קאווע שטיבל

In general relativity there exists no meaningful local expression for gravitational stress-energy and thus there is no meaningful local energy conservation law which leads to a statement of energy conservation

We end by noting that, according to Einstein, God is subtle, but He is not malicious. That may be so, but His influence on falling toast clearly leaves much to be desired

According to Martin Gardner, Abdelkader’s mental acrobatics create ‘a consistent physics that cannot be falsified by any conceivable observation or experiment!’ But how can something so stupid not be falsifiable? Such a question treats unfalsifiability as an alibi rather than a liability. It assumes, naively, that models are innocent until proven guilty

Theism fails as an explanation. Even if you think the universe is finely-tuned and you don’t think that naturalism can solve it, theism certainly does not solve it. If you thought it did, if you played the game honestly, what you would say is, “Here is the universe that I expect to exist under theism. I will compare it to the data and see if it fits.” What kind of universe would we expect? I’ve claimed that over and over again the universe we would expect matches the predictions of naturalism not theism. So the amount of tuning, if you thought that the physical parameters of our universe were tuned in order to allow life to exist, you would expect enough tuning but not too much. Under naturalism, a physical mechanism could far over-tune by an incredibly large amount that has nothing to do with the existence of life and that is exactly what we observe. For example, the entropy of the early universe is much, much, much, much lower than it needs to be to allow for life

As Robin Collins has pointed out, even if a general low entropy condition is not necessary for our existence, it is necessary for the discoverability of the universe. God hasn’t given us an instruction manual about how the world works. But what he has done is make a world which is susceptible to rational exploration and discovery. And if God wanted to make a universe discoverable by embodied, conscious agents, he might well make it in such a low entropy condition

What causes the universe to pop out of nothing? No cause is needed

When physicists or theologians ask me about the BGV theorem, I am happy to oblige. But my own view is that the theorem does not tell us anything about the existence of God. A deep mystery remains. The laws of physics that describe the quantum creation of the universe also describe its evolution. This seems to suggest that they have some independent existence

What exactly this means, we don’t know. And why are these laws the ones we have? Why not other laws? We have no way to begin to address this mystery

There’s a deep philosophical difference between us. I claim that a consistent, complete model that fits the data accounts for what we see in the world is a success. There’s no right that we have to demand more than that, and I believe that Dr. Craig’s response was, “Yes there is.” I don’t think this counts as a very good response. It’s a very difficult thing because the universe is different than our everyday experience. That doesn’t sound like a surprising statement but we really need to take it to heart. To look at a modern cosmological model and say, “Yes, but what was the cause?” is like looking at someone taking pictures with an iPhone and saying, “But where does the film go?” It’s not that the answer is difficult or inscrutable; it’s completely the wrong question to be asking. In fact it’s a little technical, but I think it’s worth getting it right. Why should we expect that there are causes or explanations or a reason why in the universe in which we live? It’s because the physical world inside of which we’re embedded has two important features. There are unbreakable patterns, laws of physics — things don’t just happen, they obey the laws — and there is an arrow of time stretching from the past to the future. The entropy was lower in the past and increases towards the future. Therefore, when you find some event or state of affairs B today, we can very often trace it back in time to one or a couple of possible predecessor events that we therefore call the cause of that, which leads to B according to the laws of physics. But crucially, both of these features of the universe that allow us to speak the language of causes and effects are completely absent when we talk about the universe as a whole. We don’t think that our universe is part of a bigger ensemble that obeys laws. Even if it’s part of the multiverse, the multiverse is not part of a bigger ensemble that obeys laws. Therefore, nothing gives us the right to demand some kind of external cause

The idea that our intuitions about cause and effect that we get from the everyday experience of the world in this room should somehow be extended without modification to the fundamental nature of reality is fairly absurd

Now there’s a theorem by Alan Guth, Arvind Borde, and Alex Vilenkin that says the universe had a beginning. I happen to have Alan Guth right here. One of the authors of the Borde-Guth-Vilenkin Theorem. He says, “I don’t know whether the universe had a beginning. I suspect the universe didn’t have a beginning. It’s very likely eternal but nobody knows.” Now how in the world can the author of the Borde-Guth-Vilenkin theorem say the universe is probably eternal? Because the theorem is only about classical descriptions of the universe not about the universe itself

The universe is different than things inside the universe. As I tried to explain, there is a reason why there are reasons why. There are reasons why in our everyday life it is perfectly correct to speak a language of causation and explanation and invention and creation, and when you look carefully what those reasons are, they don't apply to the universe. The universe isn't part of a bigger structure in which there are patterns, evolution laws, arrows of time, expectations for what should happen

I do not think that if the universe has a first moment in time that means there is any sort of eternal or preexisting conditions or rules or laws or anything like that. It simply means that our best and maybe the correct description of the cosmos is one that had a first moment in time. The question is, can that be self-contained in the sense that I'm using it, which is that if I write down the equations and the conditions and so forth that describe the universe with an earliest moment, am I done? Are there questions that I might have about that universe that cannot be answered by that formalism? And I think there is no obstacle whatsoever to coming up with such models. And so I would simply un-ask the question. I would say, no, there aren’t preexisting or eternal rules. There is the universe and the universe has a first moment and the universe obeys rules during those moments when the universe exists. During those moments when the universe does not exist, there are no moments, there is no time, there are no rules

Also, I don't think it's the right thing to say that the Borde-Guth-Vilenkin theorem says that the classical universe had a beginning. The part of the universe that we can describe using classical space-time had a beginning just like this room had a beginning. But that says nothing at all about the universe as a whole. Alan Guth does not believe the universe is eternal because it's a hunch or personal preference. It's because he's a scientist and he's trying to develop models that fit the data. We have puzzles in cosmology. Given his knowledge of the models, he believes the best way forward, the most promising way forward, are the models in which the universe is eternal. He knows that there is a theorem saying if you obey the rules of quantum mechanics under the assumptions I gave the universe must be eternal. He knows the early universe had a low entropy and the best possible explanation we currently have for dynamically explaining that involves an eternal cosmology. This is exactly how scientists work all the time

When Dr. Carroll says, “The universe is different than our experience,” this is really committing what Alexander Pruss calls the taxi-cab fallacy, that is to say, you go with the causal principle until you reach your desired goal and then you think you can just dismiss it like a hack because you don’t want there to be a cause of your entity – the universe. But if the universe came into existence, if the universe is not eternal, then surely it would need to have a cause. In fact, to deny this is unscientific because the whole project of contemporary cosmogony is to try to find what is the cause of the universe! So on his principle, it would be a science-stopper and would destroy his very field of expertise

I haven’t spoken to Alan Guth about the theorem. I have spoken with Vilenkin. I think that they would agree that the theorem under this single stated condition shows that classical space-time did have to have a beginning, and Guth doesn't dispute that. He says that. Now when he holds up a little sign saying “I think the universe is probably eternal,” that's probably just reflecting a sort of personal preference or skepticism that maybe we'll find a quantum theory or something that will be a non-classical model that will restore the eternality of the universe. That could be his predisposition or his hope or hunch or something of that sort. But in terms of scientific evidence, there's no evidence at all that the universe is beginningless. As Vilenkin said, all of the evidence is on one side of the scale, that the universe began to exist, and there are no models of a beginningless universe that are successful. So I don't know exactly what he meant by that. But I think we do know that the implications of the theorem are that any model that falls under its single condition will have a beginning to classical space-time. And also I would say that models that don't fall under that condition usually always have other problems, as well. And then I argued that this quantum gravity regime, if there was such a thing that preceded the classical space-time regime, that marked the beginning of the universe, if the universe didn't begin at the classical space-time boundary

One sometimes hears the claim that the Big Bang was the beginning of both time and space; that to ask about spacetime “before the Big Bang” is like asking about land “north of the North Pole.” This may turn out to be true, but it is not an established understanding. The singularity at the Big Bang doesn’t indicate a beginning to the universe, only an end to our theoretical comprehension. It may be that this moment does indeed correspond to a beginning, and a complete theory of quantum gravity will eventually explain how the universe started at approximately this time. But it is equally plausible that what we think of as the Big Bang is merely a phase in the history of the universe, which stretches long before that time – perhaps infinitely far in the past. The present state of the art is simply insufficient to decide between these alternatives; to do so, we will need to formulate and test a working theory of quantum gravity

The issue of whether or not there actually is a beginning to time remains open. Even though classical general relativity predicts a singularity at the Big Bang, it’s completely possible that a fully operational theory of quantum gravity will replace the singularity by a transitional stage in an eternal universe. A variety of approaches along these lines are being pursued by physicists: bouncing cosmologies in which a single Big Crunch evolves directly into our observed Big Bang, cyclic cosmologies in which there are an infinite number of epochs separated by Big Bangs, and baby-universe scenarios in which our Big Bang arises spontaneously out of quantum fluctuations in an otherwise quiet spacetime. There is no way to decide between beginning and eternal cosmologies on the basis of pure thought; both possibilities are being actively pursued by working cosmologists, and a definitive judgment will have to wait until one or the other approach develops into a mature scientific theory that makes contact with observations

A provocative way of characterizing “beginning” cosmologies is to say that “the universe was created from nothing.” Much debate has gone into deciding what this claim is supposed to mean. Unfortunately, it is a fairly misleading natural-language translation of a concept that is not completely well-defined even at the technical level. Terms that are imprecisely defined include “universe,” “created,” “from,” and “nothing.” (We can argue about “was”)

Nothing in the fact that there is a first moment of time, in other words, necessitates that an external something is required to bring the universe about at that moment. As Hawking put it in a celebrated passage:

So long as the universe had a beginning, we could suppose it had a creator. But if the universe is really self-contained, having no boundary or edge, it would have neither beginning nor end, it would simply be. What place, then, for a creator?

Georges Lemaitre himself, the Belgian priest and physicist who in the 1920’s developed the original Big Bang model (which he called the “primeval atom”), resolutely declined to draw any theological conclusions from his theory, preferring to keep his religious beliefs strictly separate from his scientific work. He later served as a member of the Pontifical Academy of Sciences, and advised Pope Pius against using scientific discoveries as evidence in theological arguments

. . .

There is another angle often taken by natural theologians in explaining God’s usefulness to cosmology: that, whatever the facts of the world might be and whatever patterns they might follow, only a divine being can offer a “reason why” things are that way, over and above the facts and patterns themselves

These ideas all arise from a conviction that, in various contexts, it is insufficient to fully understand what happens; we must also provide an explanation for why it happens – what might be called a “meta-explanatory” account.
It can be difficult to respond to this kind of argument. Not because the arguments are especially persuasive, but because the ultimate answer to “We need to understand why the universe exists/continues to exist/exhibits regularities/came to be” is essentially “No we don’t.” That is unlikely to be considered a worthwhile comeback to anyone who was persuaded by the need for a meta-explanatory understanding in the first place

Granted, it is always nice to be able to provide reasons why something is the case. Most scientists, however, suspect that the search for ultimate explanations eventually terminates in some final theory of the world, along with the phrase “and that’s just how it is.” It is certainly conceivable that the ultimate explanation is to be found in God; but a compelling argument to that effect would consist of a demonstration that God provides a better explanation (for whatever reason) than a purely materialist picture, not an a priori insistence that a purely materialist picture is unsatisfying

Why are some people so convinced of the need for a meta-explanatory account, while others are perfectly happy without one? I would suggest that the impetus to provide such an account comes from our experiences within the world, while the suspicion that there is no need comes from treating the entire universe as something unique, something for which a different set of standards is appropriate

In Aristotle’s Metaphysics, he suggested the need for an “unmoved mover” to explain the motion of ordinary objects. That makes sense in the context of Aristotle’s physics, which was fundamentally teleological: objects tended toward their natural place, which is where they wanted to stay. How, then, to account for all the motion we find everywhere around us? But subsequent developments in physics – conservation of momentum, Newton’s laws of motion – changed the context in which such a question might be asked. Now we know that objects that are moving freely continue to move along a uniform trajectory, without anything moving them. Why? Because that’s what objects do. It’s often convenient, in the context of everyday life, for us to refer to this or that event as having some particular cause. But this is just shorthand for what’s really going on, namely: things are obeying the laws of physics

Likewise for the universe. There is no reason, within anything we currently understand about the ultimate structure of reality, to think of the existence and persistence and regularity of the universe as things that require external explanation. Indeed, for most scientists, adding on another layer of metaphysical structure in order to purportedly explain these nomological facts is an unnecessary complication

מי אני האט געשריבן: ↑דאנערשטאג יוני 01, 2023 6:34 pm ‏דא זאגט דער פיזיקער דר. דניאל ווייטסאן אז די עקספּענשאן פונעם יוּניווערס, וואס דאס ברענגט מער טונקעלע ענערגיע (וואס טוהט ווייטער שטופן די עקספּענשאן, וחוזר חלילה) און טוהט דאדורך אויך רעדשיפטן פאטאנס וממילא פארלירן זיי ענערגיע (אויף אסאך א קלענערן פארנעם), באדייט אז קאַנסערוועישאן פון ענערגיע האלט נישט. ער זאגט אז דאס איז מכח דעם אז די עקספּענשאן פון די יוּניווערס טוהט טאקע צוברעכן דעם סימעטרי פון ספּעיסטיים אין וועלכעס די קאַנסערוועישאן פון ענערגיע איז אָנגעוואנדן.

ער זאגט אז עס איז למעשה קאנטראווערסיאנאל און עס זענען דא פיזיקער וואס טענה׳ן אז די עקספּענשאן פון די יוּניווערס איז גורם נעגאטיווע גראוויטעישאנעל (פעלד) ענערגיע וואס טוהט אָפסעטן די טונקעלע ענערגיע וואס קומט צו, וממילא איז נאך אלס דא קאַנסערוועישאן פון ענערגיע.

ואם שנתיר לעצמינו מה שנמצא בקצת מאמרים לחכמינו ז״ל, הביאם הרב המורה, ולא ראינו חולק עליהם. אמרם (ב״ר פ״ג): ״מלמד שהיה בונה עולמות ומחריבן״. ומהם אמרם: ״מלמד שהיה סדר זמנים קודם לכן״. הכוונה מהם לפי מה שנראה — החידוש התמידי; אלא שהיו הוים בעת ידוע ונפסדים בעת ידוע, אם בהתהוות האישים והפסדם, ואם להיות כל אחד מהם הולך מהאחר מדריגת השלימות. ואפשר שזה שאנחנו בו ישאר נצחי, ואפשר שיפסד ויבא אחריו עולם אחר, הולך מזה מהלך השלימות, כמדריגת החי מהצומח. כי בזה דלתי החקירה נעולות, והדברים עתיקים למקבלי האמת. ואם היה מהחכמים שהרחיקו מאד הפסד העולם מצד העיון, הנה יתבאר בקלות שאין בכל מה שאמרו שיחייב מה שחייבו.

Thermodynamics is a funny subject. The first time you go through it, you don't understand it at all. The second time you go through it, you think you understand it, except for one or two small points. The third time you go through it, you know you don't understand it, but by that time you are so used to it, it doesn't bother you any more

כי האמונה שיש לו בזה חוזק המציאות הוא מעלה אלקית, כי דברים החמרים חלושי המציאות מקבלים שינוי תמיד ואין חוזק להן, אבל מאחר שיש בו האמונה והוא דבר חזק שלא יהרהר אנה ואנה, לכך הוא דבר אלקי אינו גשמי שכל דבר אלקי לא יקבל שינוי כלל. ובשביל זה ראוי שתשרה עליו השכינה להיות דבק בו הנבדל. וזהו שאמרו ז״ל בפרק כל כתבי (שבת קיט:) העונה אמן בכל כוחו פותחין לו שערי גן עדן דכתיב (ישעיה כו ב) פתחו שערים ויבא גוי צדיק שומר אמונים, אל תקרא אמונים אלא אמנים. והוא לטעם שהתבאר למעלה, שראוי להיות נכנס במעלת הגן עדן, כי דברים המשתנים הם רעים בעבור שכל שינוי רע. אבל מי שחזק באמונה, בשביל החוזק שיש לו ואין מקבל שינוי באמונתו, הרי נבדל משינוי אשר הוא לחמרים. וזהו כניסה לגן עדן שהוא מתרחק מן השינוי והתמורה שהוא רע, ולכן פותחין לו שערי גן עדן שאין שם רק עדן ושמחה ורחוק מן התפעלות ועצב. וכל ענין זה בשביל החוזק שיש לו באמונה ואין לו השתנות.

מי אני האט געשריבן: ↑דאנערשטאג מערץ 17, 2022 12:56 am בנוגע פּרעשור און פלוּאידס איז דא בּערנאָלי׳ס פּרינציפּ. דאס לויטעט אז ווי שנעלער א פלוּאיד גייט אלס ווייניגער איז די פּרעשור דערפון. דאס לויטעט מער פונקטליך אז ווען איך נעם האלב פון דאס שנעלקייט דערפון סקווערד, איך לייג צו דערצו די עקסעלערעישאן פון גרעוויטי[32.2 פיס שנעלער יעדע סעקונדע] טיימס ווי הויך דאס איז ביחס קעגן ווי גרעוויטי שלעפט דאס, און איך לייג צו דערצו די פּרעשור דערפון ווען עס ווערט דיוויידעד ביי די דענסיטי דערפון [די צאל מאסע דערין רעלאטיוו צו די וואליוּם דערפון], וועט אלס אויסקומען צו די זעלבע נומער נישט קיין חילוק אין די פלוּאיד.

מי אני האט געשריבן: ↑מוצ"ש נאוועמבער 13, 2021 7:40 pmלגבי די עררוֺי פון צייט טענה׳ט דר. וויקטאר סטענגער אז עפ״י פיזיקס/מאטעמאטיקס טאמער נעמט מען אָן אז בעצם האט די גאנצע יוּניווערס א פּאזיטיווע קוּרוועטשוּר, דאן טאמער גייט מען צוריקצווועגס ביז צום פריער-דערמאנטן פּלאנק ספיר/עפאכע/צייט דאן, עפ״י קוואנטום טאָנעלינג, ווערט דאס פארדעם אלעם אן אנדערע שפיגל יוּניווערס וואס ארבעט מיט א נעגאטיווע דירעקציע פון צייט רעלאטיוו צו אונז; זייער עררוֺי פון צייט איז פארקערט.
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‏דאס דערמאנט פונעם טענעט פילם וואס שפילט ארום מיט צייט אויף צוריקצווועגס עפ״י ענטראָפּי.

מי אני האט געשריבן: ↑דינסטאג סעפטעמבער 05, 2023 8:04 am עס איז אינטרעסאנט צו באמערקן אז אין מאטעמאטיקס האט דער מאטעמאטיקער דר. טעאדאר מאצקין געזאגט (ועפ״י רעמסי טעאריע) אז:

Complete disorder is impossible

און עס איז דאך יתכן אז די וועלט איז מאטעמאטיקס.

In all chaos there is a cosmos. In all disorder there is a secret order

מי אני האט געשריבן: ↑זונטאג מאי 24, 2020 5:06 pm

די דריטע געזעץ

דאס וואס מ׳האט פריער צוגעענדיגט די צווייטע געזעץ און איבער קעלווינס פירט אריין צום דריטן געזעץ. דאס לויטעט אז אויב קומט מען אן (אין א קריסטאל לעטיס וואו עס איז שייך אז די אטאמען זאלן זיך אויסשטעלן אין א פונקטליכן ערעי/סדר) צו אבסאלוט זערא וועט די ענטראָפּי אויך זיין זערא. דאס איז ווייל דעמאלטס איז נישטא קיין ענערגיע וואס זאל וועלען גיין ערגעץ.

Some materials (e.g., any amorphous solid) do not have a well-defined order at absolute zero. In these materials (e.g., glass), some finite entropy also remains at absolute zero because the system’s microscopic structure (atom by
atom) can be arranged in different ways (W ≠ 1). This constant entropy is known as the residual entropy.

Crystalline systems approach zero entropy state, while amorphous systems do not reach a state of 0 entropy, rather just a state of constant entropy. Most solids would be classified under amorphous, and hence we can say most will not have zero entropy at 0 K. Glasses and gels are some examp.