Egyptians, made little distinction between shape and number. Even today, when we square a number (x²), this is equivalent to converting a line into a square and calculating its area. Pytha*****ans were mystified by this connection between shapes and numbers, which explains why they didn’t conceive of zero as a number: after all, what shape could represent nothingness? Ancient Greeks believed numbers had to be visible to be real, whereas the ancient Indians perceived numbers as an intrinsic part of a latent, invisible reality separate from mankind’s conception of them.
The symbol of the Pytha*****an cult was the pentagram (a five-pointed star); this sacred shape contained within it the key to their view of the universe—the golden ratio. Considered to be the “most beautiful number,” the golden ratio is achieved by dividing a line such that the ratio of the small part to the large part is the same as the ratio of the large part to the whole. Such proportionality was found to be not only aesthetically pleasing, but also naturally occurring in a variety of forms including nautilus shells, pineapples, and (centuries later) the double-helix of DNA. Beauty this objectively pure was considered to be a window into the transcendent; a soul-sustaining quality. The golden ratio became widely used in art, music, and architecture
The golden ratio was also found in musical harmonics: when plucking a string instrument from its specified segments, musicians could create the perfect fifth, a dual resonance of notes said to be the most evocative musical relationship. Discordant tritones, on the other hand, were derided as the “devil in music.” Such harmony of music was considered to be one and the same with that of mathematics and the universe—in the Pytha*****an finite view of the cosmos (later called the Aristotelean celestial spheres model), movements of planets and other heavenly bodies generated a symphonic “harmony of the spheres”—a celestial music that suffused the cosmic depths. From the perspective of Pytha*****ans, “all was number,” meaning ratios ruled the universe. The golden ratio’s seemingly supernatural connection to aesthetics, life, and the universe became a central tenet of Western Civilization and, later, The Catholic Church (aka The Church).
Zero posed a major threat to the conception of a finite universe. Dividing by zero is devastating to the framework of logic, and thus threatened the perfect order and integrity of a Pytha*****an worldview. This was a serious problem for The Church which, after the fall of the Roman Empire, appeared as the dominant institution in Europe. To substantiate its dominion in the world, The Church proffered itself as the gatekeeper to heaven. Anyone who crossed The Church in any way could find themselves eternally barred from the holy gates. The Church’s claim to absolute sovereignty was critically dependent on the Pytha*****an model, as the dominant institution over Earth—which was in their view the center of the universe—necessarily held dominion in God’s universe. Standing as a symbol for both the void and the infinite, zero was heretical to The Church. Centuries later, a similar dynamic would unfold in the discovery of absolute scarcity for money, which is dissident to the dominion of The Fed—the false church of modernity.
Ancient Greeks clung tightly to a worldview that did not tolerate zero or the infinite: rejection of these crucial concepts proved to be their biggest failure, as it prevented the discovery of calculus—the mathematical machinery on which much of the physical sciences and, thus, the modern world are constructed. Core to their (flawed) belief system was the concept of the “indivisible atom,” the elementary particle which could not be subdivided ad infinitum. In their minds, there was no way beyond the micro barrier of the atomic surface. In the same vein, they considered the universe a “macrocosmic atom” that was strictly bound by an outermost sphere of stars winking down towards the cosmic core—Earth. As above, so below: with nothing conceived to be above this stellar sphere and nothing below the atomic surface, there was no infinity and no void
Aristotle (with later refinements by Ptolemy) would interpret this finite universe philosophically and, in doing so, form the ideological foundation for God’s existence and The Church’s power on Earth. In the Aristotelean conception of the universe, the force moving the stars, which drove the motion of all elements below, was the prime mover: God. This cascade of cosmic force from on high downward into the movements of mankind was considered the officially accepted interpretation of divine will. As Christianity swept through the West, The Church relied upon the explanatory power of this Aristotelean philosophy as proof of God’s existence in their proselytizing efforts. Objecting to the Aristotelean doctrine was soon considered an objection to the existence of God and the power of The Church.
Infinity was unavoidably actualized by the same Aristotelean logic which sought to deny it. By the 13th century, some bishops began calling assemblies to question the Aristotelean doctrines that went against the omnipotence of God: for example, the notion that “God can not move the heavens in a straight line, because that would leave behind a vacuum.” If the heavens moved linearly, then what was left in their wake? Through what substance were they moving? This implied either the existence of the void (the vacuum), or that God was not truly omnipotent as he could not move the heavens. Suddenly, Aristotelean philosophy started to break under its own weight, thereby eroding the premise of The Church’s power. Although The Church would cling to Aristotle’s views for a few more centuries—it fought heresy by forbidding certain books and burning certain Protestants alive—zero marked the beginning of the end for this domineering and oppressive institution.
An infinite universe meant there were, at least, a vast multitude of planets, many of which likely had their own populations and churches. Earth was no longer the center of the universe, so why should The Church have universal dominion? In a grand ideological shift that foreshadowed the invention of Bitcoin centuries later, zero became the idea that broke The Church’s grip on humanity, just as absolute scarcity of money is breaking The Fed’s stranglehold on the world today. In an echo of history, us moderns can once again hear the discovery of nothing beginning to change everything.
Zero was the smooth stone slung into the face of Goliath, a death-stroke to the dominion of The Church; felled by an unstoppable idea, this oppressive institution’s fall from grace would make way for the rise of the nation-state—the dominant institutional model in modernity.
Zero: An Ideological Juggernaut
Indoctrinated in The Church’s dogma, Christianity initially refused to accept zero, as it was linked to a primal fear of the void. Zero’s inexorable connection to nothingness and chaos made it a fearsome concept in the eyes of most Christians at the time. But zero’s capacity to support honest weights and measures, a core Biblical concept, would prove more important than the countermeasures of The Church (and the invention of zero would later lead to the invention of the most infallible of weights and measures, the most honest money in history—Bitcoin). In a world being built on trade, merchants needed zero for its superior arithmetic utility. As Pierre-Simon Laplace said:
“…[zero is] a profound and important idea which appears so simple to us now that we ignore its true merit. But its very simplicity and the great ease which it lent to all computations put our arithmetic in the first rank of useful inventions.”
In the 13th century, academics like the renowned Italian mathematician Fibonacci began championing zero in their work, helping the Hindu-Arabic system gain credibility in Europe. As trade began to flourish and generate unprecedented levels of wealth in the world, math moved from purely practical applications to ever more abstracted functions. As Alfred North Whitehead said:
“The point about zero is that we do not need to use it in the operations of daily life. No one goes out to buy zero fish. It is in a way the most civilized of all the cardinals, and its use is only forced on us by the needs of cultivated modes of thought.”
As our thinking became more sophisticated, so too did our demands on math. Tools like the abacus relied upon a set of sliding stones to help us keep track of amounts and perform calculation. An abacus was like an ancient calculator, and as the use of zero became popularized in Europe, competitions were held between users of the abacus (the abacists) and of the newly arrived Hindu-Arabic numeral system (the algorists) to see who could solve complex calculations faster. With training, algorists could readily outpace abacists in computation. Contests like these led to the demise of the abacus as a useful tool, however it still left a lasting mark on our language: the words calculate, calculus, and calcium are all derived from the Latin word for pebble—calculus.
Before the Hindu-Arabic numerals, money counters had to use the abacus or a counting board to keep track of value flows. Germans called the counting board a Rechenbank, which is why moneylenders came to be known as banks. Not only did banks use counting boards, but they also used tally sticks to keep track of lending activities: the monetary value of a loan was written on the side of a stick, and it was split into two pieces, with the lender keeping the larger piece, known as the stock—which is where we get the term stockholder
Despite its superior utility for business, governments despised zero. In 1299, Florence banned the Hindu-Arabic numeral system. As with many profound innovations, zero faced vehement resistance from entrenched power structures that were threatened by its existence. Carrying on lawlessly, Italian merchants continued to use the zero-based numeral system, and even began using it to transmit encrypted messages. Zero was essential to these early encryption systems—which is why the word cipher, which originally meant zero, came to mean “secret code.” The criticality of zero to ancient encryption systems is yet another aspect of its contribution to Bitcoin’s ancestral heritage.
At the beginning of the Renaissance, the threat zero would soon pose to the power of The Church was not obvious. By then, zero had been adapted as an artistic tool to create the vanishing point: an acute place of infinite nothingness used in many paintings that sparked the great Renaissance in the visual arts. Drawings and paintings prior to the vanishing point appear flat and lifeless: their imagery was mostly two-dimensional and unrealistic. Even the best artists couldn’t capture realism without the use of zero
With the concept of zero, artists could create a zero-dimension point in their work that was “infinitely far” from the viewer, and into which all objects in the painting visually collapsed. As objects appear to recede from the viewer into the distance, they become ever-more compressed into the “dimensionlessness” of the vanishing point, before finally disappearing. Just as it does today, art had a strong influence on people’s perceptions. Eventually, Nicholas of Cusa, a cardinal of The Church declared, “Terra non est centra mundi,” which meant “the Earth is not the center of the universe.” This declaration would later lead to Copernicus proving heliocentrism—the spark that ignited The Reformation and, later, the Age of Enlightenment
A dangerous, heretical, and revolutionary idea had been planted by zero and its visual incarnation, the vanishing point. At this point of infinite distance, the concept of zero was captured visually, and space was made infinite—as Seife describes it:
“It was no coincidence that zero and infinity are linked in the vanishing point. Just as multiplying by zero causes the number line to collapse into a point, the vanishing point has caused most of the universe to sit in a tiny dot. This is a singularity, a concept that became very important later in the history of science—but at this early stage, mathematicians knew little more than the artists about the properties of zero.”
The purpose of the artist is to the mythologize the present: this is evident in much of the consumerist “trash art” produced in our current fiat-currency-fueled world. Renaissance artists (who were often also mathematicians, true Renaissance men) worked assiduously in line with this purpose as the vanishing point became an increasingly popular element of art in lockstep with zero’s proliferation across the world. Indeed, art accelerated the propulsion of zero across the mindscape of mankind.
bitcoin wm ethereum erc20 word bitcoin dapps ethereum bitcoin dynamics exchanges bitcoin обменять ethereum bitcoin hd bitcoin падение bitcoin dogecoin bitcoin poloniex
invest bitcoin
лотерея bitcoin трейдинг bitcoin bitcoin trend bitcoin obmen ethereum кошелька ethereum network flappy bitcoin agario bitcoin падение bitcoin advcash bitcoin bitcoin eu bitcoin protocol bitcoin maps вывод monero bitcoin lion
monero fr nxt cryptocurrency For context, at 90 exahashes per second, the bitcoin network currently consumes approximately 9 gigawatts of power, which translates to -$11 million per day (or -$4 billion per year) of energy at a marginal cost of 5 cents per kWh (rough estimates). Blocks are solved on average every ten minutes, which translates to approximately 144 blocks per day. Across the network, each block costs approximately $75,000 to solve, and the reward per block is approximately $100,000 (12.5 new bitcoin x $8,000 per bitcoin, excluding transaction fees). The higher the cost to solve a block, the more costly the network is to attack. The cost to solve a block represents the tangible resources it requires to write history to the bitcoin transaction ledger. As the network grows, the network becomes more fragmented, and the economic value compensated to miners in aggregate increases. From a game theory perspective, more competition and greater opportunity cost makes it harder to collude, and all network nodes validate the work performed by miners, which serves as a constant check and balance.bitcoin world sec bitcoin pps bitcoin bitcoin пополнить supernova ethereum майнеры bitcoin cubits bitcoin xbt bitcoin exchange ethereum алгоритм monero обсуждение bitcoin bitcoin etf converter bitcoin ethereum видеокарты captcha bitcoin сложность monero
bitcoin algorithm bitcoin favicon bitcoin trojan bitcoin motherboard delphi bitcoin cryptocurrency tech bitcoin список скачать bitcoin buy ethereum аналитика bitcoin bitcoin алгоритмы обучение bitcoin bitcoin hashrate bitcoin download брокеры bitcoin валюты bitcoin
ethereum проблемы bitcoin расчет alliance bitcoin
bitcoin safe книга bitcoin эфириум ethereum iso bitcoin scrypt bitcoin bitcoin презентация monero сложность bitcoin pattern reklama bitcoin nanopool monero Anything can access and use the Bitcoin network and your ethnicity, gender, religion, species, or political leaning are completely irrelevant. This creates vast possibilities for the internet of things. In the future, we could see systems where self-driving taxis or uber vehicles have their own blockchain wallets. The car would be sent cryptocurrency from the passenger and would not move until funds are received. The vehicle would be able to assess when it needs fuel and would use its wallet to facilitate a refill.bitcoin green bitcoin vector bitcoin development android ethereum bitcoin стоимость обои bitcoin tether gps компиляция bitcoin
обменять monero testnet bitcoin
bitcoin betting
ethereum bitcoin падение bitcoin bitcoin instant bitcoin registration lucky bitcoin forbot bitcoin bitcoin это bitcoin calculator
алгоритмы ethereum android tether взлом bitcoin обмен tether bitcoin algorithm lite bitcoin autobot bitcoin bitcoin switzerland пожертвование bitcoin bitcoin 2017 ethereum rub
ethereum кошельки bitcoin plugin bitcoin valet знак bitcoin надежность bitcoin Summarybitcoin софт chain bitcoin ethereum wikipedia bitcoin бонус bitcoin okpay ethereum обменять tether usdt monero fee
bitcoin крах bitcoin 50 bitcoin игры key bitcoin monero xmr контракты ethereum bitcoin сайты get bitcoin love bitcoin кошельки bitcoin курс bitcoin стоимость ethereum bitcoin maining pool bitcoin bitcoin genesis bitcoin dark exchanges bitcoin bitcoin пополнение bitcoin escrow bitcoin блок ethereum linux bitcoin автоматически ethereum прибыльность приложения bitcoin
криптовалюты bitcoin bitcoin symbol In addition to complete privacy, here are some more other unique features of Monero:bitcoin софт bitcoin casino scrypt bitcoin обменять monero bitcoin автоматически ethereum dao bitcoin metatrader bitcoin boxbit bitcoin hardfork tether обменник blogspot bitcoin ethereum график clicks bitcoin bitcoin сигналы monero bitcoin vizit bitcoin биржа рост ethereum bitcoin wmx bitcoin security
habrahabr ethereum addnode bitcoin торрент bitcoin bitcoin сайты bazar bitcoin bitcoin руб bitcoin халява уязвимости bitcoin bitcoin динамика bitcoin farm bitcoin описание bitcoin earn daemon monero asic ethereum обмена bitcoin bitcoin site депозит bitcoin attack bitcoin fox bitcoin bitcoin qiwi
ecdsa bitcoin расчет bitcoin bitcoin код
вклады bitcoin To buy cryptocurrencies, you’ll need a 'wallet,' an online app that can hold your currency. Generally, you create an account on an exchange, and then you can transfer real money to buy cryptocurrencies such as Bitcoin or Ethereum. Here's more on how to invest in Bitcoin.bitcoin fees bitcoin заработок bitcoin metatrader bitcoin planet bitcoin dynamics bitcoin cloud ethereum монета ethereum пулы mercado bitcoin bitcoin безопасность mempool bitcoin bitcoin fpga monero ann bitcoin crash field bitcoin bye bitcoin bitcoin yen 1999–present: P2P networks (excluding early networks like Usenet or FidoNet; MojoNation %trump2% BitTorrent, Napster, Gnutella, eDonkey, Freenet, i2p etc.)казино bitcoin работа bitcoin bitcoin мастернода
вход bitcoin bitcoin payza ethereum pow ethereum cryptocurrency часы bitcoin ethereum habrahabr bitcoin vps bitcoin hyip
bitcoin price monero difficulty aml bitcoin bitcoin qr криптовалюта monero bestchange bitcoin bitcoin euro bitcoin difficulty ethereum com cryptocurrency arbitrage collector bitcoin ethereum перевод ротатор bitcoin порт bitcoin bitcoin lucky kaspersky bitcoin ethereum виталий ethereum 1070 bitcoin код faucet bitcoin
golden bitcoin bitcoin книга bitcoin путин bitcoin приложения trade cryptocurrency scrypt bitcoin платформа bitcoin nodes bitcoin tether provisioning
abi ethereum 8 bitcoin bitcoin visa
bitcoin продам qr bitcoin monero fee cryptocurrency chart bitcoin server
casinos bitcoin bitcoin магазин ethereum contracts куплю ethereum отзывы ethereum
bitcoin начало nem cryptocurrency вики bitcoin bitcoin лотерея
ethereum контракт bitcoin лучшие monero free bitcoin zona капитализация bitcoin bitcoin trend
сокращение bitcoin ssl bitcoin bitcoin weekly bitcoin matrix bitcoin land daily bitcoin wallet tether The software is easy to use and well-integratedTo prove you did some extra work to create a block, you must create a hash of the block header which does not exceed a certain value. For example, if the maximum possible hash value is 2256 − 1, you can prove that you tried up to two combinations by producing a hash value less than 2255.Privacy and protection against spyingрасчет bitcoin datadir bitcoin
stake bitcoin blogspot bitcoin ann ethereum Putting 1-5% of a portfolio into Bitcoin can potentially improve risk-adjusted returns as a non-correlated asset. In the most bullish case, it could go up 10-20x or more, including in an environment where stocks and many other assets decrease in value. In a bearish case, it could lose value or even go to zero.bitcoin отследить bitcoin monkey bitcoin mixer ico monero monero windows bitcoin pizza 33 bitcoin bitcoin экспресс bitcoin кликер bitcoin vip bitcoin crypto rpc bitcoin bitcoin super bitcoin авто bitcoin заработать matteo monero bitcoin cz ethereum картинки bitcoin purchase валюта monero bitcoin фильм bitcoin protocol биткоин bitcoin кошелек ethereum bitcoin автоматически tether пополнение panda bitcoin ethereum кошельки moneybox bitcoin ethereum stats topfan bitcoin bitcoin рейтинг bitcoin slots bitcoin youtube adc bitcoin bitcoin token bitcoin china работа bitcoin китай bitcoin bitcoin сигналы programming bitcoin bitcoin программирование bitcoin icon bitcoin tor ethereum stats abi ethereum usb tether buy ethereum bitcoin laundering
mastering bitcoin config bitcoin etherium bitcoin
ethereum bitcointalk moneybox bitcoin отследить bitcoin bitcoin wikileaks майнить bitcoin ethereum dark bitcoin экспресс bitcoin конференция credit bitcoin bitcoin broker neo bitcoin валюта tether bitcoin people bitcoin конвектор bitcoin habrahabr ethereum usd bitcoin автомат bitcoin change bitcoin advertising bitcoin адрес
bitcoin price биржа bitcoin locate bitcoin 5Early 2021 Bitcoin boomBitcoin relies on two underlying mechanisms in order to function – the blockchain and the mining process. seed bitcoin bitcoin delphi bitcoin nodes pirates bitcoin ethereum доходность bitcoin символ андроид bitcoin теханализ bitcoin bitcoin количество solo bitcoin bitcoin 99 neo bitcoin иконка bitcoin ethereum купить майнинга bitcoin bitcoin адрес bitcoin rt world bitcoin email bitcoin money bitcoin
бесплатно ethereum bitcoin бизнес fork bitcoin bitcoin mine 2018 bitcoin bitcoin weekly trade cryptocurrency rx560 monero bitcoin grafik валюта bitcoin hacking bitcoin курс bitcoin blue bitcoin bitcoin com смесители bitcoin monero proxy trade cryptocurrency bitcoin etf amazon bitcoin бутерин ethereum bitcoin online иконка bitcoin frontier ethereum
майнить monero bitcoin hype No one knows what will become of bitcoin. It is mostly unregulated, but some countries like Japan, China and Australia have begun weighing regulations. Governments are concerned about taxation and their lack of control over the currency.Bitcoin: A Financial Institution Eliminating The Needbitcoin dice bitcoin goldman
moto bitcoin bitcoin blue bitcoin drip bitcoin символ coinmarketcap bitcoin приложение bitcoin
nem cryptocurrency ethereum asic conference bitcoin
сборщик bitcoin iso bitcoin
калькулятор monero future bitcoin freeman bitcoin
платформы ethereum bitcoin central
hacking bitcoin ethereum contracts keystore ethereum stock bitcoin bitcoin основатель wallets cryptocurrency total cryptocurrency
moto bitcoin cryptocurrency dash обновление ethereum sportsbook bitcoin bitcoin elena cryptocurrency bitcoin community bitcoin daemon
monero gpu bitcoin png количество bitcoin
prune bitcoin bitcoin sha256 bitcoin приложения
bitcoin shop reklama bitcoin reklama bitcoin bitcoin trader
bitcoin 4000 block bitcoin cryptocurrency magazine bitcoin preev bitcoin математика key bitcoin bitcoin реклама ethereum сегодня bitcoin nodes ethereum краны monero пулы bitcoin okpay ethereum сбербанк ставки bitcoin monero сложность armory bitcoin nanopool ethereum криптовалюта tether bitcoin virus
bitcoin майнеры bitcoin lurk bitcoin reward сколько bitcoin bitcoin принцип lootool bitcoin bitcoin service faucets bitcoin mac bitcoin bitcoin lurk monero алгоритм
bitcoin сложность bitcoin лучшие кошель bitcoin kraken bitcoin bitcoin txid bitcoin machine калькулятор bitcoin цена ethereum bitcoin win surf bitcoin bitcoin бесплатно forum ethereum рубли bitcoin monero *****uminer краны monero With the Segregated Witness upgrade, such instances can not happen again. This is because the witness signatures are moved outside of the transaction block into an extended block, and altering the witness signature won’t affect the transaction ID.Since the transaction malleability issue is fixed, Segregated Witness also enables the proper functioning of second-layer scalability solutions on the Bitcoin protocol, such as the Lightning Network.Serve as a platformhalf bitcoin
шрифт bitcoin bitcoin wallpaper
смесители bitcoin bitcoin switzerland bitcoin legal технология bitcoin An illustration of characters in a social space dedicated to Ethereum with a large ETH logoAn illustration of characters in a social space dedicated to Ethereum with a large ETH logoWelcome to Ethereumbitcoin cloud получить ethereum gas ethereum ethereum vk ethereum прогноз bitcoin 2017 сбор bitcoin
android tether
unconfirmed bitcoin grayscale bitcoin bitcoin market bitcoin google monero график bitcoin auto
magic bitcoin
programming bitcoin bitcoin kurs робот bitcoin андроид bitcoin donate bitcoin bitcoin иконка bitcoin переводчик bitcoin gpu trade cryptocurrency ethereum addresses p2pool ethereum бутерин ethereum loan bitcoin ethereum btc bitcoin de bitcoin india flex bitcoin ethereum dao mixer bitcoin робот bitcoin ico monero ethereum прогноз bitcoin converter airbitclub bitcoin daemon bitcoin tether usb ethereum валюта matrix bitcoin capitalization bitcoin finney ethereum bitcoin кликер форумы bitcoin truffle ethereum проблемы bitcoin bitcoin info bitcoin 4 bitcoin nachrichten bitcoin gambling korbit bitcoin the cost of gas expended within the block by the transactions included in the blockmatrix bitcoin A screenshot of the coinbase.com Bitcoin trading dashboard shows the changing values of Bitcoin cryptocurrency.bitcoin spinner bitcoin usa se*****256k1 ethereum подтверждение bitcoin bitcoin сбербанк bitcoin prosto bitcoin torrent капитализация ethereum remix ethereum instaforex bitcoin ethereum клиент работа bitcoin bitcoin genesis ethereum асик ethereum forks fasterclick bitcoin взлом bitcoin
phoenix bitcoin bitcoin ммвб The users who check the transaction to see whether it’s valid or not are known as miners. After this is done, the transaction and several others are added to the blockchain, where the details cannot be changed. Bitcoin vs. Ethereumbitcoin лучшие
bitcoin fund bitcoin nvidia значок bitcoin Multipools switch between different altcoins and constantly calculate which coin is at that moment the most profitable to mine. Two key factors are involved in the algorithm that calculates profitability, the block time, and the price on the exchanges. To avoid the need for many different wallets for all possible minable coins, multipools may automatically exchange the mined coin to a coin that is accepted in the mainstream (for example bitcoin). Using this method, because the most profitable coins are being mined and then sold for the intended coin, it is possible to receive more coins in the intended currency than by mining that currency alone. This method also increases demand on the intended coin, which has the side effect of increasing or stabilizing the value of the intended coin.Cryptocurrency walletпродать monero On 22 January 2018, South Korea brought in a regulation that requires all the bitcoin traders to reveal their identity, thus putting a ban on anonymous trading of bitcoins.decred cryptocurrency PC: 0 STACK: MEM: , STORAGE: bitcoin hunter instant bitcoin ethereum виталий кошель bitcoin котировки bitcoin bitcoin получить
ethereum addresses
raspberry bitcoin bitcoin today
bitcoin metatrader antminer bitcoin Where transactions are processedbitcoin money ethereum ico bitcoin рейтинг
buy tether перспективы bitcoin explorer ethereum