D H
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Everything posted by D H
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That's an urban myth. It's not true. The Coriolis effect is far to weak to have any noticeable effect on how water drains from a kitchen sink. If you fill the sink and then immediately pull the plug, there most likely is some residual angular momentum from the act of filling the sink. This is the key reason you see the water start spinning in a sink or a tub as it drains. Any asymmetries such as an off-center drain hole (e.g., a typical bathtub) will add to this effect. Suppose you do the experiment right: Get your hands on a very large, perfectly circular sink with a small drain in the very center. Close the drain and fill the sink with water. Let the water stand for several days so as to damp out any angular momentum that was added when you filled it. Open the drain. After hours have passed (this is why the drain has to be small) you will start seeing a circulation in the water that remains in the sink. This rotation does come from the Coriolis effect. So why isn't angular momentum conserved? Simple. First off, you're looking at things from the perspective of a non-inertial frame. Secondly, you're not looking at a isolated system. Conserved quantities (linear momentum, angular momentum, and energy) aren't necessarily conserved in non-inertial frames, or in non-isolated systems.
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Why do we not feel the effects of Atmospheric Pressure?
D H replied to Brandon Snider's topic in Other Sciences
Which means it's my fault for not writing clearly rather than the fault of all you readers for misreading what I wrote. Sorry for any confusion I might have caused. -
Countable? You appear to be confusing the concept of sets and numbers. Countability is a property of sets, not individual elements of a set such as pi. You can find many proofs on the net that pi is not only irrational, but also is transcendental.
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The GelfondSchneider theorem says that e^pi is transcendental (so obviously irrational). http://www.wolframalpha.com/input/?i=%28-1%29%5E%28-i%29
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Is the same goof being committed in other planets ?
D H replied to Externet's topic in Astronomy and Cosmology
What makes you think that our current system for measuring angle and time is "senseless"? What would be senseless would be to mindless force the use a decimal system onto something where a decimal model is a bad fit. It would be a case of "a foolish consistency is the hobgoblin of small minds". A decimal-based approach for time works just fine when time is divided extremely finely. Physicists and others use milliseconds, microseconds, nanoseconds, and even smaller divisions of time all the time. The problem is that a decimal-based approach using the second as the unit of time just isn't that good a concept for larger interval of time. A decimal-based approach for time also works just fine when time is looked at very coarsely. Historians, geologists, and astronomers regularly use decades, centuries, millennia, and even larger powers of tens of years. The problem here is that a decimal-based approach using the year (what year?) as the unit of time isn't that good a concept for smaller intervals of time. One issue is the physically inescapable fact that a day comprises 86,400 seconds (plus a few milliseconds; the length of a day is not constant), a year comprises 365.25 days (less a fraction, unless you are an astronomer). 86,400, 365.25, and a decimal-based system don't mix. Redefine the second so there are 100,000 seconds in a day? Good luck with that. You'll break *everything*. We are stuck with the second as the principal unit of time. Even the French had to abandon their decimal-based approach for larger multiples of time in their French Republican Calendar. While a week comprised ten days, a month comprised three weeks, and a year comprised twelve of those months plus five or six "complementary days". The factor of ten approach just doesn't work with largish periods of time. With regard to angle, the most rational way to represent angle is to use a completely irrational approach: Divide a circle into 2*pi parts. -
That's far from the only problem. Another problem is that it's pretty much useless. Consider gold. The total amount of gold mined by humankind is but a tiny, tiny fraction of the amount of gold in the Earth. Almost all of that gold is forever inaccessible. It's locked up in the Earth's core. Almost of the gold and iron that were present when the Earth first formed sank to the center of the Earth as the very young Earth differentiated gravitationally. Even the vast majority of the tiny fraction of gold that is in the Earth's crust is forever inaccessible. It's just too widely dispersed to be mineable. It takes a rather rare set of circumstances for ore deposits to first form, then to stay locked up for a long time, and finally to be exposed at or near the surface. The gold that we mine now was deposited with meteor impacts, most of them during the late heavy bombardment. In the 3.8 billion years since, some of that gold dissolved in water (the oceans contain ten times as much gold as the amount mined by humankind), some got dispersed throughout the crust. A tiny bit was concentrated by biological and geological processes. A tiny bit of that was trapped in stable formations, and a tiny bit of that is finally exposed so humans can find it. The same applies to the other six of the seven metals of antiquity. We would never have risen beyond stone age technology without easy and obvious access to those key metals. We would never have risen beyond iron age technology without easy access to iron, coal, and oil. We had that easy access because we were the first intelligent species to arise on this planet.
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"Buried under rubble" would be what our cities look like in 65 hundred years. This thread is about what our cities would look like in 65 million years (or what 65 million year old dinosaur cities would look like now). In 65 million years, many of our northern cities will be ground to dust by multiple ice ages. The coastal cities will be ravaged by changing sea levels, occasional floods, and covered with deep layers of silt. Cities almost everywhere will be buried by hundreds or thousands of feet deep. They won't be buried in rubble. They will be buried in rock. Perhaps some city somewhere might escape the ravages of time and still be detectable as an city 65 million years later, but perhaps not. That is abiotic oil nonsense. Peak oil is a very real phenomenon. While it's not as bad a problem as the scaremongers would have you believe, it is still a very real phenomenon. The reason it's not quite so scary as portrayed is that previously uneconomically viable fields become viable as oil prices increase. FTFW. Your link was broken. FTFW also. Without that attribution to the source, it appears that you are quoting me as making that statement. This article is a favorite amongst abiotic oil crackpots. Yes, there was a slight increase in production, but it was slight, and now it's just in decline. This apparently was caused by a small, previously unknown oil field seeping into this larger one. Losh, Walter, Meulbroek, Martini, Cathles, and Whelan, Reservoir fluids and their migration into the South Eugene Island Block 330 reservoirs, offshore Louisiana, AAPG Bulletin, 86(8):1463-88 (August 2002). Here's a graph of Eugene Island Block 330 oil production: This was an exceptional case. The exception proves the rule, which is that oil is a finite resource and that we are depleting it. Citation needed, and which "some"? The consensus view is that coal is produced from terrestrial plants, oil largely from phytoplankton and zooplankton. Bury terrestrial plants under anoxic conditions long enough and you get coal (and some natural gas). Bury plankton long enough and you get oil (and some natural gas). They come from rather different sources. Oil does not turn into coal. I agree with that final assessment.
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No, they don't, at least not to the extent they accumulated in the past. The Carboniferous (that's the source of almost all of our coal, and a sizable fraction of our oil) was a period of "life gone wild". Life was significantly more prolific in the Permian and the Jurassic than it is now. The Saudi oil fields are largely from the Carboniferous, the west Texas and Oklahoma oil fields from the Permian and Jurassic. Most of the oil we get now originated over 100 million years ago. That oil won't be available to this future intelligent species because it's almost gone now, and will be all gone by the time we die off. There is some oil that originated less than 65 million years ago, but most of that is offshore (e.g., the Gulf of Mexico, the North Sea, Venezuela). The reason it's offshore now is because that's where it was created (most oil is created in oceans and seas) and because 65 million years isn't all that long a period of time from a geological perspective. The same applies to oil being formed now. 65 million years from now, it will still be offshore. How is this future intelligent species going to know they need to drill to great depths offshore to find oil if they can't even advance beyond stone age technology? There isn't going to be all that much uplift and changing of the continents in the next 65 million years. 65 million years isn't all that long a time in geological terms. Africa will plow into Europe, raising the Alps as high as the Himalayas are now, and Australia will plow into Indonesia (but not Asia, at least not yet). The rest of the continents will still look more or less like they do now -- and depleted of metals. That lack of metals is going to keep that culture in the stone age. Even if they do somehow advance beyond stone age technology, how are they going to skip over the need for coal? It was coal, not oil and gas, that powered the industrial revolution. Coal is old, and it originates from times when life was extremely prolific. Life has not been that prolific since, and probably can't be that prolific ever again. The Earth itself is starting to get old. There aren't many such deposits to lift up, and 65 million years is too short a time span to lift much up. Aside to cladking: Please stop with the off-topic posts. If you want to discuss how non-special humans are compared to other animals, start your own thread. Moontanman, this is your thread, but I'm going to take a crack at refining it so as to avoid the off-topic nonsense. Suppose some species of dinosaurs had developed intelligence and language on the order of humans, only to be wiped out by the Chicxulub impact. Would we still be able to determine that this had happened if, when they died out, they had advanced to: - The equivalent of Homo erectus / primitive Homo sapiens (primitive stone tools only)? - Late stone age technology and started building there first cities? - Bronze age technology (ancient Egypt)? - Late iron age technology(ancient Rome)? - Industrial era technology? - Space age technology (dinosaurs on the Moon)?
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Suppose that 40 years from now some ultimate calamity wipes humanity off the map. For example, nuclear + biological warfare, with nuclear winter and massive starvation wiping out the few survivors. Over the course of 65 million years, our coastal cities would be buried in silt and mud, which will eventually turn into sedimentary rock. Another ice age is due in about 80,000 years, and that will wipe out a lot of whatever little does survive. Africa will continue northward, turning the Alps into the next Himalayas. There won't be much, if anything that survives 65 million years of erosion and uplift. More important is what some far future intelligent species won't find. We are already pretty close to having used up resources that have accumulated over billions of years. In another 40 years, we'll be very, very close to having done so. That far future species won't find any readily accessible deposits of coal, or oil, or natural gas, or metals. Almost all of our iron ore originated from the Great Oxygenation Event, when iron dissolved in the oceans combined with the newly formed oxygen to become insoluble rust and settled to the bottoms of the oceans. Most of our coal, oil, and gas originated in the Carboniferous. That we had readily accessible resources is, to me, prima facie evidence that we are the first intelligent species on this planet. This is one of the reasons I'm dubious about finding intelligent life elsewhere in the universe. I suspect that a planet gets but one chance at forming a species intelligent enough to go into space. Once that species dies off, subsequent intelligent species won't find the resources needed to advance beyond stone age technology.
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Yes, he's an expert -- in the field of hoaxes, that is. Why do you fall for every bit of nonsense on the internet?
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Environmental modification, ENMOD and our changing climate
D H replied to subhumn's topic in Speculations
(1) You are moving the goalposts, and (2) I have already mentioned this twice now. I'll discuss it for the third time below. Where Sandy formed isn't on that map. It was a lot further east than Cuba. Discounting anthropogenic global warming as (unintentional) weather modification caused by billions of us, yes, your weather modification thesis is impossible. It is complete and utter nonsense. If you want something to blame for Sandy turning west rather than to the northeast, blame this: That blocking high over Greenland is what steered Sandy to the west. That blocking high typically does not exist at that time of year. Instead, there's a semi-permanent low over Iceland. Why did that happen? Perhaps you can blame this: That's the Arctic sea ice extent on September 16, 2012, the lowest level ever recorded. That same high pressure cell over Greenland was also responsible for drawing a lot of the ice in the Arctic south into the Atlantic. Which is cause and which is effect isn't known at this time. It might be that the very low sea ice extent was responsible for the creation of that blocking high. If that's the case, you might well be able to blame the following for making Sandy into the devastating storm that it was: Instead of just a handful of intentional conspirators, it might well have been billions of unknowing ones. -
The formula to solve n degree equation
D H replied to NaxAlpha's topic in Linear Algebra and Group Theory
There is no general purpose formula. There are order-specific techniques for linear, quadratic, cubic, and quartic equations, and that's it. The wikipedia pages on cubic and quartic equations show how to solve these equations. Warning: Cubic equations are a mess, quartics, even messier. That there is no general purpose formula for finding the roots of a fifth degree polynomial (or higher) is the result of Abel's impossibility theorem, one of the more celebrated theorems in mathematics. An alternative way to show that no formula is via Galois theory, a very important subject of abstract mathematics. -
Environmental modification, ENMOD and our changing climate
D H replied to subhumn's topic in Speculations
This is one huge load of horse excrement. Strike that, it is many, many loads. Conspiracy theories are so wonderful. They explain everything, and once we find the conspirators we can put them behind bars and be safe once again. If, on the other hand, things like Sandy are natural phenomena, well, we're never safe. Even worse, if the CO2 produced by 7 billion car driving, electricity consuming humans aggravates those natural phenomena, we're never, ever safe. Guess what: We're never safe. Sandy was a natural phenomenon, quite possibly aggravated by global warming. With regard to hurricanes not following the coast -- Nonsense. Here's a graph of hurricanes that came near Cape Hatteras, NC: Following the coast is exactly what many late season north Atlantic hurricanes do. It's rare to get a late season hurricane in the Gulf of Mexico because the steering currents tend to keep them out from the Gulf, driving them up the coast instead. Sandy was a pile of coincidences, but all natural coincidences. With regard to Sandy "being very fast for a hurricane" and "speeding up right before it hit New Jersey" -- Nonsense. That's what hurricanes do when they go subtropical: They speed up. It happens all the time. There are very sound meteorological reasons for this speed-up. With regard to Sandy moving "in a circle around New York City" -- Say what? I would have said "nonsense" again, but "nonsense" isn't the right word here. That's just not what Sandy did. It turned subtropical just about the same time it turned west. It kept going west for a bit, punching right through the stationary cold front that had been part of the steering currents that kept it just off the coast. After punching through, subtropical storm Sandy dropped a boatload of snow on West Virginia and Ohio, and then turned northeast. It did not move in a circle around New York City. With regard to Sandy turning west when hurricanes "usually head from west to east", first off, that isn't true. The worst kind of hurricanes, Cape Verde hurricanes, move from east to west. They form off of the coast of Africa, move west across the Atlantic, hit the Caribbeans or Florida, and from there either enter the Gulf or turn up the coast. You are talking about the behavior of tropical storms after they become post-tropical in the north Atlantic. Yes, they usually do turn to the northeast once the become sub-tropical. That's because of the prevailing steering currents in the north Atlantic. They weren't there for Sandy. A semi-permanent low pressure cell typically sets up over Iceland, and this low drives storms to the northeast once they reach the north Atlantic. That's not what happened with Sandy. Instead of the typical semi-permanent low over Iceland, there was a nice balmy very high pressure cell over Iceland. This steered Sandy to the west rather than the east once it went sub-tropical. For this to be a manufactured storm, the group behind it would have had to have made the jet stream form a cold front over the continental US that dipped down into Florida just as Sandy crossed Cuba. Then they would have had to somehow have made that cold front become stationary. Then they would have had to have somehow have to have steered Sandy right along the Gulf Stream. Then they would have had to have manufactured this high pressure system over Iceland. It's absolutely ridiculous. -
Environmental modification, ENMOD and our changing climate
D H replied to subhumn's topic in Speculations
Nonsense, both posts #1 and #2, but the opening post in particular. The first post is spam in the sense that the OP has posted this nonsense far and wide across the internet. It is also complete nonsense. Sandy was a late autumn Atlantic storm. These oftentimes track up the coast but then turn eastward thanks to a semi-permanent low pressure system in the northeast Atlantic. These late autumn tropical storms occasionally switch from being a tropical storm into a nor'easter. A double whammy, but still nothing particularly unusual yet. What made Sandy so unusual was that that low pressure system wasn't there. It was a high pressure system instead. Instead of turning the storm northeast and out to sea, it turned the storm to the west and straight for the coast. It was a natural phenomenon. To make matters worse, a cold front (another natural phenomenon) had formed off the Great Lakes just in time to feed Sandy even more. So, a quadruple whammy: hurricane plus nor'easter plus high pressure to the northeast plus cold front for a last bit of extra energy. All natural. As far as Sandy being caused by global warming, don't go there. The anti-global warming nuts use weird weather phenomena in the summer as supposed proof against global warming. Weird weather is just that, weird weather. It happens all the time. One incident of weird weather is neither proof of or proof against global warming. -
(Note: I fixed the link.) The link you provided talks about gravitation from a Newtonian mechanics perspective. Gravitation is instantaneous in Newtonian mechanics. Newton called this "action at a distance", and it bothered him greatly: That gravity should be innate, inherent, and essential to matter, so that one body may act upon another at a distance through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it. Yet despite Newton's objections to his own theory, this is precisely what Newton's universal law of gravitation does. The gravitational force between two objects in Newtonian mechanics is equal but opposite and depends on where the objects are "now" rather than where -- regardless of the distance between the objects. Physicists before Einstein investigated addressing the action at a distance problem by making gravitational potential energy depend on where the gravitating body was rather than where it is. There's a huge problem with this concept of a retarded potential: Orbits are no longer stable. Laplace calculated that the speed of gravity would have to be many million times that of the speed of light lest the solar system tear itself apart in short order. One cannot "fix" gravity just by making the potential (and hence force) depend on where things were rather than where things are. Between Laplace and Einstein, physicists investigated making gravitation work like electromagnetism (which is a lot more complex than just a retarded potential). That, too, didn't work. What did work is Einstein's general relativity. That's a lot more complex than is Maxwell's electromagnetism. When we are talking about the speed of gravity it is from the perspective of general relativity, or from the perspective one of the few remaining alternatives to general relativity that hasn't been ruled out by almost a century of tests of general relativity.
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Much better. It's important to distinguish (1) what we know from (2) what we think we know, from (3) what we think that we think we know, and of course from (∞) crackpot nonsense. That gravitational waves exist is pretty much fact, falling somewhere between (1) and (2), but much closer to (1) than (2). That they propagate at c is a solid (2). The distinction between (1) and (2) is perhaps hard to see from the perspective of theoreticians (such as you) who are solidly ensconced in category (3) (e.g., string theory). You left out what is perhaps the most important reference of all with regard to binary pulsars, Hulse, R. A. & Taylor, J. H., Discovery of a pulsar in a binary system, Ap.J. 195:L51-L53 (1975) http://adsabs.harvard.edu/abs/1975ApJ...195L..51H Most important because it was the first, and also because it won the 1993 Nobel Prize in Physics.
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We don't know that gravitational waves travel at the speed of light. We think (for very good reason) that this is the case. Physicists are, or should be, honorary Missourians: "Show me". Gravitational waves have yet to be detected. They are extremely hard to detect. Even if LIGO or some other experiment does detect them, assessing the speed is an even harder problem.
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Yes. It's coincidence + model errors + noisy measurements. The first error is their equation (1). This alone introduces a 1.3 second error in their "δ". (The annual solar aberration is about 20" of arc. At a rotation rate of 360 degrees per sidereal day, the Earth rotates through 20 arc seconds in about 1.3 seconds.) Coincidentally, that 1.3 second error is a whole lot less than the 8 minutes it takes light to travel from the Sun to the Earth. Coincidentally, the mean value of their δ, a lag of -0.9 seconds, is pretty close to what it should be (-1.3 seconds). However, this is just coincidence. Their measurements are so noisy (the δ values range from -18.2 to +36.6 for six measurements) that this -0.9 second lag is statistically indistinguishable not only from the correct -1.3 seconds but also from 0.0 seconds. (If their bad model was correct, the δ should have been 0). Suppose they had made better measurements. For example, suppose that their δ was -1.1±0.3 seconds instead of -0.9±22 seconds. The correct lag -1.3 seconds would still be within range but a lag of zero could be rejected. The final problem is the coincidence that 1.3 seconds is much less than 8 minutes. Their procedure for computing α, their supposed ratio of the speed of gravity to the speed of light, hides problems with their value of δ.
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Fixed that. Thanks. This new forum software bites. As for why this paper is so bad, the authors start off on a very bad footing by conflating gravitation and gravity waves. Then they go one step further into the excrement by looking at gravity waves emitted by the Sun as it orbits the Earth. To make matters even worse, their math starts with equation (1), which they label as the "practical Newtonian formula of solar tidal force." A better name for this would be "completely invalid formula of solar tidal force." This equation adds a lag to Newtonian gravity. You cannot just add a retarded potential to Newtonian gravity and be done with it. There's a whole lot more to general relativity than gravity propagating at the speed of light. Aside #1: Adding a lag to Newtonian gravity is a favored technique amongst crackpots for "disproving" general relativity because Newtonian gravity with a lag can easily shown to be invalid. However, this Newtonian gravity + lag model is but a straw man. It isn't general relativity. All these crackpots have shown is that this straw man is invalid. Aside #2: Tang KeYun, the principal author of the paper, is a crackpot of a different ilk. He's published a number of bad papers claiming to have seen the Allais effect. He apparently doesn't understand gravity or the Earth tides, which is sad for someone with a PhD in geophysics. Back to the paper, the authors proceed to make matters even worse with their equation (2). This adds a false model of the Earth tides to their already-invalid equation (1). To make matters worse still is the math they don't present, the mechanism by which they calculated the "phase lag due to the delayed response of anelastic Earth to solar tidal force." To make matters worse still, their equation (3) is fraught with error. A small value of δ with respect to ε is guaranteed to make ε/(ε+δ) close to one. Replace c, the speed of light, in ε=r*/c with the mechanical engineer's definition of c (the speed of sound in air at STP) and you get even better agreement than these authors obtained! In other words, they might as well have said that gravity propagates through vacuum at the speed of sound in air at STP.
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Nonsense. Citation needed, please. (Hint: You won't find one. "They" recently observed stars moving at a few percent of the speed of light around Sgr A*.) Nonsense. The only gobbling here is that this is gobbledegook. Here's the paper: http://link.springer.com/article/10.1007/s11434-012-5603-3 This is an open access journal; the PDF is freely available. This paper is 100% pure excrement. It starts off on a very, very bad footing (their equation (1) is complete crap) and then progressively gets worse and worse.
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Atoms cooled to negative degrees Kelvin for first time.
D H replied to Moontanman's topic in Science News
The headline is extremely misleading, "atoms colder than absolute zero". That's wrong. Negative temperatures are hotter than hot rather than colder than cold. The concept of negative temperatures arises from the thermodynamic definition of temperature, [latex]\frac 1 T = \frac{\partial S}{\partial E}[/latex] . Typically, entropy increases as energy is added to a system. What if the ground state is overpopulated? Now adding energy decreases entropy, making 1/T (and hence T) negative. This result has received a huge amount of hype. It's not new. It's older than me. E. M. Purcell and R. V. Pound, A Nuclear Spin System at Negative Temperature, Phys. Rev. 81, 279 - 280 (1951) -
Complete crap. Even worse, lots of arrogance and ignorance. I apparently broke things by typing the [ code ] ... [ /code ] tags manually. That apparently is a no-no; it breaks things. The bug report on this problem marks the bug this as "not a bug". Not a bug my rear end. It's a bug. Anything in the software that lets a user break things is a bug. The software must either handle manual tags or it must detect and reject them.
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You can use LaTeX to make some very pretty and professional looking tables via the tabular environment, you can't use that in the stripped-down version of LaTeX that is supported by this forum. What you can do is to use the array environment: [math]\begin{array}{ccc}\alpha&\beta& \alpha\supset\beta \\\hlineT&T&T \\T&F&F \\F&T&T \\F&F&T \\\end{array}[/math] [math] \begin{array}{ccc} \alpha&\beta& \alpha\supset\beta \\ \hline T&T&T \\ T&F&F \\ F&T&T \\ F&F&T \\ \end{array} [/math]
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In other words, you're trolling, and what's worse, you admit it.
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Since you described gravitation as being caused by the distortion of space time, you are speaking of gravity in a general relativistic sense. In general relativity, gravitation is a fictitious force. You can't feel any fictitious force, so you can't feel gravitation. As far as "acceleration is a fictitious force" goes, that makes no sense.