Activity for HDE 226868
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
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A: What would the real Miss Universe pageant be like? Sir? Mr? Ma'am? Miss? In a universe as large as ours (infinitely large, possibly) you're going to have a lot of species with more than two genders. So we can scrap the "Miss". I'm going to assume that there are two possibilities to solve this problem: Segregate by gender. Just make separate catego... (more) |
— | about 10 years ago |
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A: Emulating a geocentric planetary system TimB's answer is basically what I would write, except for a very small loophole that I'll include here. Any celestial body does not actually orbit another body, but a point in space called the system's barycenter, the center of mass. You can take a look at some of the animations here to get a good i... (more) |
— | about 10 years ago |
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A: How early was the Earth liveable for today's humans? I love this one. I really do. Quick Answer: I'd put the date at roughly 2.3 billion years ago, give or take. This is the date of the Great Oxygenation Event. It's when organisms (bacteria) began putting oxygen into the atmosphere in large quantities as a waste product of photosynthesis. The atmosph... (more) |
— | about 10 years ago |
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A: Earth Exploding This cannot happen. Here's why: Conservation of electric charge would be violated: The Earth is made of protons, neutrons, and electrons. Electrons are charge; protons and neutrons contain particles with charge. If you turned the Earth into a bunch of chargeless photons, all this would be gone. The... (more) |
— | about 10 years ago |
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A: Is this shattered planet scenario possible? Well, it's really, really, really, really unlikely, but I suppose there's a mechanism for it (albeit unlikely). I think you get the picture. Take your planet. Now take a very dense neutron star. Propel said neutron star through space at a high speed, and have it hit the planet. If the speed is high ... (more) |
— | about 10 years ago |
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A: Predicting lunar eclipses with multiple moons I realize that creating worlds with multiple moons and/or suns is risky I think I implied this is one of my answers. I suppose that this statement really comes down to opinion, but there's some rationale behind it. The point is this: Multiple stars can be risky; multiple moons generally aren't. ... (more) |
— | about 10 years ago |
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A: Does the sun being blocked affect electricity? Well, it might. But only a little, for now. As others have pointed out, we only get a small portion of our energy from solar power. However, the Sun is indirectly related to other methods of producing electricity: Wind power: The Sun heats air, which can produce currents that cause wind. We can ca... (more) |
— | about 10 years ago |
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A: Effects on the visual systems of humans when temporarily having several stars illuminating the living space TL,DR: TL,DR: Would humans beings from Earth be seriously injured or killed from the long period variation of the main color a bunch of stars projects on a planet? My TL;DR: Yes. Could such a scenario (referring to the planet being within the habitable zones of all three stars) exist? I'd think... (more) |
— | about 10 years ago |
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A: How close to interstellar space travel could humans get in the near future? Let's do a calculation or two, shall we? (Note: All those wishing to skip the boring math can just read the lower portion of this answer.) Finding the speed you're going for: $$v=\frac{15 \text { light-years}}{50 \text { years}} \times \frac{10,000,000,000,000,000 \text { meters}}{1 \text { light-ye... (more) |
— | about 10 years ago |
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A: Seasons on a planet that's tidally locked with the smaller star in a dual-star system Neil's completely right that the question is a bit confusing. There are two scenarios here: The planet orbits in the same plane as the stars, or it orbits 90 degrees perpendicular to them. There's a huge difference between the two setups. I have a feeling, though, that you're curious about the other,... (more) |
— | about 10 years ago |
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A: Would the knowledge of physics on a native aquatic planet be similar to our own? The hard part here would be that the medium this civilization lives in would be fairly disturbing. Ocean currents can fluctuate easily in certain spots, creating chaotic flows. Maelstroms and other disturbances would mess up the local environment, and rip currents could be devastating to creatures li... (more) |
— | about 10 years ago |
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A: What Factors Could Cause a World to See "Northern" Lights Much Closer to the Equator? One way to achieve this would be to simply change the structure of Earth's magnetic field. At the moment, the field is that of a large magnetic dipole, with the field produced by the motion of fluid within the core. Maxwell's equations (see Chapter 4 of these notes) tell us that this motion should pr... (more) |
— | about 10 years ago |
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A: How would an aquatic race develop computers? Awesome! I can talk about what I think is one of the coolest inventions of all time: the analog computer. An analog (more properly, a mechanical) computer was actually the world's first "computer" - the Antikythera Mechanism. It was an ancient Greek device that predicted the motions of the planets a... (more) |
— | about 10 years ago |
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A: What software can prototype a planetary system? My personal favorite is My Solar System, by the University of Colorado-Boulder. You can also access version 2.04 directly here. It's pretty basic, but it has some cool features. You can choose to view from the perspective of the system's center of mass, of that of a hypothetical stationary observer.... (more) |
— | about 10 years ago |
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A: Planet with dual core I don't know how realistic a scenario this is. I would think that if two cores formed in Earth (this could happen in the early solar system, if another moderately-sized protoplanet hit Earth), they would collide and merger, forming a slightly bigger core. For there to be two cores, they would have to... (more) |
— | about 10 years ago |
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A: Planet illuminated by blue-shifted relic radiation I'm not going to calculate at what speed the planet would have to move in order for this effect to happen. My guess is that it would have to go pretty darn fast for there to be a substantial difference, but I don't have much to back that up, other than (sometimes faulty) intuition. Could a planet be... (more) |
— | about 10 years ago |
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A: How would solar activity change if the Sun was impacted by a planet? Mercury vs. the Sun Mass: Mercury - $3.3022×10^{23} \text{ kg}$; Sun - $1.98855×10^{30} \text{ kg}$. Mercury clearly won't so much as jostle the Sun. There should be no major changes in the Sun's orbit around the galactic center. Composition: Mercury - oxygen, sodium, hydrogen, and iron; Sun - hy... (more) |
— | about 10 years ago |
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A: If a space ship crashes on a planet, is it realistic that things from that space ship could be rescued afterwards? I think another defining factor is how large the ship is to begin with. If you have more components (more engines, wings (for a spaceplane), landing gear, etc.), there's a greater chance that something will be damaged, but a smaller chance that everything will be damaged. If you take 10 engines and s... (more) |
— | about 10 years ago |
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A: How close must a supernova be to severely harm the Earth? Awesome question. I love this kind of thing. Wikipedia of course has a a page on near-Earth supernovae, and the first body paragraph briefly examines the effects of life on Earth. The only really important thing there is just what you said - that the gamma rays from a supernova could deplete the ozo... (more) |
— | about 10 years ago |
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A: Could Mars-colonized humans survive a return to Earth? You could always simply lie down. Jokes aside, the answer is that there would be quite a few issues. Your spine would not be used to being so compressed. This is a problem with astronauts returning home from extended stays in space. There are two key issues: Spaceflight osteopenia: In microgravity... (more) |
— | about 10 years ago |
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A: How do I get rid of the Earth or local Solar System? A few easy steps to destroying Earth: Get hold of a fairly massive celestial body. It could be a star, a rogue planet (as PipperChip mentioned), or something completely different. Put it in a position so that it is orbiting the galaxy at the same rate the solar system does - except much higher up o... (more) |
— | about 10 years ago |
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A: Gravitational effects of portals at different heights This is a really cool question, and I think I can (partially) answer it. Here goes. If two portals are placed a different heights, someone approaching the higher portal should perceive a gravitational pull towards the portal, right? I'll assume that you're talking about an object in between the... (more) |
— | about 10 years ago |
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A: Different gravitational and inertial mass As has been discussed already, different objects would fall at different speeds. Why? Wikipedia led me to an interesting derivation. Consider Newton's second law: $$F=mia$$ Now consider his law of universal gravitation: $$F=G\frac{m{g1}m{g2}}{r^2}$$ Now, because the force here is due to gravity, we ... (more) |
— | about 10 years ago |
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A: Could a cold planet (tundra) develop and maintain a breathable atmosphere for humans? I'm going to give you a cautious "yes". The reason I'm being cautious is that it depends partly on a hypothesis that is, and has always been, controversial. If it's correct, then absolutely, this scenario is possible. If it's wrong . . . well, perhaps the following reasoning is incorrect. Have you e... (more) |
— | about 10 years ago |
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A: Precision Destruction by a Cosmic Being (Or how to destroy StackExchange from space) Secure $850 quadrillion, preferably in cash. Figure out a way to get around one or two famous and fairly successful treaties. Build a Death Star. Modify the Death Star so it won't blow up the entire planet, but instead will concentrate a fair amount of energy into a single spot. Wait for each office... (more) |
— | about 10 years ago |
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A: How could a specific asteroid be diverted to impact the earth? Here's a quick guide to changing the orbit of an asteroid: Figure out where it is. This is the crucial bit. You need to know its position, mass, velocity, orbit, size, density, and composition, and perhaps one or two other parameters. These are crucial, especially the first three. You'll need all t... (more) |
— | about 10 years ago |
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A: What would the weather be like in an asteroid habitat? Here on Earth, the majority of weather-related events happen in a layer of the atmosphere known as the troposphere. It lies from Earth's surface to approximately $20 \text { km}$ - at its highest. Asteroids can range in size from a few meters to $1,000 \text{ km}$, so it's quite likely that we could ... (more) |
— | about 10 years ago |
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A: A realistic road network Assuming you have a map, I would first plot out all the different settlements. Towns, cities, villages, hamlets, outhouses - everything. Now connect them in straight lines. Completely straight. It doesn't matter if the lines go over an ocean or through a volcano; we'll modify them later. The point of... (more) |
— | about 10 years ago |
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A: What would be the effects of the common house cat rapidly acquiring flight ability? I suspect that they would lose any flying ability rather quickly. Here's why: If you own a cat, you probably have an emotional attachment to it. Perhaps that's a strong attachment. You'd be pretty upset if your cat left, right? (I think I can safely say that's the case based on all the desperate "Lo... (more) |
— | about 10 years ago |
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A: Could knowing the state of the universe at time T allow to predict the state T+1? Yes and No Quantum mechanics is full of probability. You simply can't get around it. You can never know for sure if a particle at time $t$ in the future will be at point $A$ or point $B$. Quantum mechanics forbids it. Sure, the odds could be essentially 100-to-1 against that it will be at point $B$,... (more) |
— | about 10 years ago |
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A: If our universe was a simulation, what could a bug look like? If a universe is a simulation, then, logically, it must have all the natural laws built into it. Agreed? Now, if it is a deterministic universe - that is a universe where, theoretically, you could predict its entire future if you knew everything about it at a certain point in time - these laws would ... (more) |
— | about 10 years ago |
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A: Impacts of a stellar Jupiter Physical properties If Jupiter turns into a star, it would likely turn into the least massive star possible. This would make it a red dwarf - in particular, a red dwarf of spectral type M9V. We can infer a few key properties from this: Mass: $0.79M{\odot}$ ($82.8MJ$) Luminosity: $2.69\times10^{-4}... (more) |
— | about 10 years ago |
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A: What would the Universe be like if gravity was slightly stronger? Not a lot would be different, actually. Let's take the orbits of the planets around the Sun. In the Newtonian world, gravity is represented by Newton's law of universal gravitation: $$F=G\frac{m1m2}{r^2}$$ where $F$ is force, $G$ is the universal gravitational constant, $m1$ and $m2$ are the masses ... (more) |
— | about 10 years ago |
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A: Life on a planet with multiple gas layers A planet could definitely have multiple gas layers. As was discussed here, gravity affects different gases differently, based on their mass. In other words, there would be more force between the Earth and an $\text{O}2$ molecule than there would be between the Earth and an $\text{H}2$ molecule. It's ... (more) |
— | about 10 years ago |
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A: Asteroid impact. How big does it have to be to globally affect plate tectonics? I think we've established that this monstrous object is going to have to be pretty darn big. You suggested that it could be 500 kilometers in diameter; let's do the calculations to figure out just what the effects would be. From Wikipedia, the median velocity of an oncoming object hitting Earth is a... (more) |
— | about 10 years ago |
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A: What would have to happen in order to force us to live in the ocean? The first thing that comes to mind is an incredibly large volcanic eruption. And I mean a huge eruption. Something never before seen on Earth. One of the largest (if not the largest) eruptions we know to have happened was that of the Toba supervolcano. It released a staggering 2,800 cubic kilometers ... (more) |
— | about 10 years ago |
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A: Cluster of Black Holes around a Central Point Under the circumstances you describe, my immediate reaction is that it would not be possible. The issue here is that the cluster would be fairly unstable. The black holes would all be mutually attracted to each other, and would soon coalesce into one large black hole - taking the Imperial research ce... (more) |
— | about 10 years ago |
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A: Living Planet Possible? Let's say you have a planet pretty similar to Earth. It resembles Earth at around the time life is thought to have begun - except that it's a bit less hostile to life. The atmosphere is mainly carbon dioxide and nitrogen, the oceans have plenty of water, and the tectonic plates are relatively stable.... (more) |
— | about 10 years ago |
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A: Where in the solar system is the most viable place to put my colonists, after Mars and Luna? My choices: Ganymede and Callisto (and maybe Titan) This is perhaps a bit of a buzzkill, but I honestly would not recommend colonizing much in the solar system besides the Moon and Mars. Here's why I would take a lot of bodies off the table: Mercury - Too hot on its sunny side for colonization (up... (more) |
— | about 10 years ago |
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A: Terraforming a gas giant into an habitable planet This is really sort of cheating, but it could actually work, so here it goes. As professorfish says, It is theoretically possible, but I don't know how you could rip off the atmosphere and mantle. Very true. Jupiter's atmosphere is about 5,000 km high, and comprises the majority of the planet'... (more) |
— | about 10 years ago |
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A: What if time travel had to take into account spatial distance? As Neil pointed out, there is no absolute frame of reference, so I'll pretend that the frame of reference is relative to something - in some scenarios, the Sun; in others, the Earth, and in others, the center of the Milky Way. What potential for abuse does this situation have? Well, there's alw... (more) |
— | about 10 years ago |
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A: Could underwater living organism create technology? I'm actually going to answer the question from the opposite viewpoint of TimB, if only because there are some loopholes to a lack of fire. They primarily apply to deep-sea civilizations, but still, they're moderately feasible. Heat Heat would be a very big problem for an underwater civilization. Th... (more) |
— | about 10 years ago |
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A: How would a planetary nebula affect a planet? TL;DR To make a long story short, the planet will lose its atmosphere and some of its crust, but most of it will remain intact, even in the worst-case scenario. That should be the major effect you'd have to deal with. Nebula properties Let's review some key characteristics of planetary nebulae: ... (more) |
— | about 10 years ago |
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A: How big could a living thing be? This is only a partial answer (it only addresses land animals), but I don't know if anyone else is going to mention it, so I might as well. Land animals rely on their bodies to support their weight. A lot of that support comes from their bones. Now, a bigger animal will have bigger bones, so the vol... (more) |
— | about 10 years ago |
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A: Can an atmosphere englobe a planetary ring? I'll take a completely different approach from what everyone else is saying, because everyone (okay, sans ivylynx) seems to be assuming that there are asteroids in planetary rings. This is not true. The objects that make up a planet's rings can come in a range of sizes, but none are as big as an aste... (more) |
— | about 10 years ago |
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A: What would be the effect on life/civilisations if the length of a year was longer or shorter? I'm actually going to consider how such a year would affect animals, because I have a feeling nobody else is planning on addressing it. This should be short and to the point, unlike some of my other answers. Many animals have a "mating season" - i.e. a period each year where they mate. This can mani... (more) |
— | about 10 years ago |
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A: What kind of star should I use for my world? I'll narrow down your list by talking about all the stars you shouldn't use. You'll find it gives you a pretty narrow range. Let's start with the exciting ones: neutron stars. These are, technically, stellar remnants, leftovers of massive stars that blew themselves apart in supernovae. Supernovae ar... (more) |
— | about 10 years ago |
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A: Would a civilization that is trying to colonize a landless world be able to do so? Actually, some of the challenges you describe might not be too hard to overcome. Maybe you've thought of the same things I have. Metals I'll tackle smelting first. The key issue you described is that fire would be impossible to create. Well, there is a workaround. Smelting doesn't necessarily need ... (more) |
— | about 10 years ago |
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A: How could a force field dome be realized in my city? Here you can use an actual physical field to act as a force field - in certain scenarios. Let's say you want to stop a single particle. What can you do? You can trap it. Not deflect it, in the sense you mean, but make it get stuck in a single point in space. Here's how: If the particle has electric ... (more) |
— | about 10 years ago |
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A: Feasibility of anti-matter as a fuel I'll address storage of antimatter, because that is the one thing in your question humans have done successfully so far. While we may someday build an antimatter-based propulsion device, it's a ways off. Storing antimatter is another story. Currently, the best way to store antimatter is a Penning tr... (more) |
— | about 10 years ago |