jesh Posted December 4, 2006 Share Posted December 4, 2006 [W]hy when you go on a plane doesn't your watch go wrong because you have traveled either forward or backward in time?It does go "wrong". The problem, however, is the difference is so tiny that it is unnoticeable. You'd have to have a much more elaborate and accurate time piece than a wrist watch to measure the effects of the time difference.EDIT: Here's a link: http://en.wikipedia.org/wiki/Hafele-Keating_experiment Link to comment Share on other sites More sharing options...
justsomeguy Posted December 4, 2006 Share Posted December 4, 2006 Wow, so you can actually travel forward or back in time, but why hwen you go on an aeroplane does your watch not be wrong appart from you being in a different time zone?It may be that the amount of the difference in time is so small that you cannot detect it easily. If a person was to do a considerable amount of air travel in one year, and never set their watch the entire year, you might be able to detect a change after the year. If the speed of light is 670,616,629 mph, and a plane travels at around 530 mph, then time will change at a very small rate.But, the distinction needs to be made, you're not travelling forward or backward in time. Time is simply moving at two different rates for the traveller and the observer. The traveller does not travel forward in time, time just passes more slowly for him then for the observer. I'm not sure of the amounts, I'm having a hard time finding references to the experiments that produced these results.* good call on the link. I started typing this an hour ago and just hit Reply Link to comment Share on other sites More sharing options...
jesh Posted December 4, 2006 Share Posted December 4, 2006 * good call on the link. I started typing this an hour ago and just hit ReplyThanks. Good job adding "you're not travelling forward or backward in time" because I seemed to have forgotten to mention that. Link to comment Share on other sites More sharing options...
Chocolate570 Posted December 5, 2006 Share Posted December 5, 2006 I know it was a sort of trick question in that I've always been confounded by the time difference theories with regards to light speed.What I'm getting at is that if our observance of someone travelling at the speed of light is hugely different to the actual person travelling at the speed of light, then surely that also applies to our observance of the time it takes light to travel from the sun to earth.If our observation of the time it takes for light to get here is 8 minutes, then this is surely a distortion of the time it actually takes for the light particle to get here.Actually, I believe that if you're traveling at the speed of light for 8 minutes, you've reached an infinite distance in relative terms to the person next to you, as all time stops around you. Link to comment Share on other sites More sharing options...
justsomeguy Posted December 5, 2006 Share Posted December 5, 2006 One thing I saw that was interesting is that the speed of light is always relative. Someone can never catch up to light. If a beam of light takes off, and someone starts chasing it at a speed approaching the speed of light (or at the speed of light), they will still see the light moving away from them at the speed of light. Even though an observer would see the beam of light and the traveller both moving at the same speed of light, the traveller would still see the beam of light moving away from them at the speed of light. So the speed of light is relative to whoever is observing it, it is not a speed limit. Link to comment Share on other sites More sharing options...
jesh Posted December 5, 2006 Share Posted December 5, 2006 One thing I saw that was interesting is that the speed of light is always relative. Someone can never catch up to light. If a beam of light takes off, and someone starts chasing it at a speed approaching the speed of light (or at the speed of light), they will still see the light moving away from them at the speed of light. Even though an observer would see the beam of light and the traveller both moving at the same speed of light, the traveller would still see the beam of light moving away from them at the speed of light. So the speed of light is relative to whoever is observing it, it is not a speed limit.Yeah, it's hard to grasp. If a spaceship is crusing along at 99% of the speed of light and the captain turns on some headlights (or fires a laser), the light being emitted from those headlights (or the giant laser) would move away from the spaceship at the spead of light. Meanwhile, an observer watching this whole thing take place on a moon below would see the beam of light from the headlights traveling away from the spaceship also at the speed of light (rather than 1.99 times the speed of light).The difference in the two situations is how distance and time are measured. The observer on the planet would record much more time having elapsed than the captain in the spaceship. Link to comment Share on other sites More sharing options...
Agustine Posted December 5, 2006 Share Posted December 5, 2006 I don't believe any object would be able to sustain traveling at the speed of light. See when two cars traveling at say, 50km per hour crash into one and another the force of the impact is 100km per hour on both cars. Or if just one car at a 100km per hour crashes into say a tree, the force of impact on the tree and the car is 100km per hour. So, if you apply this to traveling at the speed of light, any object that the object traveling at the speed of light came into contact with – even a very small object such as pebble – would have very damaging effects. A Kleenex box traveling at 40km per hour can give a person a serious concussion. Link to comment Share on other sites More sharing options...
justsomeguy Posted December 5, 2006 Share Posted December 5, 2006 That's one of the strange things about light - those cumulative effects do not apply to light. This is from the "Physics" section of the wikipedia page, where it gives the formula as well: Most individuals are accustomed to the addition rule of velocities: if two cars approach each other from opposite directions, each travelling at a speed of 50 km/h, one expects that each car will perceive the other as approaching at a combined speed of 50 + 50 = 100 km/h to a very high degree of accuracy.At velocities at or approaching the speed of light, however, it becomes clear from experimental results that this rule does not apply. Two spaceships approaching each other, each travelling at 90% the speed of light relative to some third observer between them, do not perceive each other as approaching at 90% + 90% = 180% the speed of light; instead they each perceive the other as approaching at slightly less than 99.5% the speed of light. http://en.wikipedia.org/wiki/Speed_of_lightA Kleenex box traveling at 40km per hour can give a person a serious concussion.Given enough velocity, Kleenex boxes sitting in the back of people's cars have scalped the driver in a collision. Link to comment Share on other sites More sharing options...
reportingsjr Posted December 6, 2006 Author Share Posted December 6, 2006 A Kleenex box traveling at 40km per hour can give a person a serious concussion.Actually, just to say it, that was disproved. Myth busters , gotta love that show! But they did that one and all it did was hit the dummy, no damage at all. So I have to disagree with you! Light is fast! Link to comment Share on other sites More sharing options...
holmedwa04 Posted December 6, 2006 Share Posted December 6, 2006 I know that this isn't really a question about this topic, but it is similar, so anyway, why can anything only travel up to a certain speed, I think it is called the universal speed limit, what is stopping it? I think the number is something times ten to the power of something. Or something very similar. Link to comment Share on other sites More sharing options...
justsomeguy Posted December 6, 2006 Share Posted December 6, 2006 The speed of light was thought to be the upper limit that things can move at, but some experiments show that not to be the case. Gravity and electrodynamic forces both move at speeds far greater then the speed of light. I believe the speed of light is thought to be the upper-limit for matter that is moving, because experiments have shown that as matter approaches the speed of light, it increases in mass. So, the energy required to have the object increase in mass gets so large that the object can't go any faster because it can't increase in mass. There's a brief discussion about that here:http://www.physlink.com/Education/AskExperts/ae91.cfm Link to comment Share on other sites More sharing options...
jesh Posted December 6, 2006 Share Posted December 6, 2006 The speed of light was thought to be the upper limit that things can move at, but some experiments show that not to be the case. Gravity and electrodynamic forces both move at speeds far greater then the speed of light.Do you have a link that supports that? I'd be interested in reading it. I was under the impression that electromagnetism (i.e. light) travels at 3 x 10^8 m/s and nothing can travel faster than that. That is, unless you are entering the realm of quantum physics where things travel around all willy-nilly. Link to comment Share on other sites More sharing options...
justsomeguy Posted December 6, 2006 Share Posted December 6, 2006 Sure, but make sure your nerd hat is strapped on tightly:http://metaresearch.org/cosmology/gravity/speed_limit.aspHere is the short abstract: General relativity has a geometric and a field interpretation. If angular momentum conservation is invoked in the geometric interpretation to explain experiments, the causality principle is violated. Meanwhile, the field interpretation avoids this problem by allowing faster-than-light propagation in forward time. Lightspeed is not a universal speed limit.And the general abstract (note the last sentence):The mathematical equations of general relativity are unique, but their physical interpretation is not. Confusion reigns over the difference between the field and geometric interpretations of GR, the meaning of gravitational force in a GR context, the distinction between gravitational waves and force variations, and the applicability of aberration to gravity. The geometric interpretation of GR, argued by Carlip, blurs these concepts. We show that aberration has been suppressed in the GR equations of motion through setting gravity’s propagation speed to infinity; and that the absence of aberration cannot be explained through some mathematical “cancellation” because that would cancel tidal forces too. The mere existence of Lorentzian relativity as an experimentally viable model for the relativity of motion nullifies the “proof” that nothing can propagate faster than light in forward time. Experiments indicate that gravity and electrodynamic forces both propagate far in excess of lightspeed. Link to comment Share on other sites More sharing options...
reportingsjr Posted December 6, 2006 Author Share Posted December 6, 2006 But gravity and electrodynamic forces have no true speed, because the speed is unattainable. You try and figure out the speed you want. Also how do you figure out the speed of light? Its not matter or anything, did they have someone out in space look for a big light on earth and check what time they saw it, and check what time the people turned it on at? (or blew up or what have ya!) Link to comment Share on other sites More sharing options...
justsomeguy Posted December 6, 2006 Share Posted December 6, 2006 They don't need distances that large. They can shoot a laser several miles and, using computers, determine the fraction of time between the time the beam was emitted and the time when it struck the other end. Also, there are in fact particles of light (photons), but light is unique in that it exhibits the behaviors of both particles and waves.The force of gravity does have a speed, if a gigantic object instantly materialized at a point in space, gravity from that object would not instantly effect everything in the universe. It would take some time for the effects of the gravity to be felt, depending on the distance between the objects. And, speed is a measurement of distance vs. time. Link to comment Share on other sites More sharing options...
jesh Posted December 7, 2006 Share Posted December 7, 2006 Sure, but make sure your nerd hat is strapped on tightly:http://metaresearch.org/cosmology/gravity/speed_limit.asp HA! I seemed to have left it at home this morning. Maybe I'll get it at lunch. Thanks for the link! Link to comment Share on other sites More sharing options...
reportingsjr Posted December 8, 2006 Author Share Posted December 8, 2006 Hmm, I dont know about the gravity one! Where do you find this at again? Wikipedia and google you say? Link to comment Share on other sites More sharing options...
Chocolate570 Posted December 8, 2006 Share Posted December 8, 2006 I know that this isn't really a question about this topic, but it is similar, so anyway, why can anything only travel up to a certain speed, I think it is called the universal speed limit, what is stopping it? I think the number is something times ten to the power of something. Or something very similar.Just to tell you, "something times ten to the power of something" is called scientific form. It is used for astronomical calculations and just basically big numbers. For example, if you have the number:500,240,524,525,852,085In scientific form, it would be:.500240524525852085 x 10^18:)Well, at the speed of light, mass doesn't exist, so that's basically the universal speed limit. Link to comment Share on other sites More sharing options...
reportingsjr Posted December 8, 2006 Author Share Posted December 8, 2006 Scientific Notation . BTW chocolate. I know your name *gasp*. , its your secret weakness, like superman to kryptonite. :)You still never know! Link to comment Share on other sites More sharing options...
holmedwa04 Posted December 8, 2006 Share Posted December 8, 2006 Scientific Notation . BTW chocolate. I know your name *gasp*. , its your secret weakness, like superman to kryptonite. :)You still never know!Now that is what I call random and oh yes, I knew it was called scientific form, I was just having a senior momnet and so I had to write it like that! Link to comment Share on other sites More sharing options...
reportingsjr Posted December 10, 2006 Author Share Posted December 10, 2006 Today or yesterday night NASA had a successful launch . They launched the Discovery, I think. It's going to dock with the space station and they are going to install permanent wiring instead of the temporary wiring they have right now. Man! The Space Station just keeps progressing, soon people can live a board it forever . Link to comment Share on other sites More sharing options...
holmedwa04 Posted December 10, 2006 Share Posted December 10, 2006 How could they do that, they wouldn't have enough food? Link to comment Share on other sites More sharing options...
reportingsjr Posted December 11, 2006 Author Share Posted December 11, 2006 Make an ecosystem on board.. Thats what I was implying. Link to comment Share on other sites More sharing options...
MrAdam Posted December 12, 2006 Share Posted December 12, 2006 after reading all that in one go i have a bit of a headache... Link to comment Share on other sites More sharing options...
aspnetguy Posted December 12, 2006 Share Posted December 12, 2006 Today or yesterday night NASA had a successful launch . They launched the Discovery, I think. It's going to dock with the space station and they are going to install permanent wiring instead of the temporary wiring they have right now. Man! The Space Station just keeps progressing, soon people can live a board it forever .Except for the fact that their muscles would turn to jello Link to comment Share on other sites More sharing options...
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