L’UNIVERSO NATO DAL NULLA

Riccardo Mariani

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L’UNIVERSO NATO DAL NULLA

C’è qualcosa che non quadra nell’ipotesi del salto quantico: la funzione d’onda, infatti, descrive lo stato di qualcosa come sovrapposizione di stati incompatibili ognuno con il suo peso di probabilità (ad esempio gli stati ‘testa’ e ‘croce’ di una moneta non truccata hanno peso rispettivo del 50% ciascuno). La fluttuazione quantistica non è altro che il collassare di questa funzione in uno degli stati più improbabili che la compongono. Ebbene, difficile considerare questo “qualcosa” che precede la fluttuazione e che possiamo descrivere tanto puntualmente (al punto da consentirci previsioni pratiche molto attendibili) come un “nulla”. Ogni campo, anche quello che definisce il vuoto, è comunque qualcosa.

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L'universo dal nulla. Le rivoluzionarie scoperte che hanno cambiato le nostre basi scientifiche

L'universo dal nulla. Le rivoluzionarie scoperte che hanno cambiato le nostre basi scientifiche

Mi piaceVedi altre reazioni

john lennox god and hawking (mia critica su amazon)

Secondo John Lennox non è corretto contrapporre scienza e religione, il vero conflitto filosofico è tra ateismo e teismo, con gli scienziati che militano su entrambi i fronti. L’agile pamphlet prende di mira ad alzo zero un saggio scritto nel 2010 dai fisici e divulgatori scientifici Stephen Hawking e Leonard Mlodinow in cui ci si pronuncia chiaramente in favore di un’origine spontanea dell’universo: “… because there is a law such as gravity, the universe can and will create itself from nothing”.
Prima botta: secondo JL, SH ha un’idea inadeguata della filosofia (come del resto qualsiasi scientista): dice che ormai è morta e poi scrive un libro che per tre quarti espone (zoppicanti) argomenti filosofici. SH sarebbe un “filosofo a sua insaputa”, oltretutto un filosofo mediocre visto che così facendo si allontana dal suo ambito di competenza. Un errore evitato con cura nel suo best seller “Storia del tempo”. Dovrebbe, al limite, liquidare come insensate certe domande, e invece cerca di rispondervi con i pochi strumenti messi a disposizione della scienza andando incontro ad inevitabili forzature. 
SH, inoltre, possiede anche un’inadeguata concezione di Dio. Riesce a pensarlo solo come “tappabuchi”, ovvero come colui che fa “ruggire il tuono” spaventando l’uomo che da terra non sa darsi spiegazioni. Ma un Dio del genere è proprio cio’ a cui si oppone il Dio creatore di Mosè, che SH, evidentemente, non comprende confondendo Dio con la deificazione della natura tipica delle religioni politeiste.
La tesi di fondo di SH (“Because there is a law of gravity, the universe can and will create itself out of nothing”)    è anche inficiata da diversi errori logici. Innanzitutto è d’uopo chiedersi cosa intenda SH per “nothing”: se esiste una “legge di gravità” evidentemente non siamo in presenza del “nulla” dei filosofi. I sospetti crescono poi se si nota che a volte i fisici fanno riferimento al cosiddetto “quantum vacuum” che è cosa ben diversa dal nulla che precede la creazione, SH sembrerebbe sorvolare bellamente su questa differenza chiave. La posizione assunta da SH assomiglierebbe pericolosamente a quella di  Peter Atkins, l’ideatore del “Cosmic Bootstrap”, ovvero un modello che ci lascia perplessi almeno quanto la lettura  delle avventure del Barone di Munchausen. Se dovessimo davvero scegliere tra “l’ipotesi Dio” e “l’ipotesi Bootstrap”, aveva a suo tempo osservato Keith Ward, sembrerebbe non esserci competizione. 
JL si chiede anche se SH abbia ben capito cosa sia una “legge di natura” visto che nella sua tesi ne parla come di un agente più che come un descrittore: “la forza di gravità creerebbe il mondo”. Dopo un excursus che arriva a Cartesio veniamo a sapere che la “legge di natura” è una legge che ricaviamo dall’osservazione di regolarità nella natura e che ci consentono di fare previsioni affidabili a certe condizioni date. Ebbene, una roba del genere, al limite, descrive la natura, non la crea. Come può dunque SH affermare che dire “Because there is a law of gravity, the universe can and will create itself out of nothing”? O la legge di natura di cui si parla sta “descrivendo” qualcosa, ma allora prima del passaggio dal nulla all’essere c’è qualcosa (che è descritto) anziché niente, o la legge di natura sta creando qualcosa dal nulla, e allora c’è l’incomprensione di cosa sia una legge di natura di chi fa questa ipotesi. Da Galileo a Newton la scienza ha usato la legge di natura come descrittore e Dio come agente, ora SH utilizza la legge di natura sia come descrittore che come agente. La cosa meraviglia JL, per usare un eufemismo.
In passato molti scienziati hanno affermato con orgoglio che ai loro modelli “Dio non serviva”, e ci credo, replica JL, evitavano con cura le domande più importanti! SH invece vorrebbe affrontarle di petto senonché non possiede strumenti adeguati per rispondere in un modo che sia convincente a tutto tondo.

Finisco qui il mio resoconto anche se il libro procede su questa falsariga. E’ un libro di comprensione abbastanza facile, forse fin troppo facile, le critiche sono talmente chiare che vengono dei dubbi: ma davvero SH è tanto ingenuo come sembrerebbe dal resoconto fornito? Certo, ascoltando alcuni scienziati filosofare o parlare di politica a volte ci si demoralizza, ma SH è sempre stato un mito riconosciuto da tutti. Non è che forse le posizioni di SH sono state troppo caricaturizzate? Ecco, per rispondere non resta che leggersi “Il grande disegno”, e questa sollecitazione forse è la cosa più meritoria del libro di Lennox.

2 God or the laws of nature? - God and Stephen Hawking: Whose Design Is It Anyway? by John Lennox

2 God or the laws of nature? - God and Stephen Hawking: Whose Design Is It Anyway? by John Lennox - #quantumvacuumenulla #laleggedinaturaeilnulla #bootstrap #laleggecomeagente #analogiadelmotore #lequattrocausediaristotele

2 God or the laws of nature?Read more at location 287

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A matter of logic: a self-creating universe?Read more at location 289

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conclusions of The Grand Design is: “Because there is a law of gravity, the universe can and will create itself out of nothing.”Read more at location 290

Note: TESI DI SH Edit

The first question to ask is: what does Hawking mean when he uses the word “nothing” in the statement “the universe can and will create itself out of nothing”? Note the assumption in the first part of that statement: “Because there is a law of gravity…” Hawking assumes, therefore, that a law of gravity exists.Read more at location 296

Note: LA GRAVITÀ E IL NULLA Edit

gravity or a law of gravity is not “nothing”,Read more at location 300

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Indeed, one might add for good measure the fact that when physicists talk about “nothing”, they often appear to mean a quantum vacuum, which is manifestly not nothing. In fact, Hawking is surely alluding to this when he writes: “We are a product of quantum fluctuations in the very early universe.”Read more at location 303

Note: IL NULLA E IL QUANTUM VACUUM Edit

If we say “X creates Y”, we presuppose the existence of X in the first place in order to bring Y into existence.Read more at location 313

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therefore, we say “X creates X”, we imply that we are presupposing the existence of XRead more at location 314

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To presuppose the existence of the universe to account for its own existence sounds like something out of Alice in Wonderland, not science.Read more at location 316

Note: ALICE Edit

He says the universe comes from a nothing that turns out to be a something (self-contradiction number one), and then he says the universe creates itself (self-contradiction number two).Read more at location 318

Note: 2 CONTRADDIZIONI IN 2 RIGHE Edit

His notion that a law of nature (gravity) explains the existence of the universe is also self-contradictory, since a law of nature, by definition, surely depends for its own existence on the prior existence of the nature it purports to describe.Read more at location 320

Note: PRIMA LA LEGGE O PRIMA LA NATURA? PLATONICI O IMMANENTISTI? Edit

triple self-contradiction.Read more at location 323

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Hawking is echoing the language of Oxford chemist Peter Atkins (also a well-known atheist), who believes that “space-time generates its own dust in the process of its own self-assembly”.23 Atkins dubs this the “Cosmic Bootstrap”Read more at location 324

Note: BOOTSTRAP Edit

a person lifting himself by pulling on his own bootlaces.Read more at location 327

Note: BARONE DI MONCHAUSEN Edit

“Between the hypothesis of God and the hypothesis of a cosmic bootstrap, there is no competition. We were always right to think that persons, or universes, who seek to pull themselves up by their own bootstraps are forever doomed to failure.”Read more at location 330

Note: KEITH WARD Edit

it is important to point out that they are not statements of science, and any statement, whether made by a scientist or not, should be open to logical analysis.Read more at location 335

Note: FILOSOFIA NN SCIENZA Edit

The nature of the laws of natureRead more at location 341

Note: LEGGE DI NATURA Edit

Hawking points out that there was originally no clear distinction in Greek thought between human laws and the laws of nature;Read more at location 342

Note: GRECI Edit

idea that inanimate objects possessed minds and intentionality was espoused by Aristotle,Read more at location 344

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Hawking reminds us that it was Descartes (1596–1650) who first formulated the concept of the laws of nature in our contemporary sense.Read more at location 345

Note: CARTESIO Edit

rule that is based upon an observed regularity and provides predictionsRead more at location 347

Note: LEGGE DI NATURA Edit

A familiar example of such a law is “the sun rises in the east”. It is based on an observed regularity,Read more at location 349

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we have observed the sun to rise a thousand times in the past does not prove that it will rise again tomorrow. We have to add something like, “all things being equal”, “provided the sun does not explode”, etc.Read more at location 353

Note: COETERIS PARIBUS Edit

In other words, it is not enough to state Newton’s laws on their own. We need additionally to specify at least the range of conditions under which they are valid.Read more at location 358

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The origin of the laws of natureRead more at location 359

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What is the origin of these laws?Read more at location 362

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Hawking suggests that the traditional answer to the first question, given by the great pioneers of science like Galileo, Kepler, Descartes and Newton, is that the laws are the work of God. Hawking adds: “However, this is no more than a definition of God as the embodiment of the laws of nature.Read more at location 365

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another.”27 However, the God in whom Galileo, Kepler, Descartes and Newton believed wasRead more at location 368

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the intelligent Creator and upholder of the universe, who is a person and not a set of abstract laws.Read more at location 370

Note: IL DIO DI GALILEO ECC. Edit

God or the laws of physics?Read more at location 381

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Talking about M-theory (his chosen candidate for a final unifying theory of physics), Hawking writes: “M-theory predicts that a great many universes were created out of nothing. Their creation does not require the intervention of some supernatural being or god. Rather, these multiple universes arise naturally from physical law.”Read more at location 384

Note: L ALTERNATIVA A DIO Edit

Hawking ascribes creative power to physical law; but physical law is not an agent. Hawking is making a classic category mistake by confusing two entirely different kinds of entity: physical law and personal agency.Read more at location 389

Note: LA LEGGE AGENTE Edit

Suppose, to make matters clearer, we replace the universe by a jet engine and then are asked to explain it. Shall we account for it by mentioning the personal agency of its inventor, Sir Frank Whittle? Or shall we follow Hawking: dismiss personal agency, and explain the jet engine by saying that it arose naturally from physical law?Read more at location 392

Note: ANALOGIA DEL MOTORE Edit

It is self-evident that we need both levels of explanation in order to give a complete description. It is also obvious that the scientific explanation neither conflicts nor competes with the agent explanation: they complement one another.Read more at location 396

Note: COMPLEMENTO Edit

Sir Isaac Newton, a previous holder of the Lucasian Chair at Cambridge, did not make Hawking’s category mistake when he discovered his law of gravitation. Newton did not say: “Now that I have the law of gravity, I don’t need God.” What he did was to write Principia Mathematica, the most famous book in the history of science, expressing the hope that it would “persuade the thinking man” to believe in God.Read more at location 401

Note: NEWTON Edit

The laws of physics can explain how the jet engine works, but not how it came to exist in the first place.Read more at location 405

Note: RUOLO DELLA LEGGE Edit

Aristotle thought a great deal about these issues. He spoke about four different “causes”Read more at location 409

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material causeRead more at location 410

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then there is the formal cause – the concept, plan, theory,Read more at location 411

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Next there is the efficient cause – Sir Frank Whittle himself, who did the work.Read more at location 412

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Fourthly, and last in the list, there is the final cause – the ultimate purpose for which the jet engine was conceived and built:Read more at location 412

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Science, according to many scientists, concentrates essentially on material causation. It asks the “how” questions:Read more at location 414

Note: SCIENZA: COME Edit

But it does not ask the “why” question of purpose: why was the jet engine built?Read more at location 416

Note: PERCHÈ. SCOPO Edit

Whittle does not appear in the scientific account. To quote Laplace, the scientific account has “no need of that hypothesis”.29 Clearly, however, it would be ridiculous to deduce from this that Whittle did not exist. He is the answer to the question: why does the jet engine exist in the first place?Read more at location 417

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they claim that God is unnecessary, or doesn’t exist. They fail to see that their science does not answer the question as to why something exists rather than nothing, for the simple reason that their science cannot answer that question.Read more at location 422

Note: DIO NN SERVE! CERTO. SE NN TI FAI LE DOMANDE PIÙ IMPORTANTI... Edit

Much as I find it hard to believe, Hawking seems to wish to reduce all explanation to formal causes only. He claims that all that is necessary to create the universe is the law of gravity.Read more at location 431

Note: FORMALISMO Edit

to say that a theory or physical laws could bring the universe (or anything at all, for that matter) into existence is to misunderstand what theory and laws are.Read more at location 434

Note: CONFUSIONE FATALE Edit

the theories and laws cannot even cause anything, let alone create it.Read more at location 436

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Physical laws cannot create anything. They are a description of what normally happens under certain given conditions.Read more at location 445

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Similarly Newton’s law of gravitation does not create gravity or the matter on which gravity acts.Read more at location 447

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Another example of this basic misunderstanding of the nature of law is given by well-known physicist Paul Davies:Read more at location 455

Note: PAUL DAVIES Edit

for me it is much more inspiring to believe that a set of mathematical laws can be so clever as to bring all these things into being.”Read more at location 457

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C. S. Lewis grasped this issue, with characteristic clarity. Of the laws of nature he writes: They produce no events: they state the pattern to which every event – if only it can be induced to happen – must conform,Read more at location 463

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If Hawking were not as dismissive of philosophy he might have come across the Wittgenstein statement that the “deception of modernism” is the idea that the laws of nature explain the world to us, when all they do is describe structural regularities.Read more at location 481

Note: WITTGENSTEIN Edit

Richard Feynman, a Nobel Laureate in physics, takes the matter further: The fact that there are rules at all to be checked is a kind of miracle; that it is possible to find a rule, like the inverse square law of gravitation, is some sort of miracle.Read more at location 483

Note: MIRACOLO DELLA COMPRENSIONE Edit

The very fact that those laws can be mathematically formulated was for Einstein a constant source of amazementRead more at location 488

Note: MATEMATCA Edit

Allan Sandage, widely regarded as the father of modern astronomy, discoverer of quasars, and winner of the Crafoord Prize (astronomy’s equivalent of the Nobel Prize), is in no doubt about his answer: “I find it quite improbable that such order came out of chaos. There has to be some organizing principle. God to me is a mystery but is the explanation for the miracle of existenceRead more at location 498

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Big Bang theory, because, even if the non-believers don’t like it, the Big Bang resonates powerfully with the biblical narrative of creation. That is why, before theRead more at location 503

Note: BIG BANG