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Janus

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Everything posted by Janus

  1. From your image: Depth of the hole would be the difference in gravitational potential. The " steepness" at any point is local gravitational strength. So, from this diagram, local gravity would be zero both inside and outside of the "hole". The walls (if straight up and down) would represent infinite gravitational strength over zero distance. (Not a realistic scenario) The edges between the walls and the flat areas would have an infinite tidal force. Since gravitational time dilation is related to difference in gravitational potential and not a difference in gravitational strength, Time would run slower at the "floor" of the hole by an amount determined by by the depth of the hole.
  2. That idea fails on many levels. For one, for diamagnetism to exert a "force", there has to a variation in field strength. Diamagnetic materials will tend to move towards the weaker part of the field. So for it to even work to explain dark matter, you would need the field strength to be greater outside of the galaxy than inside it. So the field would need to have low strength "pockets", one for every galaxy. In addition, magnetic fields have an orientation, and for this to have any chance of working right, would have to be oriented properly for each individual galaxy. But galaxies are not all oriented the same, so the field would have to have different orientations at different points. This runs contrary to how magnetic fields behave. So your idea involves invoking a "magnetic field" that behaves nothing like a magnetic field would.
  3. Finnish: kuusi palaa could translate to any of the following: The spruce is burning The spruce returns The number six is burning The number six returns Six of them are burning Six of them return Your moon is burning Your moon returns Six pieces
  4. I remember seeing it back when it was originally aired.
  5. Further objects only have a larger red-shift due to the fact that the universe is expanding. If the universe did not expand, there would not be any change in red-shift with distance. The amount that the red-shift of any particular galaxy will have changed over the period we have been measuring them is too small to notice. But that doesn't mean that we can't measure how fast the universe was expanding in the past. When we look at the light from a galaxy, that light tells us the state of that galaxy when the light we see now left it. The further the galaxy is away from us, the longer it takes the light to reach us. Thus, as we look at galaxies further and further away, we are seeing them as they were when the universe was younger and younger than it is now. That includes how fast they were receding from us, and the red-shift that the recession produces. If the rate of expansion had been constant over time, you would see a one to one relationship between distance and red-shift measurements of recession speed. If you measure anything else, that means that the rate of expansion has changed over time. It is that simple.
  6. What are the same are the speed of light (in a vacuum) and the speed of gravity waves. Gravity waves are not gravity itself, but more like ripples traveling through the gravitational field. Put another way, you can't have gravitational waves without there already being a gravitational field, but you can have a gravitational field without gravitational waves. Light interacts with the gravitational field, which is "already there" As already mentioned, light has no "rest mass". However, it still can interact gravitationally. While in Newtonian physics you need mass to do so, under our more recent understanding of gravity(General Relativity), mass is just one factor that can contribute to gravity. Energy is another, and light does have energy.
  7. So I assume either Norway or Sweden or possibly Denmark? (Finland is not actually a part of Scandinavia). My paternal grandfather was born about 100 miles south of the Arctic circle, and some ancestors from further North.
  8. Ah, but here's the beauty of it: Everyone will be wanting to go to Canada, but only 0.2% of the US population has any claim to Finnish ancestry at all. Having 4 Finland-born grandparents should put me at the front of the line! (Besides, I was born and raised in Northern Mn, cold is nothing new to me.)
  9. Today I learned, that if I chose to, I could move to Finland. If you want to stay in Finland longer than the 90 days allowed by a visa, you need to apply for a residence permit. Here are a few reasons you could be granted one: You've been hired for a job in Finland. You have immediate family( spouse, child under 18.) that already live there. You are going to school there... But the one that would apply to me is "remigration"; If you have Finnish roots, or a close connection to Finland. So, for example, if a grandparent had been born in Finland. This is me. All 4 of my grandparents were born in Finland( as were their parents, and so on) And while most of the other methods of getting a residence permit requires that you can show that you have sufficient funds/income to support yourself, remigration doesn't. Not that I have any plans to do so, but it is nice to have it my back pocket in case things really go sour here in the US ( civil war breaks out, e.g.)
  10. The maximum mass for a neutron is star is ~2.17 solar masses, and one that massive would have a radius of ~15 km. The event horizon for a BH with that mass is ~6.43 km, and has a photon sphere at ~9.65 km. At the surface of the Neutron star, escape velocity would be ~ 0.463 c and orbital velocity would be ~0.33 c, both well short of c.
  11. They say it this way when trying to communicate the idea of non-euclidean spacetime to a general populace that has no idea what non-euclidean geometry is. The animation is not meant to represent "reality", it is a "translation" of non-euclidean geometry using euclidean geometry. It is an attempt to represent an abstract concept in a way that is easier to visualize.
  12. Well, for one, the mechanism you use to explain this frequency shift ( quoted above) would not result in the type of frequency shift we see. All these types of interactions are wavelength dependent, meaning that the effect you get from them depends on the wavelength of the light (An example of this type of wavelength dependent effect would be light at the blue end of the spectrum being scattered more by our atmosphere*) Thus you would see different amounts of shift in spectral lines at different points of the spectrum, and not the uniform shift we see across the whole spectrum. It's not enough to say you can relate energy to frequency when the mechanism that you attribute this change to would not produce the results we observe. * In fact, the very mechanism you base your argument on would also produce scattering. We do not see significant scattering in light from distant galaxies. (because, quite frankly, there isn't enough stuff out there between our galaxy and them to produce it. The amount of material a photon passes on its way between a galaxy 13 billion ly away and our galaxy is roughly equivalent to the amount it passes crossing 1 meter of air at sea level.)
  13. Exactly, a lot of this background on " how things work" on a starship(BTW, the info I provided came from the Star Trek The Next Generation Technical Manual by Rick Sternbach and Micheal Okuda ) are loose guidelines to maintain some continuity, but they are not allowed to get in the way of a good story line.
  14. Most likely by magnetohydrodynamic generator. Where you pass plasma through a magnetic field to generate electricity. This seems to fit with other nomenclature in the franchise. There are references to the EPS (electro plasma system), which seems to be how they tap energy for running ship systems from the PTC (power transfer conduit), which contains and carries plasma from the matter-antimatter reaction chamber to the warp field generator coils.
  15. Moon's don't just "fall" or "lose orbit", as that is not how orbits work. As far as arriving at a conclusion via "common sense" goes, in my experience, it very often is actually arriving at a conclusion by starting with insufficient or just plain incorrect information, and then applying faulty logic to it.
  16. And then there is the fact that Pangaea is just the most recent of a series of super-continents that formed and then broke up.
  17. The second image is an analogy which visualizes space as being 2 dimensional and bent through a third dimension. It is not representative of reality. In it all of space is the surface shown as a grid. And while the diagram shows the Sun and planets as solid objects sitting on that grid, they would better be represented as circles on the surface. Like already stated in order to make it simpler to present, 2 of the spatial dimensions are removed. Here's am animation that gives an idea of what this same analogy would look is you included the other two dimensions The other thing to keep in mind is that the "Curvature" of space-time is not an actual bending of anything. It is a term used to convey the idea that space-time deviates from the rules that govern Euclidean geometry in the presence of mass. It is called curvature because it gives results like those you would get if you try to do plane geometry on a surface that is not flat.
  18. To build on exchemist's point. Let's assume your flywheel is a magnet, and you've placed a coil nearby, but not touching it in any way. Essentially making a "frictionless" generator. Your flywheel will continue to rotate unabated until you attach some type of load( say a light bulb) to the leads of your generator. When you do this, current begins to flow through the wires including the coil. This, in turn turns the coil into an electromagnetic, the polarity of which will apply an opposing force to the flywheel, slowing it down. Keep the light hooked up long enough, and the wheel will stop spinning entirely. Even there were no losses in the system, the total light energy produced by the bulb could only ever equal the total KE stored by the flywheel (which you would have had to have added to spin it up)
  19. The point is that this "down" is the same for everything in the solar system and they all react equally to it. While the planets do "fall" towards the center of the galaxy, they do not tend to do so any more than the Sun does. The solar system is so small compared to the distance to the center of the galaxy, that any difference in gravity acting over it caused by the galaxy's mass is insignificant. ( a quick calculation indicates that some nearby stars would have a larger effect.) Secondly. Even if there was a measurable differential across the solar system, it would not cause the orbital plane to align with it. The solar system is a rotating structure, and when you apply a force in order to try to change the axial orientation of a rotating structure you get a precession instead. (the axis "wobbles") Now, since the rate of this precession depends on a number of factors, including the angular velocity of the rotating structure, and each planet orbits the Sun at different angular velocities, each planet's orbit acts as a singular rotating structure with its own independent precession rate. Thus, over time, you would end up with planets orbiting at all kinds of orientations to each other and not nearly in the same plane as we have now. The fact that all the major planets, for the most part, share the same orbital plane shows that there has been no significant force acting on it in this way. If Saturn's rings were oriented toward the Sun, then we would not see them as well as we can from Earth (since we'd always be looking at them nearly edge on.) Sure, twice an orbit, the ascending or descending nodes of the rings align with the Sun, But since the ring orientation remains nearly fixed relative to the stars as it orbits, this has to happen no matter how they are oriented.
  20. The only effect the gravity well of another body would have on the orientation of the orbital plane of our solar system would be through tidal forces( the part of the solar system closest to the body being pulled on more than the part further away)* Tidal forces fall off by the cube of the distance. This means that the mass causing them generally need to be fairly close. For example, even though the Sun is nearly 27 million times more massive than the Moon, the fact that the Moon is 1/400 the distance of the Sun results in it having the larger tidal effect on the Earth. There are no bodies with the right combination of mass and distance to produce any significant tidal effect on the Solar system. The galaxy itself is very massive, but its center is so far away that, for all intents and purposes, all parts of the solar system are an equal distance from it. The perihelion and aphelion of the various planets do shift over time, but that's due to interactions between the planets themselves. They also do not line up with each other. In addition, while the major planets do tend to orbit in almost the same plane, there are plenty of bodies that do not, asteroids, comets, etc. Comets in particular have large, very elliptical orbits, and because of this, they would be much more prone to be effected by external tidal forces acting on the solar system as a whole. We do not see any pattern to them that would suggest that they are being effected in such a way.
  21. To expand of swansot's post: When you look at the spectrum of a distant light source like a star or galaxy, the spectrum will contain bright and dark lines. These are the emission and absorption lines from the different elements in the source. Every element has a distinct pattern of lines that occur at a particular point of the spectrum. If the light from the source is absorbed/scattered, you will see a dimming of a certain part of the spectrum, but those lines will still be there, in the same pattern and same part of the spectrum because all that is happening is that you are receiving a smaller proportion of light from one end of the spectrum. With red/blue shift, what we see is all these spectral lines shifted to new positions in the spectrum. So for example, a pattern that normally is in the yellow part of the spectrum will move towards the orange. You may not even notice much of a change in the overall "redness" or "blueness" in the spectrum as a whole, as non-visible frequencies shift into the visible at the red end, and visible light at the blue end shifts into the non-visible range.
  22. Masks serve a dual purpose: Protection of the user from others who may be infected, and protection of others from the user if he/she is infected. And of the two, they are more effective with the later. Valves in the mask work to defeat this by allowing more water droplets to escape the mask. People need to to stop thinking of masks in terms of something they wear to "just protect themselves", and more as something that we, as a community, should wear to protect each other.
  23. 10,000 meters in the track frame. If the lightning strikes occur 100 m apart in the train frame, then scorch marks they leave on the tracks are 100 m apart as measured from the train frame. Since the train measures the track as being length contracted by the same factor ( 1/100) as the track frame measures the train, then the proper distance between the scorch marks as measured from the track frame is 100m x 100 = 10,000 m. Of course this means that the rear of the train ( being only 1 m long as measured from the tracks) reaches the point on the tracks where it and the tracks are hit by lightning while the front of the train is still 9,999 m short of where it will be struck by lightning, making the lightning strikes non-simultaneous in the track frame.
  24. While a Moon's tidal influence can dominate, the star will have a tidal influence. For example. Let's start with a planet-moon system tidally locked to each other, The star will still will still produce tidal effects that will produce drag on the Planet's rotation. If this were allowed to happen, then the Moon would orbit faster than the planet rotates. In this situation, the Moon would spiral in, transferring rotational energy to the planet, speeding up its rotation. So what happens is while the Moon does end up keeping the planet tidally locked to itself, it does so at the expense of it's own orbital energy. Both it's orbital period and the rotational period of the planet shorten. However, this can't be maintained forever, as eventually the moon would spiral inside the Roche limit and break up. How long this would take depends on the tidal influence of the star. For example, Proxima Centauri B orbits so close to its star that the stellar tidal forces on it are roughly 1000 times that of the Sun on the Earth.
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