wayne_m

When I said CO2 would become poisonous, I meant that in high concentrations, we can't exchange enough out of our bodies, and blood becomes more and more acidic. This is the reason that we feel an urgent need to take a breath, after holding it for an extended period of time. Even if there is plenty of oxygen in the air, if there is too much CO2, you still die. The poison is the dose.

A linear rise in gas concentration does not equate to a linear rise in absorption of radiation. There is only so much energy to be absorbed. Typically, as gas concentration rises, absorption increases by logarithmic reciprocal. This kind of conversation is usually about CO2, so I'll just say that the change in absorption between 400 ppm and 800 ppm is vastly less than the change between 200 ppm and 400 ppm. In fact, the greatest rise (by orders of magnitude) happens well before 100 ppm. CO2 will become a threat as a poison before it becomes a serious threat due to heat. Add to that that the atmosphere is a stew of many different gases, all with different chemistry and physical characteristics, and you can know one thing: anyone who claims to understand it completely is lying to you. Anyone who claims that his model is definitive is trying to sell you something.

"A little song, a little dance, a little seltzer down your pants" It took a while, but my memory was finally jogged! Chuckles the clown. One of the funniest episodes from the Mary Tyler Moore show was when he died. How did I not remember this?

I've pondered this while driving long distances. I'm odd, that way. There really is no reason that it should be impossible. Insanely expensive, sure. But not impossible. Lower some strands from your geosynchronous station, and support a secondary platform, while extending a counterweight. Then from the lower station, lower a smaller number of strands to a smaller platform, and so on, until it reaches the ground. Once you have a functional elevator, use it to haul more building materials to the station, and begin making it stronger. There is no real reason a cable has to extend the entire distance. This could work with just about any material, but obviously, the station and its cables would have to be a great deal larger (and thus heavier) to support the weight as the elevator gets longer. The reasons we haven't done something like this are 1) it would be hideously expensive, and 2) the cables would oscillate, and without some way of damping that oscillation, it would eventually tear itself apart and/or yank the station out of orbit. If such a thing could be started, then it might even be a good idea to transport the building materials up through a pipe, as a liquid, and make the cables on the station. All sorts of materials could be carried up suspended in a liquid medium - we could even use magnetic medium in the liquid and an electromagnetic driver to act as a "pump" to move the fluid. The magnetic particles would be pulled along much like the mag-lev trains already in use. They would drag the fluid - water, perhaps - along with them. Letting it fall down another pipe after the payload is separated would provide some return energy. Then you'd only be spending energy to overcome the effect of gravity on the payload and the fluid resistance from the pipeline - unless you could separate the liquid from the walls of the pipe, in which case, it would flow much faster, as an added bonus. Using a flow of gas instead of a liquid could work, too. You could even put stations on the platforms that would reduce the lifting medium at each step, as gravity becomes less of a hindrance. Then the concentration of the payload would increase each time. Or maybe an osmotic pipe could let it happen gradually, with better efficiency.

That's something I have a hard time understanding. If the reflected photon carries away the energy it brought into the collision, where does the equation get the energy that goes into changing the momentum of the sail? Do all of the photons reflect, or do some get absorbed? Do the ones reflected just lose energy to a drop in frequency?

If you look at the base of the bulb, you will see the hoax. It can unscrew from the plastic globe to insert a battery.

There's heat capacity and there's heat conductivity. A high capacity material can feel warmer to the touch if its conductivity is low, because even though it will absorb more heat, it will do it more gradually than a lower capacity material that can transfer the heat away from the point of contact more efficiently. That is why a chunk of cold lead lead wrapped in a towel will feel warmer than a glass of water of the same temperature. The lead will eventually absorb more energy, but the glass will carry the heat away from your hand relatively rapidly. The same thing happens with a wooden tabletop or chair vs a steel surface. The wood, being more massive, will hold more heat than the thin metal, yet it feels warmer - initially, at least. After prolonged contact, the steel will have absorbed all the heat it can, and after the same time in contact, it will feel warmer than the wood, which is still absorbing and diffusing heat through its mass. Of course, the steel will be cooling from the other side, so once the wood has had time to absorb enough heat, it will feel warmer than the steel again, since it is a better insulator against the heat loss to the air.

What about the water vapor in the air in the top half?

A theoretical guitar string may have a perfect sine wave as it vibrates, but that vibration causes resonant vibration within the instrument, which complicates the waveform. Every piece of the instrument will have some small effect on the form of the sound wave emitted, and there is no way that any two wooden instruments could produce exactly the same changes in the sound. They can be extremely close - maybe even enough that a human ear couldn't detect the difference - but they will be different.

WBAGNFARB = Would be a good name for a rock band. We got a lot of use out of this on another forum I used to frequent. Example, someone mentions "Occam's razor." Occam's razor WBAGNFARB. This could be used for so many terms of physics and astronomy...

Ow, ow, ow... I'm not even good at Latin, but it still hurts. Dictare - to speak, videre - to see "Altum sonueram," maybe? Or "...scriptus sit...?" [edit again] Okay, now that I've had time to google around a bit... ...How have I never seen these lists of useful Latin phrases?

Out of curiosity, where did you get the tagline? It's a bit confusing; the cases don't seem to match. Minimus is nominative singular, but cantorum is genetive plural. Balorum isn't even really a word. "Carborata" might be a play on carborundum, so sand? It's not Latin. "Panto" means "everything." I'm guessing, by context, that whoever wrote it meant "trousers." Unless it means that a little carborata makes everything fall down. Maybe it should be: "Candantus minimus, Ballandus minimus, Bracca mea arenam minimam labendo" (A little singing, a little dancing, a little sand [going] down my trousers)

If they are lighter than water, float them. One will float higher or lower than the others. If they are heavier, drop them in and see which one takes more or less time to hit the bottom than the rest.

Is it really half empty, though? https://what-if.xkcd.com/6/

An architect, an electrician, and a civil engineer were discussing religion. The architect said, "God must have been an architect. Look at the human body! Such elegance of design! A structure that is strong and light, and allows mobility, coupled with an efficient and effective motive system..." He's interrupted by the electrician: "God must have been an electrician. Look at the wiring system. Self-powered, and such intricate connections throughout the whole body..." They both notice the civil engineer shaking his head. He says,, "God must have been a civil engineer. Who else would run a toxic waste pipeline through a recreational area?" And for our Jewish friends: Two Jewish mothers were sitting in a restaurant. The waiter came to their table and asked, "Is anything all right?" An MIT student takes his girlfriend to a local bar. He tells the bartender, a classmate, "I'll have an H2O." The girlfriend says, "I'll have an H2O, too." So many punchlines for this one. He didn't care for her reaction, when she drank it. The date went well, until she blew up at him. Turned out to be a pretty hot date. The bartender gave her water, because he's not a complete idiot.

A somewhat more likely explanation is space contraction. I don't know off-hand how it relates to time dilation, but spatial contraction is the explanation for why the planet mercury is moving "too fast" in its current orbit. If space contracts, its density would change, and just as with any change of density, it would refract light. So maybe refraction is the answer, rather than gravitic attraction? It would answer the question of how a massless particle could be affected by gravity. But it would pretty much require that there be something in empty space that has "density" that changes when it contracts. I've never heard anyone propose that sort of thing. Path length might work - Since light cannot exceed c objectively, if the path inside a gravity field is shorter due to contraction, it would have to emerge from the field having traveled an internal distance that would be equal to the chord distance across the field for the angle at which it entered. Thus, it would have to change angle until the chord (or arc) inside the field was of equal length to the chord line from the objective frame of reference. Thus, gravity would not have to act directly on the photon to make it curve.

Interesting idea. As a wave, the photon would approach and retreat from the gravity source, and as it gets closer, travels more slowly, and as it retreats, more quickly. Within the effect, from the photon's frame of reference, it would not change speed, but from the outside, the effect would be observed. But the gravity would have to be pretty intense to have such a differential effect at the scale of the wavelength of observable light. We see it in much less intense gravity fields, so it is probably not the explanation.

The place where I work stretches metal sheets. Of course, we use presses that pull sheets over dies with hundreds of tons of force, but it's what we do. If we're allowed to stretch the material, then we could make a tank of any size, though if it gets large enough, the water pressure at the bottom would burst the thin material Of course, if we assume material strength holds true to that extent, then we have to allow that the material would break before we stretched it that far, unless we did it at a high temperature and with a special press or roller. It would be more economical just to buy more material.

That's why I posted here: To see if anyone who has studied this sort of thing in greater depth than I have would know whether it could even be possible, and then if it is, whether it would be efficient enough, energy-wise, to be worth considering. It wouldn't be "reactionless," because we are pushing on the mass within our system for reaction. We are just using the change of mass in a lump of matter as we speed it up to relativistic speeds and then slow it back down again. The questions are whether we can direct the energy of the system where we want it to go, and whether the energy difference between frames (our moving ship and the universe at rest) would make it work to bring those frames closer together. Well, we are slowing a ship to rest with respect to the outside frame - the frame of the star system where we've just arrived at a very high rate of speed.And now that we're here, we need to stop, unless we're just taking pictures as we pass through on our way to the next system. The ship and the universe are the outside observers of our mass that we're using as a brake. From either frame, the mass is moving near c, so its mass has increased from our perspective, and we need to "push on it" ever harder to accelerate it, due to its increased mass from our perspective. So my understanding of relativity is that we now need to accelerate some matter to near c (from the frame of the ship - but it will actually get closer to c in both frames) and it will gain mass. The closer we get it to c, the more massive it is, and thus, accelerating it with more force will make the brake more effective, since we're pushing it against the motion of the ship. That opens the question, now, whether the energy required will still be the same as accelerating it near c from absolute rest (i suspect it would) or slightly less, since it is already moving objectively at .5c Either way, any energy used will be directed to slowing the ship. Since we have no way to cancel inertia, and we don't want to splatter our crew against the bulkheads, we would have to slow the ship gradually, so the mass in the system would be cycled through the system many times. (unless the ship is really long ) This means that there would necessarily need to be some way to slow the mass without re-accelerating the ship. Thus the question about how much of the energy would be transferred back to forward motion as we vector (again, in terms of thrust, not math,) the mass away from the axis of the ship. If the mass is still moving at or very near the speed it was moving before we started vectoring it, would it carry that energy "sideways" and not "redeposit" it axially? And upon this consideration, I have to wonder: if this sort of setup didn't transfer all of the energy back to forward motion, would it be useful for propulsion, if used in reverse? For some reason, I think that I've considered this before, and proved (to myself, at least,) that it wasn't possible. My impression is that the system would have no acceleration from the frame of the ship, and therefore, as the ship's frame approaches the frame of the rest of the universe, it would have less effect until the frames matched (not really possible, in this scenario, but for the sake of argument...) at which time, it would not have any effect at all. My understanding is also that mass increase is not terribly great until you get pretty close to c. So at .5c, your ship (and your reaction mass) would only mass about 15% more than it did when it was stopped. But once you get up to .99c, it masses about 7 times as much, and at .9999c, ~5000 times as much.At the moment, I'm not worried about the machinery that would accelerate the mass to these speeds. A genie came out of his bottle and gave it to us. It works. (See: "Given" section in OP.) But "it works" is not the same thing as "the machine does what we want it to do." As a final note, I know that I made a few mistakes in the original post. It was way past my bedtime, and I'm working from a vague memory of something I thought about years ago but finally decided to ask. Feel free to point out any errors, but try not to be too hard on me

I understand this poster's request and situation completely. I, too, like knowing how things work, without having to slog through mounds of math. I want to understand the concept, and often have no desire to build the object in question, so do not anticipate having the need to understand the math involved. It may be that because I do understand the math behind most things, even if I'm not willing to go through all of the work of crunching the numbers, that I find these things fascinating. I've explored a lot of different disciplines, and worked out a design for a chip that can combine electronics, physics, and chemistry to produce gasoline out of thin air and electricity. (Works better with liquid water and CO2 feedstock.) But it isn't something I would ever try to build: It would be quite expensive to produce, and assuming perfect energy efficiency, would only produce roughly a gallon of gasoline per week per square meter of solar power. (and grid electricity would cost me half-again as much as just buying it at the pump.) What with the time and materials, even "free" gasoline at that rate would take me a couple dozen years to recover my investment. Since there are so many factors where efficiency suffers, I could expect a gallon or two (at best!) per year per square meter of solar power. Not worth the time to build, but fun and educational to design. Granted, I did have to do some math, but not as much as I would have needed if I were actually trying to build one. So I don't really need to know how to calculate a Henry is to know how a tank circuit works. All I really have to have are the concepts of capacitance and inductance. Maybe someday I would learn enough, and get curious enough to investigate the interactions that make a signal radiate more from the side of an antenna with the director near it, and/or away from the reflector element, but if all I want to know is how the old RCA in the attic works, I don't need any of that. Keep asking questions, Joe. It's one of the best ways to learn. I've found that the best way to learn anything, though, is to teach it to someone else. Teach it to your little sister. Or your cat. The point is that teaching a subject will show you the areas where you are weakest, and have the most to learn.

And in the army (I kid you not,) I've heard it called an "Apparatus, terrestrial reconfiguration, manual."

Praise without end for the go-ahead zeal Of whoever it was who invented the wheel! But never a word for the poor soul's sake Who thought ahead, and invented the brake. I've seen a lot of ink spilled (electrons manipulated?) about massless propulsion, and I realize that it could potentially be used to accelerate a ship "in reverse" to act as a brake, but how would its energy consumption stack up against the following idea, assuming the idea could even work? Given: Some form of drive has been developed that can get a ship up to a significant fraction of c Given: A power source sufficient for the job and materials that could withstand the rigors of use Given: Relativity tells us that an object increases in mass geometrically as it approaches c Hypothesis: Accelerating matter (solid, liquid, gas, plasma, whatever,) forward in the ship will cause the mass to increase, and provide reaction mass which we can use to slow the ship. Now, after the matter has reached its peak mass, and we have used it to slow the ship, we vector it back around so that it is now moving toward the rear of the ship. Now we circle it back around and prepare to recycle it. Situation: The ship is moving at a leisurely .5c, and we start accelerating the matter to about .49c before it reaches the end of its tube. We have accelerated it to .99c or thereabouts (objective reference) and it is becoming very massive, and providing a good "space anchor." Or parachute. Pick your metaphor. The fuzzy bit - The part I haven't had enough time to ponder and figure out: As it is vectored (vector as in thrust, not as in math,) around 90 or 180 degrees, it will start losing mass, since it is slowing in the objective frame of reference, until it is traveling toward the rear of the ship - slower than the ship, in the objective frame, so it has (slightly) less mass than when it started. We can assume that the matter is flowing down a tube and then migrating radially (inward or outward, doesn't much matter,) to the return tube, and thus the lateral thrust is evenly balanced. We could even begin slowing it in the lateral section, so that any "thrust" from slowing the matter cancels out and is turned into tension on the materials of the braking device. The question, then, is how much of the energy contained in the mass will be returned to forward motion of the ship as its path is bent through the 90 or 180 degrees of the brake. Where would the energy stored in our highly massive matter go as we slow it back to near-rest (objectively?) Could it be captured and used to continue accelerating our reaction matter? Sadly, this brake could most likely not be reversed to produce positive "massless" thrust. anybody have any thoughts on this idea? The reason I wonder how it would compare in efficiency is the old conundrum of space travel: Okay, how do we stop, now that we're here? Sure, we could turn the engine around, but what if there were a more efficient way? We don't throw our cars in reverse to stop, once we reach grandma's house. We discard the energy through the brakes. It's more efficient that way.

SSS SCC C SC SSS Straight, Straight, Straight Straight, Curve, Curve Curve Straight, Curve Straight Straight, Straight, Straight ABCDE No hints. Just OCD (I know the thread is over a year old. I just got here, though, so it's new to me.)