TranceAddict Forums (www.tranceaddict.com/forums)
- Political Discussion / Debate
-- physics anyone?
Pages (3): [1] 2 3 »

physics anyone?

dont think this is the proper forum for a question on physics but i rather post it here than the chill out room and get stupid answers. i was reading stephen hawkings book"a breif history of time" and came across the idea of relativity and the so called "twins paradox" where one twin stays on earth the other jets into space. when the other twin returns he is significantly younger. but why? has anyone taken physics courses? or just knows how to explain it? thanks in advance

Re: physics anyone?

quote:

Originally posted by hiram dont think this is the proper forum for a question on physics but i rather post it here than the chill out room and get stupid answers. i was reading stephen hawkings book"a breif history of time" and came across the idea of relativity and the so called "twins paradox" where one twin stays on earth the other jets into space. when the other twin returns he is significantly younger. but why? has anyone taken physics courses? or just knows how to explain it? thanks in advance

This is a very appropriate forum to pose such questions and it usually leads to the most intriguing threads here (Drug_tito is usually the last person to post in such threads with the definitive answer). Time dilation (the principal theory behind the twins paradox) is one of the most difficult topics to simplify however, and I don't think I can do a good job of it. As best as I can do it, time dilation rests upon the theory that time becomes a relative measure that is in a certain way derived from the doppler effect and the speed of light. I understand the physics behind it but simplifying it into layman's terms only raises doubts as to whether I truly understand the concept. I'm going to to have to do more research, unfortunately I'm off to bed soon so I'll try to answer your question tomorrow!

I'm not sure if you want a more simplified answer than this, but I think it should help:

quote:

The resolution of the Paradox in special relativity The usual resolution of the paradox as presented in physics text books ignores its origin (it only surfaced with general relativity, see above) and regards it as a problem due to misunderstanding of special relativity. Here the Earth and the ship are not in a symmetrical relationship: the ship has a "turnaround" in which it feels inertial forces, while the Earth has no such turnaround. Since there is no symmetry, it is not paradoxical if one twin is younger than the other. Nevertheless it is still useful to show that special relativity is self-consistent, and how the calculation is done from the standpoint of the traveling twin. Of course the traveling twin comes home younger. Special relativity does not say that all observers are equivalent, only that all observers in inertial reference frames are equivalent. But the space ship jumps frames (accelerates) when it does a U-turn. The twin on Earth rests in the same inertial frame for the whole duration of the flight (no accelerating or decelerating forces apply to him) and he is therefore able to distinguish himself as "privileged" compared with the space ship twin. The accepted resolution of the paradox is that the crew must make a different calculation from that above, a calculation which explicitly recognizes the change of reference frame, and the change in simultaneity which occurs at the turnaround. There are indeed not two but three relevant inertial frames: the one in which the stay-at-home twin remains at rest, the one in which the traveling twin is at rest on his outward trip, and the one in which he is at rest on his way home. It is during the acceleration at the U-turn that the traveling twin switches frames. That's when he must adjust the calculated age of the twin at rest. Here's why. In special relativity there is no concept of absolute present. A present is defined as a set of events that are simultaneous from the point of view of a given observer. The notion of simultaneity depends on the frame of reference (see relativity of simultaneity), so switching between frames requires an adjustment in the definition of the present. If one imagines a present as a (three-dimensional) simultaneity plane in Minkowski space, then switching frames results in changing the inclination of the plane. In the spacetime diagram on the right, the first twin's lifeline coincides with the vertical axis (his position is constant in space, moving only in time). On the first leg of the trip, the second twin moves to the right (black sloped line); and on the second leg, back to the left. Blue lines show the planes of simultaneity for the traveling twin during the first leg of the journey; red lines, during the second leg. Just before turnover, the traveling twin calculates the age of the resting twin by measuring the interval along the vertical axis from the origin to the upper blue line. Just after turnover, if he recalculates, he'll measure the interval from the origin to the lower red line. In a sense, during the U-turn the plane of simultaneity jumps from blue to red and very quickly sweeps over a large segment of the lifeline of the resting twin. The resting twin has suddenly "aged" very fast, in the reckoning of the traveling twin.

Wikipedia: Twins Paradox

Re: Re: physics anyone?

quote:

Originally posted by occrider This is a very appropriate forum to pose such questions and it usually leads to the most intriguing threads here.

I still think that this forum is mislabeled. It should have been called Philosophy, Politics, and Religion. There's been several threads that starts out with an apology for even posting non-political stuff. Think of all the good threads that might have been killed in its infacy because of such self-censorship.

They already tried this, and it works.

One twin went into space, and the other stayed. I believe the one going into space was OLDER than his brother on earth, probobly by a couple of minutes. Well, the twin came back, and somehow they figured and calculated that the twin on earth was something like .003 seconds older than his twin. How does that work? I dunno, and I am not googling this.

look up "Special Relativity". It all ties into the theory that as an object approaches the speed of light, its mass approaches infinity, as it's size compresses to near zero. It's complicated and I'm clearly not explaining anything. Basically, as things approach the speed of light, crazy shit starts to happen. That's why you need a flux capacitor.

http://en.wikipedia.org/wiki/Special_relativity

http://en.wikipedia.org/wiki/Twins_paradox

quote:

Originally posted by Shakka look up "Special Relativity". It all ties into the theory that as an object approaches the speed of light, its mass approaches infinity, as it's size compresses to near zero. It's complicated and I'm clearly not explaining anything. Basically, as things approach the speed of light, crazy shit starts to happen. That's why you need a flux capacitor. http://en.wikipedia.org/wiki/Special_relativity http://en.wikipedia.org/wiki/Twins_paradox

yeah i did read about particle accelerators and never being able to get particles past the speed of light no matter how much energy was put in. and thanks Shaolin_Z that kind of helped a bit. i saw that same drawing last night when i googled it but couldnt wrap my mind around it. things are abit more clear now

Re: Re: Re: physics anyone?

quote:

Originally posted by trancaholic I still think that this forum is mislabeled. It should have been called Philosophy, Politics, and Religion. There's been several threads that starts out with an apology for even posting non-political stuff. Think of all the good threads that might have been killed in its infacy because of such self-censorship.

The last guy that wanted to rename the forum got his thread closed. I am not going to mention any names but if you point I'll whistle.

Don't know much about Physics at the moment but it's stuff like this that interests me about it.

My uncle teaches Physics overseas so i hope to go over there and learn and get a degree hopefully. Yes i know this didn't have any relevence to the thread hehe.

I might be wrong but wouldn't it be likely due to how time is slowed down in a space contingent?

Re: Re: Re: Re: physics anyone?

quote:

Originally posted by ogvh5150 The last guy that wanted to rename the forum got his thread closed. I am not going to mention any names but if you point I'll whistle.

Heh, yeah, although his renaming idea was a bit retarded. Anyway, I agree that it might be a good idea to rename the forum. Anyone up for signing up a petition to Wicked Neo? I'd kinda like to add science into the title too.

Anyway, about the twins paradox. Basically as someone said earlier, the reason why this happens is time dilation. When you're approaching the speed of light time in your reference frame flows slower than it does in a fixed frame from which you originated. Therefore for the travelling twin the trip seemed to be much shorter than it did for the stationary twin.

The reason why this happens is because time is not flowing everywhere at a constant pace. The only thing that always does remain a constant is the speed of light. In other words, both the traveling twin and the stationary twin will see light beams sent from each other and travelling past each other travel at exactly the same speed. The only way to achieve this is to change the speed at which time is flowing. In other words, say a stationary guy sees a light beam travel past him towards his moving twin at the speed of light. For him the time that it will take the light beam to reach the other twin will be the time needed for the speed of light to travel the original distance + the times it will need to travel additional distances by which the twin moved away during the times light came to his position. Now, if the time flow was the same for both, for him the light beam should seem to travel slower since he is moving away from the stationary twin.

But, because of the wierd nature of the universe, the light beam is flying towards him at exactly the same speed at which the stationary guys sees it moving away from him. So for him, the only distance light has to travel is the distance that was between the twins at the moments the light beam was emitted. So since we have beams that are travelling at same speeds over different distances, the only possible scenario to achieve this is that the time on the ship and the time on the ground flow at different speeds.

quote:

Originally posted by Marc Summers They already tried this, and it works. One twin went into space, and the other stayed. I believe the one going into space was OLDER than his brother on earth, probobly by a couple of minutes. Well, the twin came back, and somehow they figured and calculated that the twin on earth was something like .003 seconds older than his twin. How does that work? I dunno, and I am not googling this.

Well, it wasn't two people, but they did have "twin" super-accurate clocks for an experiment such as that. They allowed one clock to orbit the Earth (for us Earthlings, that pretty much as fast as we get, unless you're traveling to another planet), while another "reference" clock stayed on the ground. After a fixed amount of time for the reference clock on Earth they compared the two and found there was a difference.

Here's a pretty neat webpage that puts some of the more modern views of space time into at least potentially digestable form.

http://casa.colorado.edu/~ajsh/home.html

Yea here was the aircraft experiment:

quote:

The Elasticity of Time By Daniel Siegel In December of 1923 a pierce of doggerel appeared in Punch, poking fun at Albert Einstein's newly famous theory of relativity: There once was a lady named Bright, Who traveled faster than light. She set out one day, In a relative way, And returned on the previous night. The piece was unsigned, but years later A.H. Reginald Buller stepped forward to claim authorship. He was a fellow of the Royal Society of Canada and came from a different field of science: he was editor of the seven-volume Researches in Fungi. In the early years, experimental support for relativity theory was meager: full vindication of Albert Einstein's ideas was still to come. Relativity theory had drawn startling conclusions concerning the four most basic physical quantities-length, time, mass, and energy. In the course of the century, these results would receive direct and very striking experimental confirmation. The relativistic effects also became the basis for new technologies, such as Global Positioning Systems (GPS), whose continued functioning would verify these effects every day and every passing hour. The disruption of time was the most fundamental conclusion. Both in Einstein's technical paper of 1905 and in Relativity Clear and Simple, the relativity of simultaneity formed the basis for all subsequent discussion. In particular, Einstein showed that moving clocks as compared with stationary clocks would run slow as a result of their motion. As Einstein was philosophically committed to the idea that time was nothing more nor less than what you could measure with standardized clocks, he necessarily concluded that time itself passed more slowly in a moving frame of reference and the faster the motion of the reference frame, the slower the passage of time. Background, collage on the relativity of time; inset, Einstein's written notes on the theory of relativity; left, Einstein in 1905, the year his theory was published. This was called time dilation: time slows down, stretches out, dilates, in a moving reference frame. This was the most revolutionary conclusion of relativity theory. It was also, for a period of more than thirty years, completely unsupported by any direct experimental evidence. Critics of relativity theory, of course, jumped on Einstein: Wasn't it ridiculous to make the claim--on the basis of no direct evidence whatsoever--that time itself could slow down? And wouldn't various paradoxes and absurdities result from this kind of elasticity of time? Would an astronaut who traveled in a rocket ship at high velocity age less than his twin who stayed at home? If time could slow down as a result of motion at high speed, would time reverse if one went fast enough? Discussion of time dilation left the realm of the fanciful when it became possible to verify this effect in a direct manner. This first occurred in 1941, when time dilation was detected in experiments on cosmic rays. The earth is continually bombarded by atomic particles from outer space. These swiftly moving particles are the "primary" cosmic rays. When the particles reach the top of the atmosphere, they collide with atomic nuclei. Subatomic debris is produced, constituting the "secondary" cosmic rays, which then travel downward toward the surface of the earth. In particular, particles called muons are produced in the upper atmosphere and move downward toward the surface. Muons are highly unstable particles, having an average lifetime of about a millionth of a second. Given the short lifetimes of the muons and the long distances they have to travel to get down to the surface of the earth, one can calculate that, given the velocities at which they travel, very few of them should actually make it down to sea level. However, large numbers can be detected- many more than expected. It appears that, somehow, the moving muons have longer lifetimes than expected, so that they can travel longer distances than expected. This is exactly what would be expected on the basis of time dilation. The muons are traveling at velocities comparable to the velocity of light, and their internal "clocks" should slow down as a result--in accordance with Einstein's prediction--so that many more are able to reach the surface of the earth than would be otherwise expected. Precise experiments on muons gave results exactly in accord with Einstein's equation for time dilation, verifying the effect quite convincingly. In the years after World War II, experiments on unstable elementary particles such as muons were carried out by using high-voltage particle accelerators to produce beams of the particles. The time dilation equation was again verified to high precision, and the experimental technologies used in particle physics have come to rely on time dilation for their successful day-to-day operation. For those who are not particle physicists, verification of time dilation has become possible with the development of a device known as an atomic clock, which can measure time intervals to a precision of one part in a trillion. Consider flying in an airplane at five hundred miles per hour. This produces minimal time dilation, and air travelers have not noticed their watches running slow as a result of this effect. Calculations on the basis of Einstein's equation for the time dilation, however, show that the expected effort is a slowing down by about one part in a trillion, which should be measurable by an atomic clock. In 1971, a team of scientists who were experts in the use of atomic clocks set out to detect and measure time dilation and other relativistic effects. The research team was able to devise a cheap and effective plan, which received some support from the Office of Naval Research. We are told that the researchers purchased three around-the-world tickets on regularly scheduled commercial airliners-two tickets for the accompanying scientists and one for an array of four atomic clocks. The clock array had its own seat; it sat, belted in for safety, between its two caretakers. Before leaving on the trip, the clocks were synchronized with a master clock at the U.S. Naval Observatory. The four clocks then went around the world, following which they were compared again with their counterpart, which had stayed behind at the Naval Observatory. After correcting for the rotation of the earth and the variation of the force of gravity with altitude, it was found that the clocks that had been in motion in their journey around the earth had in fact slowed as compared with the clock at the Naval Observatory, and by exactly the amount predicted by the theory of relativity. The result was further confirmed in a second around-the-world flight in the opposite direction. The effect of this exercise on the scientific community was more to demonstrate the capabilities of atomic clocks than to make any substantive change in the way scientists regarded the theory of relativity, but the result was nevertheless satisfying: it was the most direct possible realization of Einstein's thinking about measuring time with real, physical, standard clocks. The clocks had behaved exactly as Einstein had predicted they would. These days, when atomic clocks are transported by air from Washington, D.C., to Boulder, Colorado, as part of the regular maintenance of the United States time standard, corrections are made for the time dilation based on a log of the flight with records of ground speed and elapsed time. Similarly, in the satellitebased GPS that represents the current state of the art in navigation, corrections are made for the effect of time dilation on the atomic clocks orbiting in satellites whose time signals form the basis for the system. If time dilation were somehow turned off, not only would particle physics experiments shut down, but the most advanced navigational systems for both military and civilian needs would fail to operate. Aircraft and missiles, ships and submarines, trucks and trains, and hikers and hunters with their consumer-market GPS systems would literally lose their bearings. In the new millennium both science and technology have come to depend at every passing moment on the particulars of the behavior of time as specified in the theory of relativity. http://www.neh.gov/news/humanities/...elasticity.html

I could learn to call this place the PPR.

Here's an interesting tidbit from wikipedia...

quote:

The Global Positioning System can be considered a continuously operating experiment in both special and general relativity. The on-orbit clocks are corrected for both special and general relativistic time-dilation effects so they appear to run at the same (average) rate as clocks at the surface of the Earth. In addition, but not directly time-dilation related, general relativistic correction terms are built into the model of motion that the satellites broadcast to receivers -- uncorrected, these eccentric terms would amount to a 12-hour, approximately 7 metre, oscillation in the pseudo-ranges measured by a receiver.

So what would happen to time in the limiting case, if one were travelling at the speed of light?

quote:

Originally posted by HardTranceProd So what would happen to time in the limiting case, if one were travelling at the speed of light?

According the formula:



If you would put in a speed equal to speed of light there it would be to divide by zero which is impossible, so it can't happen. Someone else might have a better explanation though

If I had only known, I would have been a locksmith
Albert Einstein

quote:

Originally posted by HardTranceProd So what would happen to time in the limiting case, if one were travelling at the speed of light?

You'd be there and back in a split second while for the rest of the world you'd be travelling at the speed of light. The faster you travel the faster the events in the universe around you seem. I suppose if you'd reach the speed of light, universe around you would start to unveil at an infinite speed. So I guess you'd end up being everywhen at once. Now, unless the equations are flawed or incomplete, if you'd travel even faster I guess you'd start travelling through a timeline perpendicular to ours, whatever that might mean.

I thought, if you travelled at the speed of light, then time dilation would be so extreme that time would hold still. And then, if you exceeded the speed of light (impossible of course), you would go back in time (into the past).

quote:

Originally posted by HardTranceProd I thought, if you travelled at the speed of light, then time dilation would be so extreme that time would hold still. And then, if you exceeded the speed of light (impossible of course), you would go back in time (into the past).

Yup, they proved that in Star Trek IV. Used the sling-shot effect around the sun. That's how they saved the whales.

In Spaceballs, they simply went plaid.


It's actually an interesting question that I never got satisfactory answers for back in physics classes. On one hand, I was told that there was "dark matter" out there that moves around faster than the speed of light. On the other hand, I was told that the speed of light was an asymptote/limit and that according to the numbers, it was therefore not even possible to reach said speed. (all the while recognizing that the speed of light certainly isn't a theoretical limit for light itself, rather it is essentially an absolute!) So in essence, all I could do was theorize about what could possibly happen. Since time was supposed to slow down, relatively speaking, as one approaches C, the logical conclusion would be for time to stop at C, and possibly reverse at a velocity greater than C, thus explaining theoretical time travel. Or something like that.

As far as never being able to achieve C, my understanding was that if thought about incrementally, at the margin if you will, each additional increment of speed/acceleration would require an additional amount of energy to get the incremental push to reach the faster speed. In essense, since C represents an asymptote, the incremental amount of energy needed would approach infinity, therefore rendering getting to C absolutely impossible. Go figure. Mind blowing stuff to try to comprehend.

Of course, in a perfect vacuum, with an infinite amount of space, I'd think that Newton's first law could be taken a step further to say that an accelerating object in motion will continue to accelerate unless acted upon by an external force, which not only would allow it to reach the speed of light, but also to theoretically go beyond it since nothing would slow it's accleration. But of course I'm sure I'm wrong about that. Maybe the object would burn up before it could reach C. Shit, I give up.

My dumb way of explaining it:

Imagine a box which you trap a beam of light in and it bounces off mirrors (perfect ones..) at the top and bottom of a box. Just goes up and down.

In 1. the box is moving relative to yourself (clearly on a train in my advanced diagram..).

While in 2. it is just sitting there (the box that is).

Now the saw tooth thing is ment to be the path of the light when the box is moving. The line is just the one where it isn't.

Now cos the one which is moving has to move not only up and down but also along it has to go further. And yet it is light... which only goes one speed... which means time has to change to preseve it.

speed = distance / time

so

time = dist (diff) / speed (const) so time must be diff too (but instantatously in our way of looking at it it is the same, but it is actually different relative to each other.

quote:

Originally posted by NeoPhono Well, it wasn't two people, but they did have "twin" super-accurate clocks for an experiment such as that. They allowed one clock to orbit the Earth (for us Earthlings, that pretty much as fast as we get, unless you're traveling to another planet), while another "reference" clock stayed on the ground. After a fixed amount of time for the reference clock on Earth they compared the two and found there was a difference. Here's a pretty neat webpage that puts some of the more modern views of space time into at least potentially digestable form. http://casa.colorado.edu/~ajsh/home.html

TY, I knew they tried something about this theory

I love this stuff I would guess that reaching the speed of light would be a "supertask"

I thought as you approached the speed of light your mass increases such that when you reach the speed of light your mass would be infinite. Thats why its impossible to go the speed of light.

quote:

Originally posted by Jive_Turkey I thought as you approached the speed of light your mass increases such that when you reach the speed of light your mass would be infinite. Thats why its impossible to go the speed of light.

Basically, yeah.

And I'll be damned..my continuous trips to US and back caused my earthly lifespan to increase by a full 144 nanoseconds! And the trips I had with my car when I went on vacation and back added 3.6 nanoseconds more!

Powered by: vBulletin
Copyright © 2000-2021, Jelsoft Enterprises Ltd.