Starts With A Bang

Amazing discovery! On a related note, it's possible to have rogue solar systems as well: https://medium.com/starts-with-a-bang/ask-ethan-can-stars-escape-from-…

AskEthan did a great write up about this exact scenario and if planets could escape along with the star: https://medium.com/starts-with-a-bang/ask-ethan-can-stars-escape-from-…

Still: https://medium.com/starts-with-a-bang/only-dark-matter-and-not-modifie… "Modified gravity cannot successfully predict the large-scale structure of the Universe the way that a Universe full of dark matter can. Period. And until it can, it’s not worth paying any mind to as a serious competitor. You cannot ignore physical cosmology in your attempts to decipher the cosmos, and the predictions of large-scale structure, the microwave background, the light elements, and the bending of starlight are some of the most basic and important predictions that come out of physical cosmology. "

> There have been a longstanding problem that the history of the universe and cosmological distance scale haven't made sense. https://medium.com/starts-with-a-bang/the-hubble-tension-sti... > When I was getting my PhD in condensed matter physics I was going to the department colloquium all the time and seeing astrophysics talks about how some people thought the hubble constant was 40 km/s/Mpc and others thought it was 80 km/s/Mpc. With timescape cosmology maybe they were both right. You're (mis)remembering a different (old) problem and confusing it with a new one. The problem in the 1970s and 1980s was: what is the local expansion rate of the universe? Where "local" mean "within a few hundred megaparsecs". There were two main groups working on the problem: one group tended to find values of around 50 km/s/Mpc and other values of around 100. Gradually they began to converge (in the early 1990s, the low-H0 group getting values of around 60, the high-H0 group values of around 80), until a consensus emerged that it was in the low 70s, which is where we are now. The "Hubble tension" is a disagreement between what we measure locally (i.e., a value in the low 70s) and what theory (e.g., LCDM) says we should measure locally, if you extrapolate the best-fitting cosmological models -- based on cosmological observations of the CMB, etc. -- down to now (a value in the upper 60s). This has only become a problem very recently, because the error bars on the local measurement and the…

>"Calcium copper titanate (also abbreviated CCTO, for calcium copper titanium oxide) is an inorganic compound with the formula CaCu3Ti4O12. It is noteworthy for its extremely large dielectric constant (effective relative permittivity) of in excess of 10,000 at room temperature.[1]" Also: https://medium.com/starts-with-a-bang/the-last-barrier-to-ultra-miniat… >"The photograph shows the large grains of a practical energy-storage material, calcium-copper-titanate (CCTO), which is one of the world’s most efficient and practical ‘supercapacitors.’ The density of the CCTO ceramic is 94 percent of the maximum theoretical density." Here's a wierd idea: When we think about capacitors -- we think about the ability (of a material) to hold an electrical charge. But, what if it's not an electrical charge that the material is actually holding? What if what the material is really holding -- is the deformation of space (compression, expansion, twisting, rarefaction, pressure, ?) Or, what if the material was really holding -- was some kind of vibration or vibrations, just we can't detect them with our instruments just yet? Or maybe both of the above, just that what it is, depends on how we look at it, what we measure, how we measure it... Then, that in turn brings up the electrical field. In theory, all capacitors should have some kind of electric field surrounding them. In other words, let's suppose you had…

> Space expands everywhere, also right in front of you, it is just a very small effect over short distances ... .07 nanometers per year but two points one kilometer apart move away with 70 nanometers per year because there are a thousand meters in between them No, what you wrote is contradicted by evidence from within the inner solar system (MESSENGER's observations of solar mass loss were highly sensitive; we have excellent VLBI too), from other star systems, especially eclipsing binaries and systems with occluding planetary systems) and from galactic dynamics (LSR tests, peculiar motions, and lots of DM/dynamics evidence for galaxies at different redshifts). It is not how the standard model of cosmology works either. Grossly, 0.07 nanometers per metre per year expansion everywhere would be impossible to hide from solid state physics, and even several everyday polymers and ceramics; an expansion term would have to appear in accurate descriptions. We cannot say there is no expansion at these scales, but the expansion is highly constrained and evidence requires that it effectively vanishes. A fifth-force mechanism like quintessence requires a shutdown mechanism inside galaxies that contain star systems like ours or TRAPPIST-1 or PSR~J0337+1715. Additionally it likely would need a shutdown in small structures (like asteroids) ejected from galaxy clusters by violent events, although we will not spot those in practice any time soon. Where there's a shutdown mechanism…

>Although "Quantum Teleportation" could that theoretically be used to "teleport" a spacecraft FTL? Everything I've ever read about quantum teleportation says no [0..2]. Even if state changes are instantaneous, the transmission of information itself is still limited to the speed of light (and a ship counts as "information" in this case), and the process of quantum teleportation would require some classical communication channel to transmit state. All that notwithstanding the amount of energy you would need to "entangle" an entire ship in the first place. [0]https://www.quora.com/Is-the-any-possibility-that-Quantum-Teleportatio… [1]https://medium.com/starts-with-a-bang/ask-ethan-can-we-use-quantum-ent… [2]http://www.askamathematician.com/2013/01/q-what-is-quantum-teleportati…

sigh I wouldn't have replied to this if you hadn't posted half a dozen comments. When I was 16 I thought special relativity was a hoax and I tried to demonstrate this with triangular diagrams scribbled in pencil in my notebooks. I ended up just rediscovering the Doppler effect. I never showed it to anyone, but when I think back, I still cringe a little. Relativity and time dilation are real things with real theory and real experiments. You'd do well to do a little more research on the topic before posting so many comments on HN. There is a ton of evidence for dark matter. We still don't know exactly what it is, but we do know lots about it (e.g. it is not baryonic matter because observation differs from theoretical models of how it would interact with ordinary baryonic matter). As for all that other evidence, the first hit on Google is for laymen: https://medium.com/starts-with-a-bang/five-reasons-we-think-dark-matte… TLDR: gravitational lensing, missing mass, and three other really good reasons that dark matter is a serious subject of study. Disclaimer: I am not a physicist. And I'm trying not to represent myself as one on HN. Talking about this stuff is fun, sure. It's great to learn! But please don't spread ignorance with such high confidence. As for "just" Newtonian physics, there's a whole research field called "Modified Newtonian Dynamics" (MOND). https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics TLDR; there are lots of problems with…

This is from August 3, 2023, so 1.5 months old: has it caused a bigger stir in astrophysics since then? I'd have expected it to be all over the popsci web (Quanta, Aeon, etc). So I gotta wonder whether it caught on. I think this is the preprint: https://arxiv.org/abs/2207.11069 Added: per Ethan Siegel's mMdium post (clickbait link to incomplete article): https://medium.com/starts-with-a-bang/ask-ethan-do-binary-stars-prove-… "The quick answer is that this result is a confluence of three things: good science, bad science, and the ugly state of science news. Let’s look at what’s truly going on here." Archived snapshot of full article: https://archive.ph/Vxudc

Indeed, I didn’t expect to learn some physics in Fortune. Hm, he has a blog [0], but it’s on Medium. [0] https://medium.com/starts-with-a-bang

This is a good write-up that justifies dark matter using 7 independent pieces of evidence: https://medium.com/starts-with-a-bang/7-independent-pieces-of-evidence…

God opened Vim and set 26 constants https://medium.com/starts-with-a-bang/how-many-fundamental-constants-d…

Well, in this case they're not just inventing nonsense to fix one little thing. There are a lot of various pieces of evidence, all pointing to this fix. If you want to patch up a lot of little pieces of evidence, each with it's own magic, that would be even more "un-parsimonious". The evidence for dark matter is pretty solid. As this [1] article states, while giving 5 independent reasons scientists think dark matter exists, "No other idea explains even two of these". Wikipedia lists eleven different places it shows up. The research literature has more. And AFAIK there is no other unified (or even close to unified) explanation for all these observational pieces of evidence. [1] https://medium.com/starts-with-a-bang/five-reasons-we-think-dark-matte… [2] https://en.wikipedia.org/wiki/Dark_matter

Here's a link about this idea by Ethan Siegel, and its HN discussion thread (thanks 'petilon for helping me remember the author): https://medium.com/starts-with-a-bang/the-disappearing-universe-d74474… ("The Disappearing Universe") https://news.ycombinator.com/item?id=7896776 (64 comments)

Schrodinger of Wave Equation fame said he regretted ever having anything to do with QM, for example. Here's a good short write-up: https://medium.com/starts-with-a-bang/einstein-schr%C3%B6dinger-and-th…

It's not the existence of these phenomena that's unexplained, but specific observations that don't fit our current theories. This article seems like a decent introduction: https://medium.com/starts-with-a-bang/five-reasons-we-think-dark-matte…

No, there are other reasons[1] we believe dark matter exists, it's not just a fudge factor in the math. There are multiple lines of evidence pointing at its existence. [1] https://medium.com/starts-with-a-bang/five-reasons-we-think-dark-matte…

This is one of the explanations: https://medium.com/starts-with-a-bang/ask-ethan-if-dark-matter-is-ever…

You're getting down voted for a fair assumption, and no explanation. We can see more distance than the age of the universe Because Expansion of the universe Here is a complete explanation https://medium.com/starts-with-a-bang/how-is-the-universe-bigger-than-…

I needed some more details of how the photon experiences time, and found this (first good google result). But useful. https://medium.com/starts-with-a-bang/ask-ethan-109-how-do-photons-exp…

Ethan Siegal's articles are usually re-published on Medium a few days later: https://medium.com/starts-with-a-bang

> Why is Forbes writing about it now? Why not? Look who the author is: Ethan Siegel. He has a blog (https://medium.com/starts-with-a-bang) and a podcast (https://soundcloud.com/ethan-siegel-172073460). He basically does a Dear Abby type column based on astronomy and physics topics. He takes difficult concepts and tries to break them down into something the lay person can understand. Quite frankly, I think he's pretty damn good at it and we should be happy Forbes is publishing his stuff for a wider audience.

Long story short, no and that's because forces are only applicable in certain situations and not others, and in this case gravity, electromagnetism, and similar subatomic forces are binding the atoms we know and preventing them from "expanding". I'm not an expert and this is just my simplified version of a simplified version. Here's more to read about it: https://www.quora.com/Astrophysics-If-the-universe-is-expanding-why-ar… https://medium.com/starts-with-a-bang/ask-ethan-if-the-universe-is-exp…

I find the argument that advanced growing alien civilizations would construct "Dyson Swarms" pretty convincing. These structures have the huge advantage that no new physics is required- we could start building ours now with today's technology. They would look like infrared point sources. Sadly none detected yet: https://medium.com/starts-with-a-bang/dyson-spheres-the-ultimate-alien…

You are right. Based on an image in this article [1], the EELT would be the largest optical telescope, once completed in 2022, two years after the GMT, if the dates are correct. And in the battle for superlatives, the cancelled OLT would have been the largest of them all. [1] https://medium.com/starts-with-a-bang/worlds-largest-telescope-will-re…

Earth being 'in the way' causing fewer meteor strikes doesnt account for the differences between the near and far sides of the moon [1]. It's a fairly small effect apparently. Of course, any moon base would probably be on the near side anyways to communicate with earth. [1] https://medium.com/starts-with-a-bang/the-two-faces-of-the-moon-398fbc…

> undetectable-through-normal-means normal matter I assume by this you mean dust and planets and such. https://medium.com/starts-with-a-bang/could-dark-matter-just-be-normal… That also goes for 'aliens', because presumably, they'd also be made of normal matter, and if they're not, then we're back to some exotic form of matter like dark matter. As far as being a mistake, it could be possible that we are fundamentally misunderstanding something about how gravity works. That would be as interesting a result as dark matter, to be honest.

> The density needed to form a black hole decreases linearly with radius, sho why is the universe not one? I feel like this explains it pretty well. https://medium.com/starts-with-a-bang/ask-ethan-50-why-didnt-the-unive… tl;dr: Schwarzschild’s solution is a static one, meaning that the metric of space does not evolve as time progresses.

https://medium.com/starts-with-a-bang/five-reasons-we-think-dark-matte… While I'm not an astronomer, I think observations such as the the Bullet Cluster and the different position s for where the mass seems to be - including big changes in morphology, not just location - clearly indicates that something dark matter/energy-like must exist. The precise nature of this DM/DE is an a separate question.