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Rethinking the origins of the universe

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Re: Rethinking the origins of the universe

#111

Post by scott_s »

aruggirello wrote: post #110
scott_s wrote: post #51

Earlier quoted context omitted.

I don't think that is a response to this work. That is dated February 1. He links to this paper's author, Laura Mersini-Houghton, but he links to a paper and blog post of hers from January. Reading that blog post ( http://backreaction.blogspot.com/2014/01/if-it-quacks-like-b... ), what she says seems to be in contradiction with the more recent paper she wrote ( http://arxiv.org/abs/arXiv:1409.1837 ). In her blog post…

I'm confused here. The mere existence of an event horizon - albeit a temporary one - should make a black hole! So "More specifically, we find that collapsing stars slow down their collapse right outside their horizon," by implying that a horizon DOES exist, simply doesn't cut it. Am I missing something?

I believe that's using the concept of a horizon. For an object of a particular mass, we can use our theory to tell us where the event horizon would be, if it collapses past that point. My understanding of this recent paper is that they are saying: it won't collapse past that point.

Re: Rethinking the origins of the universe

#112

Post by saalweachter »

vorg wrote: post #29
tfgg wrote: post #13

"In 1974, Stephen Hawking used quantum mechanics to show that black holes emit radiation. Since then, scientists have detected fingerprints in the cosmos that are consistent with this radiation, identifying an ever-increasing list of the universe’s black holes." Er, what? I don't think this is true, or Hawking would have his Nobel prize by now. Maybe consistent in the sense that the predictions are that Hawking radia…

> "Stephen Hawking used quantum mechanics to show that black holes emit radiation." I don't think this is true, or Hawking would have his Nobel prize by now Hawking not getting a Nobel by now doesn't mean much. Einstein never got one for relativity (either Special or General), and when he did get his Nobel he was told not to mention "relativity" in his speech.

Einstein, he was the guy who did all that great work in photoelectrics, wasn't he?

Re: Rethinking the origins of the universe

#113

Post by cruisername »

acjohnson55 wrote: post #86
lutusp wrote: post #71

Earlier quoted context omitted.

> even though the "Big Bang Theory" isn't generally believed any longer. Really? Given that science doesn't turn on belief but evidence, still, the Big Bang remains the best explanation for existing evidence. It's the prevailing cosmological theory of the universe' beginnings. Like all scientific theories, it's subject to replacement as new evidence appears and as new theories are crafted, but it's a good match at th…

I think it's a bit naive to say that science doesn't turn on belief. Scientist aren't robots, mechanically and dispassionately ingesting evidence and spitting out theory. They're humans with imaginations, beliefs, agendas, and egos, guided (hopefully) by a methodology that leads to discovery. I think belief is what drives science, and it's not all that bad of a thing.

Well, if your are willing to make a distinction between faith and believe, you might be right, IMHO, but that is opening a can of wormy questions that I'd better not go on writing about :)

Re: Rethinking the origins of the universe

#114

Post by cruisername »

lutusp wrote: post #95
acjohnson55 wrote: post #86

Earlier quoted context omitted.

I think it's a bit naive to say that science doesn't turn on belief. Scientist aren't robots, mechanically and dispassionately ingesting evidence and spitting out theory. They're humans with imaginations, beliefs, agendas, and egos, guided (hopefully) by a methodology that leads to discovery. I think belief is what drives science, and it's not all that bad of a thing.

> I think it's a bit naive to say that science doesn't turn on belief. That depends entirely on what we mean when we say "science". If by "science" we mean as defined and as practiced when it's done right, then no, belief plays no part -- it can't. If it did, it wouldn't be science. > Scientist aren't robots, mechanically and dispassionately ingesting evidence and spitting out theory. Scientists aren't robots, but th…

> [that it's naive to say that science doesn't turn on belief] depends entirely on what we mean when we say "science".

Or it depends on what we mean when we say believe. The weight lying on "science" does form a conceptual framework that completely ignores the notion of something beyond our reach, although it inarguably is the driving force behind science.

> In religion, something is true until evidence proves it false. In science, something is false until evidence proves it true -- exactly the opposite.

alright, but the word of god himself isn't evidence enough? j/k :)

> In religion, something is true until evidence proves it false. In science, something is false until evidence proves it true -- exactly the opposite.

Why do those have to opposite, can't they be reconciled into one, using some form of ternary logic? Edit: I mean, some things in life are unknown until proven true or false and then theres all kinds of methods to counter the fact.

Re: Rethinking the origins of the universe

#115

Post by TeMPOraL »

cruisername wrote: post #114
lutusp wrote: post #95

Earlier quoted context omitted.

> I think it's a bit naive to say that science doesn't turn on belief. That depends entirely on what we mean when we say "science". If by "science" we mean as defined and as practiced when it's done right, then no, belief plays no part -- it can't. If it did, it wouldn't be science. > Scientist aren't robots, mechanically and dispassionately ingesting evidence and spitting out theory. Scientists aren't robots, but th…

> [that it's naive to say that science doesn't turn on belief] depends entirely on what we mean when we say "science". Or it depends on what we mean when we say believe. The weight lying on "science" does form a conceptual framework that completely ignores the notion of something beyond our reach, although it inarguably is the driving force behind science. > In religion, something is true until evidence proves it fal…

> Why do those have to opposite, can't they be reconciled into one, using some form of ternary logic? Edit: I mean, some things in life are unknown until proven true or false and then theres all kinds of methods to counter the fact.

You reconcile them using Bayesian probability. There is no "proven to be true", there is no "proven to be false", there is only probability that flows between different models based on the evidence we discover.

"In science, something is false until evidence proves it true" actually means that any random hypothesis you come up with has an equivalent probability to be right to any other random hypothesis - which is infinitesimal, because possible hypothesis space is huge. Then, as evidence comes knocking, you update those probabilities, and some hypotheses become more probable (i.e. more likely a good models of reality), while other become too improbable to care about.

Re: Rethinking the origins of the universe

#116

Post by davesque »

lutusp wrote: post #72
davesque wrote: post #66

From the article: "Laura Mersini-Houghton has mathematically proven that quantum effects are strong enough to stop the formation of black holes..." If I'm not mistaken, Mersini-Houghton's work has just hit the scene. It still has to be vetted by the larger community before we could say that anything's been "proven."

Not to mention what I'm about to -- that scientific theories are never proven, only disproven. You can always tell when a journalist is speaking about a topic for which a scientist might be a better source. As to "mathematically proven", it's an unfortunate juxtaposition of math (where things really can be conclusively proven) and physics (where they cannot be).

Right. I was going to mention that as well, but didn't want to be too knit picky :).

Re: Rethinking the origins of the universe

#117

Post by lutusp »

cruisername wrote: post #114
lutusp wrote: post #95

Earlier quoted context omitted.

> I think it's a bit naive to say that science doesn't turn on belief. That depends entirely on what we mean when we say "science". If by "science" we mean as defined and as practiced when it's done right, then no, belief plays no part -- it can't. If it did, it wouldn't be science. > Scientist aren't robots, mechanically and dispassionately ingesting evidence and spitting out theory. Scientists aren't robots, but th…

> [that it's naive to say that science doesn't turn on belief] depends entirely on what we mean when we say "science". Or it depends on what we mean when we say believe. The weight lying on "science" does form a conceptual framework that completely ignores the notion of something beyond our reach, although it inarguably is the driving force behind science. > In religion, something is true until evidence proves it fal…

> The weight lying on "science" does form a conceptual framework that completely ignores the notion of something beyond our reach, although it inarguably is the driving force behind science.

Yes, but an idea doesn't become a matter of interest to science until it comes within our reach, in the sense of being observable in a way that forces different, similarly equipped observers to the same conclusion (the scientific meaning of "objective").

> Why do those have to opposite, can't they be reconciled into one, using some form of ternary logic?

Yes, an interesting question, but not really about science. Science concerns itself only with things that can be reduced to empirical observation, not belief.

> I mean, some things in life are unknown until proven true or false ...

That's true, but the basic scientific precept is the null hypothesis, the idea that things without evidence are assumed to be false. This is a great time-saver compared to granting credence to ideas without evidence, or assuming that something might be true until proven false (the unscientific outlook).

Re: Rethinking the origins of the universe

#118

Post by lutusp »

kijin wrote: post #108
lutusp wrote: post #98

Earlier quoted context omitted.

> The article implies that since singularities can't come into existence now, there can't have been a singularity at the moment of the Big Bang, either. Yes, that's true, but if the paper's thesis is correct, then there aren't any black holes or singularities at all, at any time. If the thesis is false, then there can be black holes at the universe's beginning, and they can form today, given the right conditions. > L…

No, the article only claims that a singularity cannot arise from a collapsing blob of matter. We have no evidence that the singularity that existed at the moment of the Big Bang was the result of a collapsing blob of matter. Therefore, we have no reason to think that it could not have occurred. In fact, it might not even make sense to think of that initial singularity as the result of anything at all, since causality…

> No, the article only claims that a singularity cannot arise from a collapsing blob of matter.

If true, it calls into question the existence of the initial singularity thought to precede the Big Bang. The alternative -- that the working of physical theories depends on circumstances -- isn't a very good one.

People sometimes hypothesize that this universe arose as a fluctuation in some other universe. For this kind of speculation to have any credibility, we have to assume that any singularity can be explained by physical theory, not just present-day singularities.

My point is that a theory whose workings depend on the circumstances isn't a very powerful one.

> We have no evidence that the singularity that existed at the moment of the Big Bang was the result of a collapsing blob of matter.

Look at this logically. If there was a singularity at the moment of the Big Bang, then it arose from the same physical theory that creates them in the present, but on a bigger scale. The alternative is to argue that physical theory is inconsistent, depending on circumstances. That sort of condition undermines physical theory, makes it more like a soap opera than science.

> In fact, it might not even make sense to think of that initial singularity as the result of anything at all, since causality requires time and there was no time before the Big Bang.

Yes, true, but once time exists, then we can start describing phenomena as having causes and effects. So physical theory only applies after time zero, not before. But if, at time zero, there was a singularity, we can try to apply physical theory to it. I'm not saying we will be successful, but it would be a mistake not to try.

Re: Rethinking the origins of the universe

#119

Post by wuliwong »

StefanKarpinski wrote: post #32

This paper claims that black holes can't come into existence, which is subtly different from claiming that they cannot exist. In particular, black holes can exist as long as they've always existed – it's just that new ones can't come into existence. Maybe the universe just has a fixed number of singularities. [I am not a physicist – this just struck me as an inaccurate implication in the article.]

I agree that it seems as if the article is a bit overzealous as to the implications of this work (claiming singularities cannot exist, in particular the one from which the big bang expanded). But, your idea that something has "always existed" in a universe that hasn't "always existed" doesn't seem plausible.

The author's claim that the big bang theory is now invalid because of this calculation of energy loss of a collapsing star being too fast to result in a black hole seems incorrect to me. The singularity from which the universe expanded (according to the big bang) is sort of "untouchable" by physics at the moment. I would guess there are some of the string/brane theory models out there that postulate what caused the big bang but currently it is my understanding that whatever information was around about the cause of that singularity is not accessible to us. Again, who knows what we will discover in the future but as of now, making any bold assertion about the lack of existence of that initial singularity seems presumptuous.

Re: Rethinking the origins of the universe

#120

Post by wuliwong »

AnimalMuppet wrote: post #9

If I understand correctly, black holes do not play a large role in our model of the origins of the universe. So this doesn't (directly) lead to "rethinking the origins of the universe". Does this work call the big bang into question (or even our current models of the big bang)? Or is it just details like galaxy formation that it makes us rethink? Another question: Something very massive and very small is at the cente…

Yes I agree with your first point. I think the author really oversteps their bounds. I don't see how this calculation speaks to the existence or lack of existence of a initial/primordial singularity.
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