Janus

The total amount of dark matter in the entire solar system is estimated to be about equal in mass to a small asteroid spread out evenly throughout the solar system. The amount inside the Sun would be expected to be around the same density as it is everywhere else in the solar system. If you take the extent of the solar system as being out to a distance of Neptune's orbit, the total volume of the Sun is 1/3e11 that volume and thus you would expect to find about that fraction of a small asteroid's mass on DM inside of it. DM would not tend to collect inside the Sun. If you start with a particle of DM falling towards the Sun, it will just fall faster and faster as it gets nearer. When it reaches the surface, it just keeps falling, picking up more speed. It passes the center and begins to climb out, back past the surface on the other side and back out into space again. The most the Sun's gravity does is bend that trajectory, because there is nothing that will slow it down so that it can be captured by the Sun. This is different than visible matter, which once it hits the surface is slowed down by the Sun so that it loses the speed it needs to climb back out again and it is captured.

While there is more total dark matter in the universe, it is spread out much more thinly. Black holes tend to form in the same places as stars do. In the galactic disk, for example. The average density of interstellar material is ~ 1 proton mass/cc, The estimated dark matter density in the region of the solar system is 1 proton mass/3cc or 1/3 the interstellar medium. The average interplanetary medium in the solar system at Earth orbit distance is 5 proton masses/cc, (and can range as high a 100 proton masses/cc) So just by relative density alone, you would not expect the in fall of dark matter to make up a majority of the mass falling into a black hole. Now add to this the fact that visible matter, on its fall inward collides with other visible matter. This results in the production of radiation that comes at the expense of the KE of the matter involved. Thus a bit of matter originally on a course that would take it on a hyperbolic path around the BH with a periapis outside of the event horizon can lose energy in such a collision and have its trajectory crossing the EH. Or it could be put into an closed orbit around the BH. In this case, it is subject to collisions with other orbiting particles, further robbing it of KE until it does fall in past the EH. DM, on the other hand doesn't collide, has no such mechanism for shedding energy, and thus will only cross the EH if its original trajectory takes it there. The end result is that the black hole is effectively a larger target for visible matter than it is for dark matter, which is compounded by the fact that in the region surrounding black holes, you are going to have a higher density of visible matter than dark matter to start with.

First of all, you have to consider what happens when you "bump into" everyday matter. The interaction between you and that matter is all done via electromagnetic fields. The electromagnetic fields in the matter interact with the electromagnetic fields of the matter which you are made of. So the "solidness" any object is just due to this electromagnetic interaction. This electromagnetic interaction is also responsible for the objects interaction with light or any other frequency of the electromagnetic spectrum. They are reason they glow when hot or absorb, reflect, or scatter electromagnetic radiation. Dark matter, by its very nature, does not interact with light in this manner. It is completely lacking in electromagnetic interaction ( like the aforementioned neutrino). Thus it also would not participate in the type of "bumping into" interaction everyday matter does, and thus passes right through you pretty much like you weren't there.

If we use the numbers given of a 5% larger radius and a 5% larger mass, then the surface gravity would be 1.05/1.052 = ~0.95g. It would be the escape velocity that would be 5% higher, Though I 'm not sure that this would be enough for the planet to hold on to its atmosphere. Being as close to its parent star as it is would subject it to quite intense solar winds. Not to pry, but how much do you weigh?!! 3 times the mass and a 60% greater radius gives a surface gravity of 1g x 3/1.602 = ~1.17g So unless you presently weigh over 500 lbs... It would be a bit tougher to leave however, with an escape velocity almost 1.9 times that of the Earth.

If he is just talking about purging them from someplace like the Hawaiian islands, mosquitoes aren't native to those islands and were brought in from the outside. So, if anything, you would be removing an "invasive species". The island ecosystem was just fine before they came and would survive their departure.

https://en.wikipedia.org/wiki/Amphicar I actually saw one of these back in the '60s. We had just finished a day on the lake with my uncle's houseboat, when we saw one come in off the lake, up the boat ramp, and drive off. The flying part is another issue. Your idea of small wings on the wheels just wouldn't work. There is no way that they could generate enough lift. While there are some designs for flying cars that use a four propeller system somewhat similar to used by drones, those propellers are set out quite a bit from the body of the car and use cowlings to maximize lift. And the idea of such " multipurpose" wheels is just bad from the get go. It's just too fraught with things that could go wrong. When you are up in the air , the last thing you want is to have to rely on an overly complicated system to keep you up.

I had read the book, but my wife hadn't, so we while we watched it from different perspectives, we both enjoyed it.

Our daughter got us a ROKU a few years ago. At the time we had a fairly low end internet connection speed, and it really didn't get much use. It wasn't until a couple of years ago when we upgraded our internet, that we got the Netflix set up. Hulu came later (mainly because my daughter wanted us to watch a series she really loved (Timeless), which was on Hulu ( not a Hulu original but a canceled network show). Just recently while we were over at their place, we happened to mention that we had just recently caught a couple of episodes of Good Omens while spending the night at a place that had Amazon Prime.( I've read the book a couple of times, and remember being excited when I heard it was going to be made for TV, and then disheartened when I learned it would be on Amazon Prime, which we didn't have). That's when my daughter's boyfriend offered to set us up with it. One nice thing about the Roku is that it allows us to watch Yahoo! sports on our TV. Normally this would not be that big a thing except that we do like to follow our local NWSL team (Professional Women's Soccer team), and their games are very seldom televised, while Yahoo! sports does stream the games.

The Walking Dead (though I must admit that my enthusiasm for the show has waned. It's almost a "Not wanting to give up on it after investing in it for so long" more than a "can't wait for the next episode". The Good Place (though this is ending after this season) Supernatural (my wife actually was the one to start this one, I just started watching because it was on in the background. Another show in its last season. I do also watch The Flash On Netflix we'll watch The Kominsky Method, Stranger Things and enjoyed the first season of Lost in Space, We are currently catching up with The Marvelous Mrs. Maisel on Amazon Prime (We just finished Good Omens) I heard that the Orville is switching to Hulu. so that'll be a streaming series also. If it wasn't for our daughter and her boyfriend, I doubt we would have sprung for any of these streaming services on our own, they set us up with all three.

While the efficiency of the combined pair would be the result of the combined efficiency of the two devices, it wouldn't combine to improve the overall efficiency but to decrease it. If you compound a 99% efficient device onto a another 99% efficient device, you end up with less than 99% end efficiency for the combination. It is the loses inherent in each device that add up.

A comet moving at that speed "coming out of sun" as it were would have to be on the outbound leg of a narrow elliptical orbit, that extends past Earth orbit. We hardly would have missed it on its inbound leg. We would have watched it, and calculated its outbound leg. While this might not give a perfect solution, we would know approximately where to look for it as it rounded the Sun and found it again fairly easily.

Extremely large, no. the larger the object, the easier it is going to be spotted at a further distance. The only objects that really catch us by surprise are relatively small ones. For example, in Jan of this year we were buzzed by a small object which we didn't notice until after closest approach, but it was only estimated to be less than 2.5 meters in size. On the other hand, in 2001, an object was discovered which is predicted to make a close approach in 2028. This object is estimated at 0.6-1.4 km in size. Generally, the longer you have to observe an object, the better you can nail down its trajectory and any future encounters it may have with the Earth. But even then, there is an upper limit to how far into the future your prediction in likely to be accurate. The longer the time between detection and possible impact, the more time that the object's trajectory can be perturbed by outside influences. With comets, this can be particularly challenging. A comet is basically snowball of frozen water and some gasses. As it comes in from the outer solar system, these start to boil and evaporate, and not necessarily evenly. Pockets can erupt on the surface, which in turn can act like rocket engines, making small adjustments to the comet's trajectory. This can effectively reduce the accuracy of long term predictions of its orbit. ( and it doesn't take much to turn a miss into a hit or vice-versa, It only takes the Earth 7 min to travel the width of its diameter, so an object crossing Earth's orbit just 8 min later or earlier could make all the difference*.) *Actually, a lot depends on the object's relative orbital velocity with respect to the Earth. Both the angle of approach relative to the Earth's orbital direction and the relative speed. Relative speed plays a role by determining the impact parameter. Any object approaching the Earth will be affected by its gravity. Thus an object which would have missed the Earth otherwise can have its trajectory curved towards the Earth, making the Earth a "larger target" than just its diameter might suggest. The faster the object is moving relative to the Earth, the less time the Earth's gravity has to deflect its trajectory, and the "smaller target" the Earth makes. Conversely, it presents a larger target to slower moving objects.

Maybe because the energy produced wouldn't even be enough to heat the water for the shower you'd need afterwards. At best, you'd would be off-setting the power usage of your exercise equipment, and I already pointed out, there are already elliptical machines out there that do this.

One issue is that, with a electrical generator, the fast it turns, the greater the current it produces, which in turn results in it taking more effort to turn it. The faster you walked or ran, the greater the resistance of the treadmill would be. Generally, you want to set the resistance of your electrical equipment and have it remain constant no matter what speed you are going. So a direct treadmill to generator hook-up isn't the best option. Instead, you would need to add some sensing equipment that measures the current output and makes adjustments accordingly. Some elliptical machines are designed to do just this. Many models use magnetic braking; the machine moves magnets either closer or further from the flywheel in order to create the resistance. There are also "green" models that use this to generate the electricity operate the electronics for the machine and allows you to use it with having to hook it up to an exterior power source. This scheme would likely work for a stationary bike, using the same idea. Both of these completely rely on the user for setting the pace. However, when it comes to the motorized treadmill, the idea behind the motor is that it sets and maintains the pace for you. It is a means of forcing you to a steady constant pace. Manual treadmills require the user to control the pace. You might be able to create a hybrid manual treadmill, which works like like the green elliptical. where the user provides the energy for moving the treadmill, and generates electricity for a electronics display used to track your progress.

If that were the case, the time dilation would be dependent of the local strength of gravity, and experiments would reflect this. It isn't, and they don't.

The difference is that they are still afforded the choice, but that their choice cannot negatively effect others. There seems be a growing trend in this country that "freedom" means doing whatever you damn well please no matter how it effects others. If your choice has a negative effect on someone else it's "so sad, too bad". So while you might defend their right to choose, the public also has a right not to be exposed to risks not of their choosing.

Not the point. koti was not suggesting a law forcing vaccinations on those who don't want them, but that they be removed to someplace where their choice will have no effect on the public health. Thalidomide was prescribed to alleviate nausea from morning sickness, not exactly a public health issue. And once the link between it and birth effects was suspected, it took very little time for scientific studies to confirm the link. This is a far cry from vaccination which has been in use for decades with no evidence of them having an overall negative effect.

A hydrogen bomb needs a fission bomb primary to initiate the reaction. A fusion-only bomb is purely hypothetical at this time.

Since the Potassium in a banana isn't going to have any higher a ratio of K-40 than any other natural source of Potassium, if you are thinking in terms of health issues, you have nothing to be concerned about. A person would have to ingest 1000 bananas in one sitting to get enough radiation to increase your risk of death by 1 part in a million. There are no "accumulative" effects either. Potassium is one of those elements that the body carefully regulates. Ingest potassium rich foods, and the body just takes what it needs to maintain levels and the rest is expelled as waste. So you can't get a "build up" of K-40 in your body, and any K-40 in your body is going to be due to the potassium your body needs to function properly. So the only way you could avoid K-40 in your body is to avoid eating all naturally occurring Potassium sources (which encompasses quite a lot of food), and get your potassium via supplements, which have had the K-40 removed. Likely a very involved and expensive process, and unlikely worth it considering the low level risk natural K-40 levels in you body represent. If you are going to fret over that, you'd go absolutely ballistic over the carbon-14 in your body)

There are a number of problems with this. You can't just convert matter into light any way you want. For example, even if we start with something really simple, like an electron at rest. If we were to convert this to light, it would have to be as a minimum of two photons. And those photons would have to leave going in opposite directions. Photons carry momentum, and since your electron at rest had none, the only way to conserve momentum after the conversion is for the momentum of the two photons produced to cancel out. So to get these photons headed both in the same direction, so at a minimum, one would have to have the direction of its flight reversed. This changes its momentum, which would have to be reversed again, upon reaching the destination in order to re-make the original photon at rest. Now while the original reversal could be quite straight forward (just bounce the one going the wrong direction off a mirror), at the destination, you'll have two photons moving in the same direction. How would you go about reversing just one of them? It gets worse if the electron starts with some motion towards or away from the destination. Now, in order to maintain momentum conservation, The momentum of the photons will not be balanced. Since they travel at the same speed, this is achieved by their having different frequencies. Again, one would have to have its direction reversed. So two photons of different frequencies arrive at the destination, with one needing to have its direction reversed. Now above, when the source electron was at rest, it didn't matter which of the photons did this, but now it does. The right photon has have its direction reversed or the resulting electron will be moving in the wrong direction. How does the destination know which is the right one? For that matter, how does the destination decide which pair of photons were produced by the same particle? If you started with two electrons, each with its own stating momentum, 4 photon would arrive at the destination, with no way of telling which pairs went together in order to form the originals. So the only way to "reassemble" those photons back into the original object would be to send a separate signal carrying the info with the original object's specs. For something like a human being, this would mean a lot of information encoded into that signal. The method of collecting, storing and transmitting this much data is far beyond anything we can even dream of at this stage. But, let's assume we could, collect, encode and transmit all that info( And given the limitations built into the universe due to the implications of QM, this is unlikely*), and then use that info to "reassemble" photons back to the original object. Do we really need to convert the original object to photons and send them too? That information could just as easily be used by the destination by creating its own photons from matter on the spot and then reassembling them into a copy of the original. You've really just invented a really complex fax and 3d printer set up. Why go to Sirius, when you can send a copy instead? Of course, maybe you would have to "disassemble" the original in order to collect the needed info. But it would still be just a "copy" that made it to the other end, even if you used the photons created in the disassembly. And you could use that info to make multiple copies. It brings up the philosophical question of whether the copy is really "you", or did you die and were replaced by a doppelgänger? If you decide that it is "you", then you've also invented effective immortality. Every morning, you step into the scanner, and get your template "recorded". Then, if something unfortunate happens (killed in a car accident, etc), This morning's template can be used to "reset" you**. It might even be a good idea to keep earlier versions stored for emergencies ("I'm so sorry Mr. Smith, but the diagnosis came back as cancer, if we had only caught it 6 mo earlier". Or your old heart just isn't what it used to be, So a little tweak and you create a perfect, but un-living copy of your 20 yr old self as the perfect heart donor.) In short, such an ability would have much wider ranging effects than just "I was there, and now I'm here." ** Star Trek the Next Generation made a nod to this by incorporating "Heisenberg compensators" into the transporter mechanism. When asked how they worked, one of the production staff answered "Very well." *The 1965 short story Now is Forever by Thomas M. Disch touches on what type of effect this could have on society.

You understand it wrong. It has nothing to do with light reaching you more slowly. While we do use light in examples dealing with time dilation, this is just a convenience as using light makes the examples clearer. But light itself has nothing to do with the reason for time time dilation. These examples are just highlighting something much more fundamental about the very nature of time and space in our universe. Basically, If we are in motion with respect to each other, we simply do not measure time and space the same. 1 sec for you is not 1sec for me, and one meter for you might not be 1 meter for me. We will not even agree as to whether given events are simultaneous to each other or not. Relativity forces us to accept that the idea of universal time, where one sec is the same for everyone, just doesn't apply in our universe.

It doesn't require an input of energy for an object to continue a constant rotation or a constant linear velocity, but this does not mean there is no energy involved, just that the energy of the object is constant. If an object is moving or rotating as measured from a frame of reference, then that object has a non-zero KE as measured in that frame. Once you said that a water molecule spins at 50,000 rps, you have established that there is a frame from which you are making that determination. And from that frame, the water molecule has a certain rotational KE. And that KE, would equate to a certain velocity relate to the frame if contained by an electron instead. The point is that there is no evidence or argument that supports your initial claim that electrons of an atom ever exceed the speed of light. And while it is apparent that you do need to go back and review Newtonian physics, Newtonian physics is insufficient at the atomic level where QM rules.

The "classical radius" of an electron is 2.8e-15m. Spinning at 1,000,000 rps would have the points at its "equator" moving at ~ 1.8e-8 m/sec, Even if you had it "orbiting" at a radius equal to the largest atom, 1,000,000 rps would only equate to a electron velocity of 0.000016 m sec. This is quite literally slower than a snail's pace. If you calculate the speed an electron orbiting in a an hydrogen atom would need using purely Newtonian physics in order to maintain its orbit, you get a something over 10m/sec. Still nowhere near c, let alone greater than c. And this not even considering Relativity or QM. Even if you were to spin the water molecule, with its much larger than a single atom radius, up to 1,000,000 rps, the fastest any part of it could be moving would be 0.0017 m/sec. High rates of spin simply do not equate to high velocities when dealing with entities with such extremely small radii. Let's also work it out in terms of energy. If we have a water molecule, with a mass of 2.9e-26 kg with a radius of 2.75e-10 m, spinning at 50,000 rps, and we assumed that all the mass was located at the radial distance*, you get a kinetic energy of 1.1e-34 joules. All of this energy applied to accelerate an electron would give it a speed of 0.015 m/sec. So even just a quick examination of the numbers show that to claim that electrons ever exceed c while orbiting a atom is bogus, without even having to invoke Relativity. * this gives you the maximum KE.

And in a great deal of cases, things in nature don't "look designed". Compare the human brain to the aforementioned lap-top. With the lap-top, everything in it has a purpose aimed towards the proper operation of the device. It doesn't have buttons or switches that were needed for earlier computers and no longer have any function now, for example. The human brain however, is a series of more complex structures built on top of earlier more primitive brain structures. There is no indication that its final form arose from any design process. It would be like designing the lap top by starting with a ENIAC base structure, and tacking a IBM 360 architecture on top on that, then adding a 6502, then a 16 bit microprocessor... No sane designer would go about it that way.

For a reference frame with a relative velocity with respect to the guns equal to that which the bullets have relative to the gun after being fired, the bullets start with a non-zero kinetic energy and momentum due to the velocity they have relative to the above reference frame before the guns are fired. The guns firing produces forces that, as seen from this frame act as a "brake" on the bullets, slowing their velocity to zero, and lowering their relative KE and momentum to zero. From the bullet's point of view, they were making measurements from one inertial frame before firing, and a different one after. They spent a brief period in an accelerated non-inertial frame. So while they can infer that they changed momentum and KE in the transition between the two inertial frames, all they can really say is that the KE and Momentum is different after firing than before firing. They cannot say anything about their absolute KE or momentum.