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Everything posted by MigL
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Yeah, that happens to us 'old folk'.
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This is what happens when you build a 'model' based on an incorrect premise. Once that incorrect premise is pointed out, the whole model collapses like a house of cards. The Universe is not expanding away from a center, rather, the separation between galaxies/clusters is increasing. AND, the expansion rate is the same throughout the universe. The density of matter/energy is not less at large separations, but actually greater, since looking into distance is equivalent to looking back in time, so we 'see' the universe at an earlier, denser stage. Ask questions before building elaborate ideas on your misconceptions; people here will be more than happy to answer.
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That would include everything before the IBM PC ( and even some later computers ). The original Mac did not use DMA, and even computers like the Commodore 64/Amiga used DMA only for graphics manipulation ( Sprite engines ) as the Motorola 68000 CPU was rather expensive in combination with its DMA controller, while the Intel 8088CPU/8237DMA combination in the IBM PC was relatively cheap. My first two computers, a Sinclair ZX-81, and a Xerox 820 bare board ( to which I soldered components ), both used Zilog Z-80 processors and interrupt driven I/O.
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You need to specify the scope of this 'full' computer system, for anyone to be able to tell you what components you need. A full computer can be as simple as a SoC ( system on a chip ), with ROM, DRAM, and I/O interface chips. This is similar to Raspberry Pi, Arduino and most phones and tablets. Most home computers are not as integrated, and usually have busses ( such as PCI-E, for expansion, sound controller/generator, SATA controller, keyboard/USB controller, etc. Video can be integrated in the CPU or not ( in which case you'd need a video card ) but the memory controller is usually integrated these days. And of course, you still need ROM, DRAM and I/O interface chips ( for voltage levels ). Then again you could build a computer the old fashioned way, with discrete logic chips. I am only familiar with the 74LS series ( low power Shottky ) which were popular during the late 70s and 80s, but you could even build your own CPU with discrete logic. And in a related fashion, the new supercomputers are made using massively paralleled video cards ( which are themselves large numbers of paralleled simple CPUs ), all hung on the same Buss. I assume the simplest option, using an SoC, you mentioned that you've already explored. You need to specify the complexity ( and the use ) of this 'full' computer
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Extraterrestial life searching
MigL replied to Stormloop's topic in Evolution, Morphology and Exobiology
I'm not sure about the floating part, but there are other substances that expand when frozen solid. Silicon and Gallium ( used in semiconductors ) come to mind, but I'm sure there are others. Has to do with the way molecules aggregate into the solid crystal structure taking up more space than freely moving molecules. It is fortunate that ice floats for Earth based life, meaning seas and oceans don't freeze from the bottom up, and aquatic life is possible. But this wouldn't be necessary on a planet where the temperature doesn't drop below 00 , or where the prevailing liquid has a wide temperature range liquid state. We are limiting our criteria of life, to life 'as we know it'. But there are certainly arguments for life based on other chemistries. Carbon based life is suited to temperatures where water is liquid, but at much higher temperatures sulfur based or even silicon based life might be possible ( sulfur and silicon don't form as many compounds as carbon, but they are prolific in their bonding ). -
how much of the outer universe can we see from where we are?
MigL replied to boo's topic in Astronomy and Cosmology
Yeah, 200 mill, not 200 thou. Yeah, as I said I thought the same thing, however, we are located near the Orion arm of the galaxy, about 30 000 LY from the galactic center, and about 20 000 LY from the edge of the galactic disk. And there s enough gas, dust and stars between us and the edge to block most of our view. The zone of avoidance s a band that encircles us. -
how much of the outer universe can we see from where we are?
MigL replied to boo's topic in Astronomy and Cosmology
I would have thought that to be true when viewing through the center of the galactic disk. But I would have thought that, when viewing towards the outer rim of the disk, infrared and microwaves would easily get through, even as most visible wavelengths would be appreciably attenuated by gas/dust and a lot fewer stars. edit And I guess I thought wrong. Although I do see mention of that effect in your link, Janus. -
Since when do you need a source for an opinion ? Then why not ask what non-IGNORANT, enlightened people prefer ? And in what way do you mean 'better' ?
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Almost anything painted matte black will heat up faster than if left with a shiny/colored surface. Black will absorb more of the incident radiation, while shiny or colored will reflect some. However, copper is also very conductive, which means heat will be carried away to all exterior surfaces quickly, and re-radiate. There is also the matter of the paint/copper interface, and how conductive it is. ( IIRC, copper needs a zinc based primer for paint adhesion, which further complicates matters ) So you asked a very vague question, to which no one can give an exact answer. I suggest redefining the parameters of your question, or simply trying the experiment with those you have in mind. Also keep in mind that the intended use comes into play; is it for heat storage, or removal ?
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I Thought Islam had brought the old knowledge of the Greeks, and the scientific method of inquiry, back to Catholic Europe, to end the so called 'dark' ages, and usher in the Renaissance and the 'age of discovery'.
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I did not personally know anybody who had tested positive until the beginning of October. The son ( in his middle 20s, and his girlfriend ), of a good friend of mine. His mother lives in the US, and he may have visited her. My friend, who had been in contact with his son, had to isolate from his second wife also, as she has an elderly, sick mother. We don't have many cases n the Niagara region of Ontario, but who knows how many asymptomatic people I may have come in contact with. Don't be a Trump; wear a mask, wash your hands, and, if possible, keep separated.
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That would make for an interesting design exercise. The speed of sound in water is approx. 1500 m/s. Streamlining ( finesse ratio )would need to be extreme ( long and pointy ) so the shock wave would disturb a very thin cone of water. And Whitcomb area rule where any control surfaces are located. Propulsion would be another problem; the standard axial screw ( propeller ) could not be used as the thrust would need to be faster than supersonic ( no such thing as a supersonic propeller plane ). The only viable solution would be rocket propulsion. A 'trick' used by Russian torpedoes is to encase the hull n a sheath of gas ( usually Oxygen generated by H2O2 ) to enable faster speeds; that might also be applied. This however, would negate the benefit of the water as a heat sink to alleviate dynamic heating. Does anyone think anything of the sort would be feasible ?
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Thank goodness Moon. I thought the age of Aquarius died with the coming of Disco in the middle 70s. So free love, and mind expanding drugs are still OK ? ( joking, I haden't even reached puberty yet in the early 70s )
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I would like to see your paintings; paranormal research ( ghostbuster ? ), I can do without. The rest is gibberish, and playing with numbers. A 'model' is supposed to allow you to make predictions, and let you to check those predictions against observations. And while we don't have 'observations' of the tunneling effect producing Hawking Radiation, we base our best ( and accepted ) guesses on known Physics. ( entropy, thermodynamics and quantum mechanics ) Hence, known as 'educated' guesses; everything else is WAG.
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So, what does this mean ? My electric drill no longer works ? People are 'delusional' when they argue against reality. ( not to worry, there's medication for that )
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Well, for one, the Bible says "treat others as you would have them treat you". Isn't salvation in the afterlife ( heaven ) enough incentive ? No really, the realization that if everyone does it, everyone benefits ?
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That's right. The Northrop F-20 Tigershark, a development of the F-5 and T-38, was involved in two crashes during development/sales tours, which were effectively caused by aggressive maneuvering ( sustained 9g ). This caused the pilots, Cornell and Barnes, to gradually lose peripheral vision until blackout; neither of themsurvived the crashes. Cornell died during a demonstration in Taiwan. Barnes died practicing an air show routine here in Canada. https://nationalinterest.org/blog/buzz/video-alert-watch-unfortunate-f-20-tigershark-first-prototype-crash-68937 https://www.latimes.com/archives/la-xpm-1985-05-15-mn-8541-story.html
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No, but how you come to a stop might. ( falling off a building never killed anyone; it's that darned landing that does )
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I would think if everyone treated everybody else, regardless of religion, a little more politely, quite a bit more progress would be made. Szczęść Boże
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The fact that a re-entry vehicle is trying to slow down, and so presents a 'blunt' face to the atmosphere, is where most of the heating comes from. A 'streamlined' re-entry vehicle would hit the ground at thousands of miles per hour; the space shuttle re-enters bottom first to generate 'slow-down' drag, and the reason ablative tiles are attached to bottom surfaces.
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Hope every American on this forum ( even ones who don't participate ) who hasn't already mailed in their vote, masks up ( along with any other PPE you can get your hands on ), and gets out to vote on Nov 3. Just ask yourself whose vision of America you would like to see as outlined in the debate; D Trump's 'everything for the economy', or J Biden's 'compassionate, fair, and respected worldwide' ? ( although even D Trump's 'vision' is a fabrication which he'll never deliver )
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if there was a rogue black hole hurtling towards us would we know?
MigL replied to boo's topic in Astronomy and Cosmology
Stellar size BHs ( from collapsed former stars ) tend to follow orbits around the galaxy, just like stars do. We have an equivalent chance of colliding with another star as we do with a stellar BH. Galactic core sized ( millions or even billion solar mass ) BHs are another matter. Although just about every galaxy has one ( or more ), to be ejected and become 'rogue', they need to be involved in a collision. Just how many galactic collisions are there ( or were ) within 100 million light years ? Not very many at all. Chance of one reaching our galaxy within a billion years, virtually nil. Although in about 4.5 billion years Andromeda will collide with the Milky Way, chances of stellar or BH collisions are very low. ( interstellar pace is HUUUUGE compared to the size of stars ) -
Aliens on 1,000 nearby stars could see us, new study suggests
MigL replied to Curious layman's topic in Science News
The Sun is a magnitude 5.8 star, barely visible from 50 LY distance. However, about 100 years ago, we started broadcasting information embedded in EM carrier waves out into the universe. Any advanced civilization residing on one of the 133 star systems within 50 LY, would have detected us 50 years ago, and their armada, travelling here at light speed should be passing the outer gas giants as we speak. Yeah, I'm joking ( maybe ). -
A good scientist doesn't believe anything, literally. However, even someone like Studiot will occasionally substitute 'have good evidence for' with 'believe". That's the human part.
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I don't see how you get that from Studiot's comment. GR assigns a 'curvature to space-time at the exact location of the electron's mass/energy/momentum. But QM says the electron doesn't have an exact location. Now do you see the problem ?