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Everything posted by Genady
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Why is a fine-tuned universe a problem?
Genady replied to 34student's topic in Astronomy and Cosmology
I don't understand this. The question is not about "something", but specifically about our value of Lambda. Relatively small change in this value of Lambda would lead to a universe without planets, stars, galaxies, almost all chemical elements, etc, i.e. without life. -
Why is a fine-tuned universe a problem?
Genady replied to 34student's topic in Astronomy and Cosmology
If you imagine a probability distribution of different values of Lambda in various universes, then supposedly there are more universes with Lambda many orders of magnitude larger than what we got here. Or, there are more possible initial conditions that lead to the larger Lambda than the ones that lead to such a small Lambda. Each specific universe has the same probability to exist, but by picking a universe at random you get very small probability that it will have our value of Lambda. Vast majority of them will have a much larger value. -
Why is a fine-tuned universe a problem?
Genady replied to 34student's topic in Astronomy and Cosmology
I don't see, why it is not. I think so, too. And as I understand, Alan - and many other physicists - think so as well: it just happened so that this universe, either alone or one of many, can and does have life in it. I don't know where the impression of this being an issue came from. I mean, where in the science of physics. Philosophy is a different story, but that would be a different forum. -
The myth of invasive lionfish
Genady replied to Genady's topic in Evolution, Morphology and Exobiology
I read these stories and I think they are just reprints from 10 and 20 years ago. All the same claims, perhaps in the same words. No new evidence, one way or another. Why people and organizations do what they do? I can come up with numerous reasons. I am sure, you can too. The most innocent being, better safe than sorry. I think it is difficult to show that something has no effect. It is usually a null hypothesis. Anyway, after some 30 years and the wide range of invasion, where is the damage? It supposed to be big. I cannot find reports on that. -
Why is a fine-tuned universe a problem?
Genady replied to 34student's topic in Astronomy and Cosmology
How do you test this hypothesis? How do you test this hypothesis? How do you test this hypothesis? -
Why is a fine-tuned universe a problem?
Genady replied to 34student's topic in Astronomy and Cosmology
I've seen him interviewing Alan Guth. Guth said about the same that I've described regarding the vacuum energy density. Anyway, being interviewed doesn't mean that they "are submerged in this topic and they believe that there is a problem/issue that needs to be solved." Guth is not and does not. I don't know who is / does. Here it is: Alan Guth - What Does A Fine-Tuned Universe Mean? - YouTube -
Why is a fine-tuned universe a problem?
Genady replied to 34student's topic in Astronomy and Cosmology
Who are they? The only seriously considered related issue that I know of is the value of cosmological constant / vacuum energy density. And this is not because its fitness for life. Rather, the other way around: if we assume that this number can be different and that it actually is different in different "pocket universes", then the specific value that we observe is what it is simply because most other values don't allow for existence of an observer in those universes. -
The myth of invasive lionfish
Genady replied to Genady's topic in Evolution, Morphology and Exobiology
The old studies were small, short, and not convincing. This newer study is 5 years old, and it still only claims that the lionfish "pose a threat" and "can disrupt." It doesn't show that it actually does. It is an assumption of the study and a justification for it. Plus, it is a simulation, in one locality, and only regarding effects of harvest on the lionfish population (on the assumption that we want to reduce it). What does it show? It shows that if we harvest lionfish more, then their numbers will decrease (hardly unexpected). And, if we harvest native predators less, then the lionfish numbers will decrease. The latter in fact shows that there are native predators of lionfish! What I see on the grounds here, in Southern Caribbean is, no long term effect, no observable damage to the reef ecology. That's why I suggest it is a myth. -
Why is a fine-tuned universe a problem?
Genady replied to 34student's topic in Astronomy and Cosmology
The Newton constant of gravitation equals exactly 1 in Planck units, so it is not one of the numbers mentioned above. Scientists such as Alan Guth and Leonard Susskind are "serious scientists" in my book. Evidently, they don't know what you say here. How do you know this? 1. The existence or not existence of other universes does not depend on whether you call it scientific or nonscientific. 2. Anyway, how do you know that it cannot be refuted? -
Why is a fine-tuned universe a problem?
Genady replied to 34student's topic in Astronomy and Cosmology
A fine-tuned universe is not a problem, but an observation that the universe is very sensitive to a couple dozens of numbers that we put into our fundamental theories "by hand". These numbers are obtained experimentally or observationally. Relatively small changes in their values would lead to big changes in the observable universe. -
The myth of invasive lionfish
Genady replied to Genady's topic in Evolution, Morphology and Exobiology
OK. I only wish you would make it clear in that post. I cannot watch the video you've linked, but wanted to know what was your message. Have a good day. -
The myth of invasive lionfish
Genady replied to Genady's topic in Evolution, Morphology and Exobiology
Which argument are you attacking? -
The myth of invasive lionfish
Genady replied to Genady's topic in Evolution, Morphology and Exobiology
Would be helpful if the post comes with some explanation about what it is doing in the thread, so others don't need to check the link if they're not interested. I think, it is also a rule here. Anyway, is there anything about lionfish or invasive species in the video? What? -
The myth of invasive lionfish
Genady replied to Genady's topic in Evolution, Morphology and Exobiology
I don't know. Can you explain? -
The myth of invasive lionfish
Genady replied to Genady's topic in Evolution, Morphology and Exobiology
Wrong thread? -
Well, then this boson has to be massless in order to propagate with the speed of light as required by GR. And it was Richard Feynman I think that showed that such boson has to be spin-2 particle, based on GR again.
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Which "hypothetical graviton" did you refer to?
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The hypothetical graviton cannot be the Higgs boson because (a) the former should be massless while the latter is massive, (b) the former should be spin-2 particle while the latter is spin-0.
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The myth of invasive lionfish
Genady replied to Genady's topic in Evolution, Morphology and Exobiology
A slow dance with a quick ending. So much to the "Nothing eats lionfish" slogan. This video: -
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The myth of invasive lionfish
Genady replied to Genady's topic in Evolution, Morphology and Exobiology
Do the numbers work out? Population and population growth of the COTS on one hand, number of trained divers and their rate of injecting the COTS on the other? Will it make even a dent in the COTS population? Divers kill lionfish in this part of the world, but it doesn't make any difference in the lionfish numbers. It tastes good, though.