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That's not a correct image. There is only one groove on each side of a vinyl record, and it is a spiral. Orbits are elliptical, as described by Kepler, Newton and others. Some orbits are nearly circular (the earth around the sun), others are very elongated (comets).
http://en.wikipedia.org/wiki/Elliptic_orbit
That's not a correct image. There is only one groove on each side of a vinyl record, and it is a spiral. Orbits are elliptical, as described by Kepler, Newton and others. Some orbits are nearly circular (the earth around the sun), others are very elongated (comets).
http://en.wikipedia.org/wiki/Elliptic_orbit
In a perfect situation (point sized masses, no atmospheres, only two objects, no solar wind), the two objects would dance around each other essentially forever in a perfect ellipse (or a circle which is a special case of the ellipse) , and not decay. However, in the real universe, by coming close enough to encounter even tenuous atmosphere an orbiting object slows just a little bit each time it gets close and the orbit shrinks a little. Eventually the objects will collide. Other forces like the solar wind and additional objects in the neighborhood will affect the shape of the orbits and may eventually cause collisions or even fling an object out of the neighborhood. The system of objects may also settle down into a stable pattern for a very long time but nothing is forever. Forever is a very looong time and anything not forbidden is certain in the fullness of time and space.
Well, we only have about 1 billion years before the sun's luminosity increases to the point that all the earth's water evaporates into space, so get busy on that warp drive, will ya? Real space travel will not be possible until chemical rockets are looked upon with the same modernist disdain as horse-drawn carriages.
"Oh, look dear, a horse-drawn carriage. How quaint. Can we take it for a ride?"
"Horses smell, dear."
"Oh, look dear, an Atlas rocket. How quaint. Can we take it for a ride?"
"I'm not fond of their exhaust fumes either."
:lol:
The technical term is "chaotic system". If the planets' orbits were strictly Newtonian clockwork, you could look at their positions once and be able to predict where they'd be at any time in the past or future. In practice, things are slightly fuzzy, the best example being Pluto, due to a mathematical relationship between its orbit and Neptune's. If you follow it for more than a few million years, it will still be in the same orbit — probably — but almost definitely not on the predicted point on that orbit.
Things are even fuzzier when you go past a few hundred million or a billion or so years. The orbits themselves can pull at each other, shift and distort; there is evidence to suggest the outer planets might not have formed in the places we see them now. Beyond 5-10 billion years, it's a bit speculative. There probably won't be any collisions, and probably none of the current planets will be catapulted out of the system, but at this point prediction is pretty much impossible.
The space station is spinning in a particular direction so falling bodies must also fall in a particular direction, not straight down. This means that a yoyo will not behave the same on a spinning space station as it does on the Earth. Actually, the earth is spinning too, but it's not noticable as it would be on a space station that was spinning. The spinning space station uses centrifugal forces. Centrifugal force pulls bodies away from the center point of the space station but it is the structure of the space station itself (centripetal) that prevents bodies from continuing to fly off into space. The false gravity effect requires both the centrifugal and centripetal (friction) components to operate. You can only feel the fake gravity if you are in direct physical contact with the structure of the space station itself.
So lets assume that the station spins toward the direction in front of the juggler so that his torso points in the same direction as the ship rotates. When he initially releases the yoyo it will move straight upward and downward in its relative manner, but to us "stationary" observers the path of the yoyo will appear curved, such that it will arrive into the hands of the juggler a little farther behind where he would have expected it. So instead of landing in his hand it lands instead on his wrist or forearm. Basically, while the yoyo was floating in mid air the space station and the juggler were moving beneath it. The same should occur when he allows the yoyo to drop downward. When the yoyo starts returning upward it too will arrive in the juggler's clutch somewhere along his wrist or forearm because the juggler is in constant motion relative to the free falling yoyo.
Logistics. The wider the circumference of the torus at the end of the arms of the space station, the more powerful the centrifugal effect will be and the entire station spins at a slower speed than would be required for a smaller station to produce the same amount of centrifugal force. Realize that any ships that dock or take off from the station will also affect how fast the ship spins because of changes to the mass of the system, adjustments will need to be made every time a ship docks or takes off. The question is how big of an adjustment, and that is determined by the ratio of the mass of the station itself to that of the ship that is docking (as well as the directional vector the ship arrives or departs upon). Larger stations will have much more mass than any occupant of visiting ship being placed upon it and thus will be less affected by small changes in mass from ships arriving and departing. So for me this type of station begs to be large. If too small, the ship will spin much faster requiring more energy to maintain, it will be more sensitive to torque by changes in mass, plus residents of the ship will get sick due to tidal vertiao related issues, because their feet are experiencing much more gravity than their heads due to the feet being farther from the central spinning point than the head. With a large station the disparity between the g- forces at the heads and at the feet of the inhabitants becomes much more consistent and Earthlike.
How to shield radiation? You need lots of heavy water (deuterium). You could probably build a hull for the ship that contained thousands of gallons of frozen heavy water arranged in tiles. The tiles would be several feet thick. Also realize that the spinning station being made of metallic materials already will exhibit some degree of a magnetic field, its just a matter of polarizing it and boosting the magnetic field for long term space occupation.
One thing to keep in mind is that you cannot create a field without the particles needed to exhibit said field. You need magnetically charged particles to create a magnetic field. For a force field type shield effects we see on television , you need some form of physical matter to interact with incoming material. So if you imagine a space ship like the Enterprise, with its "shields" that seem to be able to physically deflect or vaporize incoming objects, realize that the field has mass because the field must be made of particles of some sort, likely electrons and other types of magnetically charged matter in the form of gas and plasmas. Still, it is likely the station would lose mass over time as some of the particles used for the force field would end up being lost to the vacuum of space. A shield would be very costly to maintain.
Biologically, things are odd from my assumptions. Males would be grounded I suspect. Our need to produce sperm on the go means there is too much likelihood for something to go wrong due to radiation exposure playing games during cell division processes. Females who already have their eggs in tact shortly after birth can store them in radiation proof containers if needed. Every night will be ladies night. Sperm would need to be stored separately and used only when the time was right for procreation. Other than sperm men serve no real purpose so it's unlikely they would be needed for long term space trips or on a station that was placed deep in space as a colony of sorts.
This is a fun subject to contemplate. Fun fun!
The spinning space ship design is not a new idea. It's called an "O'Neil Cylinder". I warn you, however, if you start reading wikipedia on this subject, you'll be tied up for hours. It's fascinating.
And no, things won't appear to fall "straight" down (aka "outward"). As something falls, the cylinder will continue its rotation, so the falling object may appear to fall in a non-linear line.
The same would occur in a centrifugal system. Objects would appear to fall downwards, as they would be accelerated by the rotation of the station.
They showed us a video shot from multiple cameras, two guys on a see-saw, throwing a ball back and forth. The ball traveled in a straight line between them, from their point of view. From the point of view of the platform the seesaw was on, the ball had more of an arc. From the point of view of the ground which could see the platform was spinning the ball not only had an arc from the up and down motion but also from the spinning motion of the platform.
A very interesting thread, thanks for starting it Misty (^_^)n...
... on the topic of toroidal spinning space stations and friction being required (to keep you moving along with the "floor")... does that imply that jumping would be a very dangerous activity? ergo no hopscotch for station children, unless you wanted to be pasted into the next bulkhead?
(thought experiment: from what I understand of what has been said above, you're standing on the inside surface of the space station being "thrown outward" by the centrifugal force, but being kept there by the "floor"... so if you break that contact eg by a little jump as you might do on Earth, you just float there (or drift slightly toward the nearest large gravitational mass, or carry on moving in the trajectory of your jump, like pushing off a wall in zero-g) until an internal wall inside the doughnut comes along, and *ouch* -- is this incorrect?).
I would guess ball games (eg soccer) would also be a challenge, to kick the ball "straight" at a goal in front of you... if the goalposts were lined along with the axis of rotation one side would have a massive advantage over the other... and if the goalposts were "cross-wise" from the rotation, then both sides would have to get used to kicking along curved trajectories?
Flipping pancakes in a frying pan in a station kitchen - also very tricky?
but, iz still just a theory if they don't actually test it in space?
what if a greater mass of celestial body goes by, will it pull the space station into it's orbit?
does a yoyo work on the real space station? that would be kewl to see.
i read an article they brought bees to the space station, the bees couldn't fly.
It is theory, but it is very well established theory. My physics is a bit rusty but I think relativity includes the principle of equivalence which says that the effects of gravity and acceleration are identical. The way it is usually explained is that if you were in a closed box and couldn't see outside, there is no measurement or experiment you can do inside the box to tell if the box is on a planet and gravity is holding you down or if the box is in space and accelerating constantly. "Centrifugal force" is really just the effect of the acceleration pulling you towards the hub instead of carrying on in a straight line away from the space station so it should have the same effect as standing on a planet.
The yoyo should work but it might be affected a bit by the coriolis effect. If an object that is stationary at the rim moves towards the hub it will be moving a bit faster than the objects around it since they are spinning round a slightly smaller circumference. So the yoyo might be deflected from side to side a bit as it went up and down.
As far as passing celestial objects are concerned, remember that the moon has about one sixth of Earth's gravity. To get a significant effect on the station you would need moon sized or bigger objects passing close to the Earth. Unlikely to happen outside of the sort of SF TV series where a nuclear explosion can send the moon out of orbit fast enough to visit a different star each week (not believable but fun to watch!).
Bees would have problems in the current space station since it is not rotating so has no centrifugal gravity substitute. If they ever manage to build a classic rotating space station then bees should be able to fly in it.
An object on the surface of the earth is moving at 1038 miles per hour, due to Earth's rotation.
The Earth is moving around the sun at a speed of 66,000 Miles per hour.
The Solar System is moving at 514495 Miles per hour around the center of the Milky Way.
And yet standing here on the surface of the planet we don't notice any of that. :) Balls fly straight, they don't curve, except the arc produced by gravity, etc.
Do I have to use non-Euclidean geometry to find out what a non-linear line is? :)
(I'm being silly. I know you meant 'path'.)
Once one has let go of a ball in a spinning space station it will appear to move outward (i.e. toward your feet) but it is no longer being accelerated by the space station via your feet through your torso to your hand to the ball. The ball is moving the same direction as you were at the moment you let go of the ball but is now moving at a constant velocity in a constant direction, whereas you are still moving with a varying velocity in a varying direction Moreover, your feet are changing velocity faster than your head. The ball as it "falls" toward your feet stays a constant velocity in a constant direction but from the point of view of your eyes it will appear to move in an arc. It will be moving at the velocity and direction that your hands had when it let go of the ball but your feet will move ahead of it (or behind it depending on which way you are facing) because your feet are moving faster.
This effect will be less noticeable the larger the radius of the space station because the percentage difference in velocity between your hand and feet will get smaller as the radius of the space station gets larger.
For example" consider a space station with radius of six feet, the height of a man, your head would be in the center of the space station your hand would be half way down and your feet would be all the way down. When you let the ball go from your hand it will start falling toward your feet but your feet will quickly change position and if the space station is moving fast enough you might be able to be upside down when the ball hits the "floor". However, the ball is not actually flying directly away from the center of the space station, it is moving tangential (90 degrees) to the circle made by your hand, not tangential to the circle made by your feet.
Consider the extreme situation where your space station is 3 feet in radius and you just comfortably fit across its entire 6 foot diameter. Your head is hitting the "ceiling" and your feet are hitting the "floor" and your hand is just below half way (so that there is some non-zero acceleration on the ball). If the space station is spinning at the proper rate and you let go of the ball it may start out appearing to move toward your feet but you may come around and get hit in the head with it!!! The ball would actually be moving in a straight line but would appear to you to move in an extreme curve. Ain't this fun???
This example is compelling, but I think misleading. If we consider the fulcrum of the see-saw as the center point of a spinning space station, we treat the see saw arms as the arms of space station, and of we consider the guys sitting on the seats to be the inhabitants occupying the the incomplete torus, then the issue is clear. The earthen example adds an additional parameter not present in open space.
Since this was a demonstration carried out on the planet Earth within Earth's gravity well, then there is an acceleration toward the "ground" which is affecting the ball and giving it a curve. On a space station, there is no curved space because there is no planet. Basically, the two guys on the ends of the seesaw are sitting at ground level but the ground they are sitting on is curved and will rise to meet the ball which is why they think the ball remains straight when in fact it does still curve. Basically, nothing about our daily experience of gravity as we feel it on Earth is relevant to a discussion about false gravity in the presence of no large gravitational bodies. Once you add something like a planet to the mix, its a whole different ball game and simulation lose validity.
And yet standing here on the surface of the planet we don't notice any of that. :) Balls fly straight, they don't curve, except the arc produced by gravity, etc.
Even Alex Rodriguez cannot toss a ball fast enough to reach speeds that are competitive with the speed of Earth's rotation, the speed of Earth's orbit about the sun, or the sun's orbit about the galactic center. And that is why we don't "see" the curve of falling bodies. It's a lot like time dilation, you can really only notice it when you get to speeds approaching that of light. It's not that time dilation doesn't always exist, its just not noticeable until it reaches extreme values.
The original query was about a yoyo, a device that has a string. That silly string is technically a tether connecting the spinning yoyo to the juggler and therefore to the space station. It is probably incorrect to assume the yoyo would fall if it were not for the string forcing it back down. This is MFM's question about free balls not connected by strings that begs a different explanation than a yoyo.
This example is compelling, but I think misleading. If we consider the fulcrum of the see-saw as the center point of a spinning space station, we treat the see saw arms as the arms of space station, and of we consider the guys sitting on the seats to be the inhabitants occupying the the incomplete torus, then the issue is clear. The earthen example adds an additional parameter not present in open space.
Since this was a demonstration carried out on the planet Earth within Earth's gravity well, then there is an acceleration toward the "ground" which is affecting the ball and giving it a curve. On a space station, there is no curved space because there is no planet. Basically, the two guys on the ends of the seesaw are sitting at ground level but the ground they are sitting on is curved and will rise to meet the ball which is why they think the ball remains straight when in fact it does still curve. Basically, nothing about our daily experience of gravity as we feel it on Earth is relevant to a discussion about false gravity in the presence of no large gravitational bodies. Once you add something like a planet to the mix, its a whole different ball game and simulation lose validity.
there is acceleration "downward," in fact if the space station is spinning properly it is exactly one gravity downward. The same rules apply F=MA regardless of whether that Force is generated by Gravity or by Centrifugal Force.
This example demonstrates the frames of reference section of Einstein's Theory of Relativity. And the frame of reference is very important.
For example if you are standing on the planet Earth and two men are throwing a ball back and forth the ball appears to be travelling in a For example you are sitting in a Baseball Stadium and Nolan Ryan (well in his prime, LOL) throws a fastball pitch, and the stadium is set up so the pitcher's mound is west of the home plate, then that ball is travelling at approximately 100 MPH. Note that at the short distance and the fast speed, Gravity has very little impact on the pitch.
If you are viewing that same pitch from L1, then the pitch is travelling West to East at 1138 MPH.
If you are viewing that same pitch from the North Pole then it is not only travelling at 1138 MPH but is also arcing along its path.
If you are watching the same pitch from the sun, then the ball is travelling between 64932 MPH and 67138 MPH. depending on the time of day.
It is all about your frame of reference and there is no one correct frame of reference. (One of the more complex parts of Einstein's Theory of Relativity.)
there is acceleration "downward," in fact if the space station is spinning properly it is exactly one gravity downward. The same rules apply F=MA regardless of whether that Force is generated by Gravity or by Centrifugal Force.
This example demonstrates the frames of reference section of Einstein's Theory of Relativity. And the frame of reference is very important.
For example if you are standing on the planet Earth and two men are throwing a ball back and forth the ball appears to be travelling in a For example you are sitting in a Baseball Stadium and Nolan Ryan (well in his prime, LOL) throws a fastball pitch, and the stadium is set up so the pitcher's mound is west of the home plate, then that ball is travelling at approximately 100 MPH. Note that at the short distance and the fast speed, Gravity has very little impact on the pitch.
If you are viewing that same pitch from L1, then the pitch is travelling West to East at 1138 MPH.
If you are viewing that same pitch from the North Pole then it is not only travelling at 1138 MPH but is also arcing along its path.
If you are watching the same pitch from the sun, then the ball is travelling between 64932 MPH and 67138 MPH. depending on the time of day.
It is all about your frame of reference and there is no one correct frame of reference. (One of the more complex parts of Einstein's Theory of Relativity.)
We don't disagree at all. I appreciate the difference you are sharing here. I guess I am saying that we have yet to determine a "preferred" reference frame for this thought experiment with the spinning space station, that is why I feel it necessary to qualify all of the current possible reference frames. While for some readers the experience of the juggler is important, to others it is the experience of the ball itself or of the space station. I agree, all three of these reference frames are different, and unless we focus the discussion on one particular reference frame we are required to describe all possible reference frames. That is why I go on about it as I do, attempting to cover all of the possible reference frames.
From the perspective of the ball itself, it will always think it is traveling in a straight line. All energy thinks its traveling in a straight line Outside observers however, will always view the ball's path as curved to some degree, to what degree it depends on the difference between the reference frames of the the ball itself and the observer. So yes, depending on whom you ask the path could appear to be straight or curved. However, I tend to think the balls opinion that it travels straight to be wrong, and the outside observer's opinion that the path is indeed curved to be the more correct viewpoint. But that's just me.
The main point I was trying to make is that once the space around an event has been curved, everything about the event changes because the frames of reference are skewed by the warped space. The experiment with the seesaw might look different without the presence of Earth's field. In flat Euclidean space, all reference frames are the same. If you only mean to describe energy in a still frame vacuum Euclidean units are okay. But if you want to describe events in time you need Cartesian specifications so that you can plot change over time.
And to take this to extremes, consider the point of view of a photon. A massless "particle" of light. It doesn't even experience time! So it has no notion of distance or direction either. It is born and dies in the same instant, and as far as it's concerned, the same place. Whether it travels from one atomic electron shell level to another, or 1 inch or across the entire universe it all happens instantaneously. A photon doesn't give a damn about time, space and the "speed of light", that's our burden. Us poor fat slobs with mass gummed up in the Higgs field. 8-s
Damn, I love this stuff!!!
And to take this to extremes, consider the point of view of a photon. A massless "particle" of light. It doesn't even experience time! So it has no notion of distance or direction either. It is born and dies in the same instant, and as far as it's concerned, the same place. Whether it travels from one atomic electron shell level to another, or 1 inch or across the entire universe it all happens instantaneously. A photon doesn't give a damn about time, space and the "speed of light", that's our burden. Us poor fat slobs with mass gummed up in the Higgs field. 8-s
Damn, I love this stuff!!!
I'm not so sure you can say that photons have no "notion" of time. A photon is created at some point in time, and its energy absorbed at some other point of time. There could be picoseconds between those events, or there could be billions of years between those events. The path of a photon can be altered by gravity alone (gravitational lensing). We also observe red shift if a light source is traveling away from our reference frame fast enough. The fact that the speed of light is finite, and it can be measured implies some notion of time. The fact that the speed of light is invariant regardless of reference frame has all sorts of interesting consequences, tho.
I'm not so sure you can say that photons have no "notion" of time. A photon is created at some point in time, and its energy absorbed at some other point of time. There could be picoseconds between those events, or there could be billions of years between those events. The path of a photon can be altered by gravity alone (gravitational lensing). We also observe red shift if a light source is traveling away from our reference frame fast enough. The fact that the speed of light is finite, and it can be measured implies some notion of time. The fact that the speed of light is invariant regardless of reference frame has all sorts of interesting consequences, tho.
Please don't think that I'm arguing. I've agreed with most everything that's been said in this thread. I'm just trying to make sure that I carefully say what I meant to say about my take on these subjects.
I apologize for diverting us into quantum physics but the idea of seeing things differently from different points of view was my entry point. All things are relative. I just took it to the extreme.
Regarding what you mentioned about photons is correct but it is from our point of view of the photon. The photon itself is outside of time. If we see it as travelling at the speed of light then the equations say that from it's point of view it gets from point A to point B in zero time. Or maybe it's easier to consider the photon exists in a higher dimension where time is irrelevant and what we see of the photon is only a projection or shadow of the photon. Same thing for all massless particles. It's only massy particles that experience space and time. The massy particles essentially "create" spacetime because they're enmeshed within the Higgs field and their projections into 3 dimensions are "stuck".
Massless particles like the photon (from our point of view) have only one speed. The speed of light. If we had a machine that could turn off the Higgs field within an object, the object would instantly fly apart at the speed of light probably in a massive explosion of energy.
Pondering and researching "Why is there a limit to the speed of light?" helped me break out of the trap of thinking of space and time and instead trying to envision a more telling concept "What gives rise to spacetime"?
Considering the very real phenomenon of Quantum Entanglement one needs to consider that the wave that is a photon actually exists everywhere in the universe simultaneously, which quantum mechanics hints at, and which is not impossible if you're in a higher dimension outside of time and space. Spooky action at a distance is no mystery if the entangled photons experience no time dimension. Spacetime is a subset of higher dimensions of reality.
I've thought and read seriously about these things for at least 45 years. I'm beginning to see through the haze. The puzzle pieces are falling into place. I'm not a mathematician and I'm trying to explain my view of the nearly unexplainable, in words only. So take my words with a grain of salt and pick what you can from it.
This would all be voodoo or gobbledy-gook if it weren't for the fact that these ideas are seriously researched by top scientists and in some cases verified and used to produce real and useful technologies. The complete explanation doesn't exist yet. But what we do have is very very useful. Admittedly, wrapping one's head around these ideas can be confusing. Mathematics is one way to see some of these things. As time goes on and more and more of these ideas filter down into more and more people, it becomes easier to wrench ourselves out of the limitations of thinking about space and time as separate and immutable.
Where we as conscious beings fit into this framework is for each person to decide for themselves.
"There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy." Hamlet, scene v
-- William Shakespeare --
OK, back to our favorite space station. Let's say I'm standing on the inside surface of this wheel or barrel that is spinning to simulate something close to 1G. Let's say I'm standing facing backwards wrt to the direction of rotation. Let's say I'm holding a bowling ball directly over my toe. If I release it, the bowling ball will land in front of my toe, not on my toe because my toe's linear velocity was higher than that of the bowling ball? That would make a very popular bar bet in the space station cantina! :lol:
BTW, objects do not always travel in straight lines. In the absence of any gravitational field, they will, according to Newton's laws. In the presence of gravity, objects exhibit ballistic trajectories. As any pirate will tell you, cannon balls fly in a curved path. That's why they're called ballistic trajectories. The horizontal component of a cannon ball's trajectory is nearly constant, but decreases due to air resistance. Once it leaves the muzzle, the horizontal velocity does not increase. The vertical component of it's velocity changes over time. The downward motion of the cannon ball will increase with the square of the flight time, until it hits something. It's a parabola, at least without air drag. With air drag, computing the actual trajectory is a real drag...
http://en.wikipedia.org/wiki/Trajectory_of_a_projectile
Especially since whether or not it works depends on which way round you're standing — if you talk someone else into turning the other way round, towards the direction of rotation... I think you'll win the bet. ;-)
(Will there be an "eeeeeeeeeeeevil grin" smiley in the new forum?)
I'm not so sure you can say that photons have no "notion" of time. A photon is created at some point in time, and its energy absorbed at some other point of time. There could be picoseconds between those events, or there could be billions of years between those events. The path of a photon can be altered by gravity alone (gravitational lensing). We also observe red shift if a light source is traveling away from our reference frame fast enough. The fact that the speed of light is finite, and it can be measured implies some notion of time. The fact that the speed of light is invariant regardless of reference frame has all sorts of interesting consequences, tho.
In my opinion you are both making valid points. But again, we need to be more specific about the terms we are utilizing if we are keep everyone involved to the level we want. We need to be specific about what we mean when we say time and when we say space and when we say momentum.
There are at least two different types of "time." This is the reason why Einstein required two relativity theories instead of just one.
Special Relativity could be described as the first person experience of an event. These equations describe the way information transfer between two bodies is affected by the speed and direction by which they move through empty space in relation to one another. It's not my absolute momentum and direction of movement that matters, it is my momentum and direction of movement relative to the other guy who's trying to send me a signal that matters. It's an A/B conversation type of thing. SR explains why distant galaxies color spectrums are red shifting relative to us and our direction and speed of "movement." It tells us how to correct for the distortion of the information we received from the other guy.
General Relativity by contrast, describes time in the third person, the way things look from an outside observer. An A/B + C type of conversation. General Relativity describes space and matter in geometric terms. GR explains why the pathways of light rays are bent by the presence of gravitational fields, SR does not deal with this. at least not directly. GR tends to more accurately describe situations where SR becomes incomplete.
SR and GR both demonstrate that time and space are linked from a first person experience standpoint, and that the more you travel though one the less you travel through the other. The faster you travel through open space, the less you travel through time and the less "generalized" and more "specialized" your relativity becomes.
Photons travel at the physical speed limit of C, which means they are traveling so fast through space that they cannot travel at all through time from a special relativity standpoint. The photon never even realizes it exists, it is created and destroyed before it can become aware of itself. From a GR third person observer standpoint however, time is still ticking and the photon might fly through space for billions of years before colliding with something else, all the while its path is being bent from interacting with various gravitational fields. But that doesn't change the fact that from an SR view the photon itself has experienced no time since it's creation to its destruction.
Time passes more slowly on the Earth's surface than it does on satellites orbiting in space, because on Earth you are at the bottom of the gravity well. The space around you is moving very fast accelerating you downward keeping you firmly planted on the surface. That is why warped space is treated as a type of momentum in these discussions, thus bridging the gap between SR and GR descriptions of falling body events.
Where SR and GR both are needed is in situations where it is the gravitational warping of space (not the fixed value of C) which is the reason for the acceleration that gives rise to the SR. Best example is the Event Horizon of a black hole. At such an extreme point in space, material is being pulled into the star by the extremely curved space around it, so much so that two important things occur;
1. Spagettification: items are pulled apart, literally ripped to shreds by the tidal forces creating an effect known as spagettification. Just like the example in the spinning station where the force at one's feet is greater than at one's head. At the event horizon of a black hole even the smallest distances can have huge variation in total force. If you were to stand on the event horizon your feet would be pulled in with millions of times more force than at your head which would pull you apart , even ripping apart the individual atoms
2. At the event horizon your momentum gets so close to C that your special relativity approaches that of a photon where your first person experience of time drops to nearly 0 even though from a third person standpoint time is still progressing.
It could be argued that there is a third type of time, treated as an absolute time. This is the type of time used to describe the universe and its evolution from the big bang to the present day. In absolute time (which is probably more of an extension of GR) says that the universe is expanding over "time." This expansion is not a mere "perceived" effect in the way SR is merely a perception or distortion, this is the real deal. We know this because there are both SR and GR related artifacts that tell us the expansion is real.
First we need to understand that there is nothing for the universe to expand into. There is no infinite arena of empty space surrounding the universe. If you step off one edge of the universe your foot lands on the opposite side of the universe, there is no way to ever go outside of the universe. What we need to realize is that the universe itself is growing, or better stated, that the empty space itself is growing, making items appear to move away from one another when in truth objects aren't really moving at all, its just the amount of space in between things is increasing exponentially over time. As space grows, so does time itself (that's why time has an arrow and backward time travel is impossible). You cannot travel back to a time when the universe was smaller than it is now, and you can only travel into the future at the speed the universe expands. Time travel forward and back would be much easier in a static universe.
Einstein made a statement once about time saying that it was exactly like space. He said that the future is already there, all we need to do is to displace ourselves in time to reach that point. He then likened it to space, saying that Singapore is already there and that all I have to do is to displace myself in space to reach the point where Singapore is located. But this was back when Einstein like most everyone else thought that the universe was static, unchanging in scale over time. Now however with the advent of Hubble, we know that the universe is not static and that the universe is not the same today as it was yesterday, its bigger than it was yesterday and cooler too. Objects that were once close in spacial proximity are now far apart in spacial proximity. Same with time. futures don't exist until the space they will exist within has been created by the expansion of the universe. Getting to Singapore seemed easy enough when we thought it was stationary, but now re realize that Singapore is a moving target and it is impossible to predict exactly where the target will end up, limiting our ability to travel very far into the future. We are forced physically to "wait and see."
This expansion has recently been termed as Dark Energy, as it seems to cause the universe to expand thinning out the radiation emitted by magnetically charged (light energy) particles.
The real mystery here isn't the behavior of matter, it is this thing we erroneously call empty space. Space is not a passive entity, no indeed, it is the director of all traffic.
this has gotten very deep and still nobody has built a cool spinning fully equipped space station for DAZ.
bits of ones do not count, you reading this Stonemason? Get those vertices plotting while I save up.
Agreed — I won't even mind much if it's unrealistically small, like the carousel aboard the Discovery in 2001.
Most of the actual proposed ideas are just a little bit bigger (Stanford torus, a mile across; Bernal sphere, 16km wide; Island One, 500m wide, Island Three, twin cylinders 5 miles x 20 miles). Don't try this at home unless you have a major film studio's render farm in your spare room...
Here's an example of what a space station looked like in the '50s. The thing on the top is the docking tower, complete with magnetic beams to pull in the spaceships that always looked like the inside of a three room mobile home and always looked horizontally arranged even when standing vertical on the launch pad! (I caught that flaw when I was 7 years old!)
We didn't get to see much of the space station except exterior shots. They had an interior set for the space station communication room and I think I saw one other room and a straight hallway once.
Space station from "Rocky Jones: Space Ranger" TV series in the 1950s
Check out the communication device in Rocky's hand. A microphone attached with a wire (how quaint). It looks like an eggplant. Perhaps Apple could make it wireless and call it the "iEggplant".
I was trying to find a specific MythBusters video that was somewhat if not very applicable to the notion expressed above, but haven't been able to find it yet.
However, I thought you guys might enjoy this MythBusters video on Relative Motion/Velocity... https://www.youtube.com/watch?v=BLuI118nhzc
*wink*
As for the idea of using Centrifugal Force to simulate gravity in a zero gravity environment (outer space)... I find it hard to believe some astronaut hasn't at some time tried holding one end of a string, wire, rope, or chain, perhaps with some form of weight on its opposite end, and tried spinning it around in a zero gravity environment. Dog tags would certainly work for this experiment. This would prove that Centrifugal Force works just as well in zero gravity as it does within a gravity rich environment.
I was trying to find a specific MythBusters video that was somewhat if not very applicable to the notion expressed above, but haven't been able to find it yet.
However, I thought you guys might enjoy this MythBusters video on Relative Motion/Velocity... https://www.youtube.com/watch?v=BLuI118nhzc
*wink*
As for the idea of using Centrifugal Force to simulate gravity in a zero gravity environment (outer space)... I find it hard to believe some astronaut hasn't at some time tried holding one end of a string, wire, rope, or chain, perhaps with some form of weight on its opposite end, and tried spinning it around in a zero gravity environment. Dog tags would certainly work for this experiment. This would prove that Centrifugal Force works just as well in zero gravity as it does within a gravity rich environment.
The only difference being that in this video the ground itself isn't moving, nor is the camera that has been placed onto the ground. On the space station the ground and the camera fixed on it would be moving.
I was trying to find a specific MythBusters video that was somewhat if not very applicable to the notion expressed above, but haven't been able to find it yet.
However, I thought you guys might enjoy this MythBusters video on Relative Motion/Velocity... https://www.youtube.com/watch?v=BLuI118nhzc
*wink*
As for the idea of using Centrifugal Force to simulate gravity in a zero gravity environment (outer space)... I find it hard to believe some astronaut hasn't at some time tried holding one end of a string, wire, rope, or chain, perhaps with some form of weight on its opposite end, and tried spinning it around in a zero gravity environment. Dog tags would certainly work for this experiment. This would prove that Centrifugal Force works just as well in zero gravity as it does within a gravity rich environment.
Though the astronaut would of course also oscillate as a result, unless anchored.
Though the astronaut would of course also oscillate as a result, unless anchored.
Oscillation is exactly right.
Obviously... I just didn't think it needed to be said.... but I guess it did. :-)