by these works at Solothurn for transmitting 50 horse power five miles distant, which attracted so much interest some time ago, several important works have been carried out. Among these we may mention a 280 horse power transmission at 1½ kilom. distance to a cotton mill at Derendingen in Switzerland, a 250 horse power transmission at ½ kilom. distance, carried out for Gaetano Rossi at Piovene in Italy, and a 300 horse transmission at 6 kilom. distance installed for Giovanni Rossi, in which the power is given off at two different stations.— The Engineer. About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Various (2004). Scientific American Supplement, No. 711, August 17, 1889. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/16972/pg16972-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at , located at . www.gutenberg.org https://www.gutenberg.org/policy/license.html

ELECTRIC LIGHTING AT THE PARIS EXHIBITION—THE OERLIKON WORKS

THE SONG OF THE MOTH

Feature Image: Zuck announcing Threads’ several first milestones on Threads itself As of 2:15pm Indochina Time on Friday July 7, Threads, the Instagram’s “Twitter-killer” app, has passed 60 Million downloads. I signed up & connected one of my secondary Instagram accounts to it just now to confirm, and that account was user # 60,614,427. In comparison, when I set up t at around 11am ICT Thursday July 6, about 5 hours after it officially launched in Asia, we were user #6,519,297. Our number would have been a bit lower if we were still in the US, the first region to roll out Threads. Zuck, of course, was . That means, in just over 48 hours since launch, the app had passed 60 Million users, officially crowning it the fastest app that reached this milestone. The fastest growing app in recent consciousness that was able to do something even close to it, was , which amassed . the official HackerNoon Threads accoun user #1 ChatGPT 1M users within a week post launch There will be more stories on HackerNoon about Threads soon, but I want to jot down a few thoughts on this high growth app, while it’s still new(ish). Twitter sucks (bad) right now; and people have been desperate for an alternative since Musk’s reign Twitter wasn’t perfect pre Elon Musk, but it wasn’t . The latest straw that broke the camel’s back for many people was Musk’s erratic decision to . Specifically, he rate limits the number of tweets not just for regular users to 600 tweets/day; but also for paid users (who pay Musk $8/month to get a verified checkmark next to their name) to 6000 tweets/day. His rationale was that this rate limit but I think it’s much simpler than that: he needs the money. “Free speech”, but only if you give me $8/month. Among Musk’s many terrible decisions that make Twitter the hellscape it is today, we have: the disaster it is today limit access to all Twitter & non Twitter users alike prevents AI companies from scraping Twitter data; Firing close to 75% of its staff (in multiple waves) in a largely undignified, cold-hearted manner Making the site unstable, largely unmoderated, and buggy, possibly due to the firing of many key staff with institutional knowledge Not paying many employees whom he let go, including In April of this year, they ex CEO Parag Agrawal, ex CLO Vijaya Gadde, and ex CFO Ned Segal. filed a joint lawsuit against him Scaring off enough advertisers due to the (in the name of free speech) that advertising revenue is reportedly unmoderated nature of Twitter 2.0 content down at least 59% Not making enough money on , after the disastrous first launch attempt that generated so many scams and impersonation attempts, . Since , it reportedly made under $50 Million. Together with advertising hovering around $1,8 Billion, . Twitter Blue subscription costing valuable advertisers & brands real money the relaunch Twitter’s YoY revenue post Elon is down 40%, from around $5 Billion pre-Elon Oh yes, . He was forced into it because he made a bad calculation . A “0 % interest rate” phenomenon you might say. . he wasn’t even going to buy the site in the first place overvaluing his Tesla stock $44 Billion USD isn’t cheap, even for the richest man on earth Reading stories about Musk’s handling of Twitter felt alarmingly similar to reading stories about the Trump’s presidency. Scandals after scandals. Bad decisions followed by worse decisions. It was anxiety and fatigue-inducing. So, naturally, people have been looking for a viable alternative ever since Elon Musk took over Twitter. But no platform ( , , , to name a few) was able to achieve mass adoption, until… Mastodon BlueSky Cohost Threads is not run by Elon Musk Look, I get it, a Twitter alternative from Zuck ( with of his own) sounds a little lame. It’s not due to just that, all of Zuck’s fraud history with European regulators. BUT. The bar is so low right now. And love him or hate him, Zuck WHILE AND . Simply put, the bar for people to like a social media app in 2023 is just, “not run by Elon Musk.” That’s why some people rekindled their hope for Twitter after learning that its new CEO will be , who is very respected in the advertising industry. Others go to great length to set up a server for their Mastodon instance (I haven’t). another billionaire multiple baggages even available in the EU right now knows how to run social media firing a lot of his staff not scaring over half of his advertisers Linda Yakarino Lately, Zuck has been entertaining the idea of challenging Musk in (lol). I think that was the first time since Cambridge Analytica that a meaningfully larger number of people might actually root for Zuck instead of Musk. It does take a worse billionaire like Musk to make Zuck look civil and worth rooting for. a cage fight The Metaverse is still a long shot Zuck, too, was fueled by desperation. made it clear that gone are the days of Instagram’s purchase (imho, Zuck’s best acquisition to date). With intesifying regulators’ scrutiny from all sides, it seems that he’s no longer allowed to gain monopoly on social media by simply buying up competitions. . He needed to hedge new bets, considering Facebook growth was severely capped, with no end in sight. The UK’s decision to block Meta’s acquisition of Giphy The UK specifically cited the fact that Meta already controlled over 50% of the advertising market in the UK as the reason to block Giphy acquisition In October 2021, Zuck announced the relaunch of Facebook as Meta (our parody ), . Ever since, he has burned billion of dollars into this pipedream ( , $10 billions in 2022, and planning to be about $100 billions over the next couple of years). here announcing that Facebook Instagram, and Whatsapp, are just products belonging to the parent company Meta reportedly Unfortunately, the Metaverse had not yet to pan out the way he hoped. . People’s avatars look awkward, cartoonish, and limited, nothing like the person they attempted to represent (see some ). The remains quite niched and largely unfriendly to the general public. Unlike the cash counter that is advertising money from Facebook, Instagram and Whatsapp, Zuck’s Metaverse vision seemed to be quite far-off, and not exactly what the people want, or need, right now. At some point, none of the people in there had legs here Oculus Quest To add salt to the wound, earlier this year, Apple announced that it will . Expensive though it seemed, this move by Apple might effectively one-up and undercut Meta’s market share into AR/VR. And of course, the growth of generative AI, most notably with chat GPT, has very little to do with Zuck’s metaverse pipe dream. launch the Apple Vision Pro Threads is shamelessly Twitter-like, and the people running it are the first to admit it If you are one of the that are reportedly active on Instagram in 2023, signing up for threads literally takes 3 seconds, as you can sign in with your existing Instagram handle. Once there, you have the option to import your Instagram bio, profile picture, and link. You also have the option to follow anyone whom you already followed on Instagram, even before they join Threads. That way, once they do join, you would already be one of their followers. A “pre-follow” if you will. 1,4 billions users From there, it’s basically Twitter, without the baggage and all the added features. Adam Moserri, , and multiple public threads on , accredits Twitter for pioneering the “reply format”, which gives the same design treatment for comment as it does for the original post, creating a natural "public conversation”. This is vastly different than commenting on Youtube, Facebook, or Instagram, which gets a “second tiered” design treatment. in an interview his own account The things Threads does have: 500 character limit for each post Ability to retweet (called “repost”), and quote tweet (called “quote”) Ability to comment/reply A like counter, and a reply counter (both can be hidden) Search for users’ handle Way to go back and forth seamlessly between Threads and Instagram. My favorite is the “add to story” button that shares Tweet in a beautiful pre-designed manner As mentioned above, ability to bring most of your Instagram followers with you And of course, a lot of users already, since it’s basically Instagram but “not Twitter” Twitter The things it doesn’t have (I shared these in my first threads ): here A personalized or even just chronological newsfeed that surface only the people you follow An inbox (post all on main, i guess, lol) Ability to switch between multiple accounts Ability to search for anything else that’s not a handle Elon Musk =)) The weird quirks: Threads algorithm seems very random and buggy right now. I was reading an interesting thread, and the feed just refreshes itself. Since I cannot search and don’t remember the handle, that content is now gone forever from my feed. Annoying buzzing and endless notifications as default for some users Owned by . Meta In general, I don’t think it’s perfect, but I already like and use it way more than Twitter. And I assume a non-trivial percentage of Instagram avid userbase will feel the same. Threads might save Zuck. But it’s too early to tell. (or, in Musk’s word, “ ”). We’ll see how the case go. But at first glance, this is one of the clearest signs of Musk feeling threatened by this app in a real way that he never did with Mastodon or BlueSky (cofounded by Jack Dorsey, who remains a Twitter/X Corp ). Twitter Lawyer Alex Spiro already threatened to sue Zuck over stealing its “trade secrets” cheating is not okay shareholder But the true test will be users’ retention, and eventually monetization. In both Zuck’s and Monserri’s public statements, they emphasized the word “friendly”, implying their strong focus & commitment on content moderation. They also claimed that the platform is “decentralized,” as it will implement a protocol called ActivityPub. This means, users of Mastodon could potentially migrate back & forth between the two platforms, as well as users of any other platform that implements ActivityPub. It definitely is a smart move for optic. But given the history of Facebook/Meta’s handling of users’s data, I don’t think it will win over enough users for whom decentralization and privacy are their top concerns. The app will probably pass 100M users any day now. But a large percentage of the userbase will probably leave after the initial honeymoon period. What they do then, how careful they are with users data & integration (under extreme scrutiny from both regulators and reporters), what features they will add or kill, and most importantly, what users will they be able to convert to long term users, will determine the future of this app, and by extension, the legacy of Zuck. For now, I know that I have nothing to lose by posting on Threads directly to my Instagram stories, as I’m already too addicted to Instagram.

Threads might be Zuck's smartest business move since Instagram

থ্রেডগুলি ইনস্টাগ্রামের পর থেকে জুকের সবচেয়ে স্মার্ট ব্যবসায়িক পদক্ষেপ হতে পারে

Threads könnten Zucks intelligentester Geschäftsschritt seit Instagram sein

Threads podría ser el movimiento comercial más inteligente de Zuck desde Instagram

Les discussions pourraient être la décision commerciale la plus intelligente de Zuck depuis Instagram

इंस्टाग्राम के बाद थ्रेड्स ज़ुक का सबसे स्मार्ट बिजनेस कदम हो सकता है

スレッドは、インスタグラム以来のザックの最も賢明なビジネスの動きかもしれない

스레드는 Instagram 이후 Zuck의 가장 현명한 비즈니스 움직임일 수 있습니다.

Tópicos podem ser a jogada de negócios mais inteligente de Zuck desde o Instagram

Threads, Zuck'ın Instagram'dan bu yana yaptığı en akıllı iş hamlesi olabilir

Chủ đề có thể là động thái kinh doanh thông minh nhất của Zuck kể từ Instagram

Threads 可能是扎克自 Instagram 以来最明智的商业举措

Architectural Designs

The Earth's Beginning by Robert S. Ball is part of the HackerNoon Books Series. You can jump to any chapter in this book here . THE HISTORY OF THE SUN CHAPTER VII. THE HISTORY OF THE SUN The Inconstant Sun—Representation of the Solar System at different Epochs—Primæval Density of the Sun—Illustration of Gas in Extreme Tenuity—Physical State of the Sun at that Period—The Sun was then a Nebula. We pointed out in the last chapter how, in consequence of its perennial loss of heat, the orb of day must be undergoing a gradual diminution in size. In the present chapter we are to set down the remarkable conclusions with respect to the early history of the sun to which we have been conducted by pursuing to its legitimate consequences the shrinkage which the sun had undergone in times past. The outer circle in Fig. represents the track in which our earth now revolves around the sun, and we are to understand that the radius of this circle is about ninety-three million miles. We must imagine that the innermost of the four circles represents the position of the sun. Along its track the earth revolves year after year; so it has revolved for centuries, so it has revolved since the days of the first monarch that ever held sway in Britain, so it has revolved during all the time over which history extends, so it has doubtless revolved for illimitable periods anterior to history. For an interval of time that no one presumes to define with any accuracy the earth has revolved in the same track round that sun in heaven which, during all those ages, has dispensed its benefits of light and heat for the sustenance of life on our globe. 19 Fig. 19.—To Illustrate the History of the Sun. Present orbit of Earth. Sun in times very much earlier still. Sun in very early times. Present Sun. The sun appears constant during those few years in which man is allowed to strut his little hour. The size of the sun and the lustre of the sun has not appreciably altered. But the sun does not always remain the same. It has not always shone with the brightness and vigour with which it shines now; it will not continue for ever to dispense its benefits with the same liberality that it does at present. The sun is always in a state of change. It 114would not indeed be correct to refer to these changes as growths, in the same sense in which we speak of the growth in a tree. Decade after decade the tree waxes greater; but the sun, as we have already explained, does not increase with the time, for the change indeed lies the other way. It may well be that in this present era the sun is near its prime, in so far as its capacity to radiate warmth and brightness is concerned. It is, however, certain that the sun is not now so large as it was in ancient days. The diminution of the orb is still in progress. In these present days of its glorious splendour the orb of day is much larger than it will be in that gloomy old age which destiny assigns to it. We have already shown how to give numerical precision to our facts. We have stated that the sun’s diameter is diminishing at the rate of one mile every eleven years. We have dwelt upon the remarkable significance of that shrinkage in accounting for the sustentation of the sun’s heat. We have now to call on this perennial diminution of the sun’s diameter to provide some information as to the early history of our luminary. The innermost circle in our sketch is to suggest the sun as it is at present. Millions of years ago the orb of day was as large as I have indicated it by the circle with the words “sun in very early times.” It will, of course, be understood that we do not make any claim to precise representation of the magnitude of the orb. At a period much earlier still, the sun must have been larger still, and we venture so to depict it. We know the rate at which the sun is now contracting, and doubtless this rate has continued sensibly unaltered during thousands of years, and indeed we might say scores of thousands of years. But it would not be at all safe to 115assume that the annual rate of change in the sun’s radius has remained the same throughout excessively remote periods in its evolutionary history. What we do affirm is, that in the course of its evolution the sun must have been contracting continually, and we have been able to learn the particular rate of contraction characteristic of the present time. But though we are ignorant of the rate of contraction at very early epochs, yet the sun ever looms larger and larger in days earlier and still earlier. But in those early days the sun was not heavier, was not, indeed, quite so heavy as it is at present. For we remember that the sun is perennially adding thousands of tons to its bulk by the influx of meteors. Perhaps we ought to add that the gain of mass from the meteors may be to some extent compensated by the loss of substance which the sun not infrequently experiences if, as is sometimes supposed, it expels in some violent convulsion a mass of material which takes the form of a comet (Fig. ). 21 Let us now consider what the density of the sun must have been in those primæval days, say, for example, when the luminary had ten times the volume that it has at present. Even now, as already stated, it does not weigh half as much again as a globe of water of the same size, so that when it was ten times as big its density must have been only a small fraction of that of water. But we may take a stage still earlier. Let us think of a time—it was, perhaps, many scores of millions of years ago—when the sun was a thousand times as big as it is at present. The same quantity of matter which now constitutes the sun was then expanded over a volume a thousand times greater. A remarkable conclusion follows from this consideration. The air that we breathe has a density which is about the seven-hundredth 116part of that of water. Hence we see that at the time when the materials of the sun were expanded into a volume a thousand times as great as it is at present the density of the luminary must have been about equal to that of ordinary air. We refer, of course, in such statements to the average density of the sun. It will be remembered that the density of the sun cannot be uniform. The mutual attractions and pressures of the particles in the interior must make the density greater the nearer we approach to the centre. We must push our argument further still. We have ascertained that the primæval sun could not have been a dense solid body like a ball of metal. It must have been more nearly represented by a ball of gas. There was a time when that collection of matter which now constitutes the sun was so big that a balloon of equal size, filled at ordinary pressure with the lightest of known gases, would contain within it a heavier weight than the sun. At this early period the sun must have been as light as an equal volume of hydrogen. The reasoning which has conducted us to this point remains still unimpaired. From that early period we may therefore look back to periods earlier still. We see that the sun must have been ever larger and larger, for the same quantity of material must have been ever more and more diffused. There was a time when the mean density of the sun must have been far less than that of the gas in any balloon. We must not pause to consider intermediate stages. We shall look back at once to an excessively early period when the sun—or perhaps we ought rather to say the matter which in a more 117condensed form now constitutes the sun—was expanded throughout the volume of a globe whose radius was as great as the present distance from the sun to the earth. Have we not here truly an astonishing result, deduced as a necessary consequence from the fundamental laws of heat? Fig. 20.—The Solar Corona (January 1st, 1899). (Photographed during Eclipse by Professor W. H. Pickering.) I need hardly say that the sun at that early date did not at all resemble the glorious orb to which we owe our very existence. The primæval sun must have been a totally different object, as we can easily imagine if we try to think that the sun’s materials then filled a volume twelve million times as great as they occupy at present. Instead of comparing such an object with the gases in our ordinary atmosphere, it should rather be likened to the residue left in an exhausted receiver after the resources of chemistry have been taxed to make as near an approach as possible to a perfect vacuum. We can give a familiar illustration of gas in a state of extreme tenuity. Look at the beautiful incandescent light with which in these days our buildings are illuminated. How brilliantly those little globes shine! The globe has to be most carefully sealed against the outside air. If there were the smallest opportunity for access, the air from outside would rush in and the lamp would be destroyed. In the preparation of such a lamp elaborate precautions have to be taken to secure that the exhaustion of the air from the little globe shall be as nearly perfect as possible. Of course it is impossible to remove all the air. No known processes can produce a perfect vacuum. Some traces of gas would remain after the air-pump had been applied even for hours. We must now imagine a globe, not merely two inches in diameter like one of these little lamps, but a globe 186,000,000 miles in diameter, a globe so large that the earth’s orbit would just form a girdle round it. Even if this globe had been exhausted, so that its density was only the twelve-thousandth part of the ordinary atmospheric density, it would still contain more material than is found in the sun in heaven. Thus our reasoning has conducted us to the notion of an epoch when the sun—or rather I should say the matter composing the sun—formed something totally different from the orb which we know so well. The matter in that very diffuse state would not dispense light and heat as a sun in the sense in which we understand the word. However vast might be the store of energy which it contained—a store indeed thousands of times greater than our present sun possesses—yet it would hardly be possessed of the power of effective radiation. It would assuredly not be able to warm and light a world associated with it, in the same way as the sun now provides so gloriously for our wants and comfort. Fig. 21.—The Great Comet of 1882. (Photographed on November 7th, 1882, by Sir David Gill, K.C.B.) But it is certain that in those early days there was no earth to be warmed and lighted. Our globe, even if it can be said to have existed at all, was truly “without form and void.” At the time when the sun was swollen into a great globe of gas or rarefied matter, the elementary substances which were to form the future earth were in a condition utterly different from that of our present globe. The history of this earth itself involves another chapter of the argument. Let it suffice to notice, for the present, that our reasoning has led us to a time when the sun consisted only of a rarefied gaseous material, and let us give to the matter in this condition the name which astronomers apply to any object of a similar character wherever they may meet with it in the universe. Suppose that we could observe through our telescopes at the present moment an object in remote space which was like what the sun must have been at that early stage of its existence which we have been considering, I do not think that the object would be unfamiliar to astronomers. There is, indeed, no doubt that there are many objects visible at this moment, and nightly studied in our observatories, which are formed of matter just in the same state as the sun was in those early times. Examined with a good telescope, the object would seem like a small stain of light on the black background of the sky. The observer would at once call it a nebula. In these modern days he would probably apply the spectroscope to it, and this instrument would assure him that the object he was looking at was a mass of incandescent gas. Such an object would in all probability not greatly differ from many nebulæ now known to us. This being so, why should we withhold from the sun of primitive days the designation to which it seems to be so fully entitled? Why should we not speak of it as a nebula? The application of the laws of heat has shown that the great orb of day was once one of those numerous objects which astronomers know as nebulæ, and perhaps it may not be too fanciful to suppose that a trace of the primæval nebula still survives in what we call the Solar Corona (Fig. ). 20 About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Robert S. Ball (2019). The Earth's Beginning. Urbana, Illinois: Project Gutenberg. Retrieved October 2022 https://www.gutenberg.org/cache/epub/59080/pg59080-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org , located at https://www.gutenberg.org/policy/license.html .

THE HISTORY OF THE SUN

FIRST QUARTER TO FULL MOON

11ZA

11za.com

-- employees

Since n.d.

COMPANY RANKING

11ZA

EVERGREEN INDEX #1547

Representing this company? Click here to claim and customize this page!

11za WIKI

Apply to get your Tech Company News Page live on HackerNoon.com today!

11ZA

11za.com

-- employees

Since n.d.

COMPANY RANKING

11ZA

EVERGREEN INDEX #1547

RELATED COMPANIESRANK

STORIES ABOUT 11ZA

Representing this company? Click here to claim and customize this page!

11za WIKI

Apply to get your Tech Company News Page live on HackerNoon.com today!