Travel Definition and 995 Threads

Travel is the movement of people between distant geographical locations. Travel can be done by foot, bicycle, automobile, train, boat, bus, airplane, ship or other means, with or without luggage, and can be one way or round trip. Travel can also include relatively short stays between successive movements, as in the case of tourism.

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  1. K

    Why FTL travel of light spot can't carry any information?

    http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html#3 But it didn't explain why. I just don't get it, let's say the spot travels from A to B, why can't I say some information travels from A to B, for example the shape of the spot?
  2. L

    Faster than light time travel through controlled, spatial distortion

    I have recently heard of a theory that states that faster than light time travel is possible by disrupting the fabric of space-time using tachyons, to create a makeshift wave behind a future spacecraft of some sort. It states that by doing this, one creates a bubble around the spacecraft ...
  3. G

    Exactly how is causality violated by superluminal travel?

    From my amateur readings in relativity, one of the arguments against tachyons is that causality would be violated locally. But how? Let's say we have observer A and B with synchronized clocks that are separated by a reasonable distance d known to them. A sends B a photon at A's clock t0...
  4. Q

    Determining distance of travel with friction acting on a car.

    1. A car is traveling at 51 mi/h on a horizontal highway. If the coefficient of static friction between the road and tires on a rainy day is .102 what is the minimum distance in which the car will stop. 2. f=un f=ma kinetics equations 3. No idea here. Teacher barely skimmed over...
  5. P

    How far will the GOLF BALL travel?

    How far will the GOLF BALL travel? I'm a business major, and was hoping that a few of the geniuses here could help me solve a problem! If a golf club was afixed to the front of a train (moving 100mph & assuming no loss of compression on the part of the train), and struck a stationary golf...
  6. S

    Is this idea of time travel consistent with relativity?

    This is the explanation I give people when they ask about time travel. I am only an undergrad so I just want to ask the more experienced people here if this is correct. Thanks... Time travel in the context of Einstein's relativity: So we all know that time travel into the future is easy...
  7. B

    The Van Allen Radiation Belt and Space Travel

    [Post edited by Ivan] I've heard that the intense radiation from the Van Allen belt would make it impossible to travel to the moon or send anything to Mars etc. It's obviously possible to have satellites or the ISS (which is only I think 330 miles above us). People say that the radiation from...
  8. Evo

    Ghost Adventures on Travel Channel

    First I don't understand why this show is on the Travel Channel. Some stupid guy that locks himself into supposedly haunted buildings overnight and films himself screaming and pretending to see stuff. For halloween they are doing a "live" broadcast where "viewers" can posts their comments and...
  9. T

    Exploring Einstein's Theory of Relativity: Can Time Travel Be Possible?

    Time time time Can the laws of gravity permit curving space and time in such a way as to make time travel possible. Einstein's theory of relatively states that the space/time continuum can be flat, but it can also be curved by gravitational fields. Perhaps time has three folds 1...
  10. S

    Debunking Time Travel Speculations: The Truth Behind Going Back in Time

    From what I've seen, most speculations of time travel seem to say that when you go back in time, everything else around you returns to an earlier state that it used to be. For example, if you stand outside your house and go back in time, the house will "un-build" itself and there will be nothing...
  11. M

    Electron travel in a wire; distance

    Homework Statement The starter motor of a car engine draws a current of 140 A from the battery. The copper wire to the motor is 5.0 mm in diameter and 1.2 m long. The starter motor runs for 0.95 s until the car engine starts. How far does an electron travel along the wire while the starter...
  12. M

    Electron travel in a wire; distance

    Homework Statement The starter motor of a car engine draws a current of 140 A from the battery. The copper wire to the motor is 5.0 mm in diameter and 1.2 m long. The starter motor runs for 0.95 s until the car engine starts. How far does an electron travel along the wire while the starter...
  13. R

    What is the effect of aging during space travel?

    Hello, I have been lately very interested in time dilation. I have found out many information about it and it's very interesting for me. But I have few problems I don't quite understand, so I will be glad for your help. Let's start: There's a man traveling in a spaceship from point A to...
  14. J

    Time Dilation and Future Interstellar Travel

    Hello all, I am new to the Forum and have no formal Physics training. I have an interest in the subject mainly due to other pursuits. I am reading Joe Haldeman's The Forever War. I would definitely recommend this book to anyone with an interest in Time Dilation or Humans vs Aliens at...
  15. E

    Is Travel to Parallel Universes Just a Myth or a Real Possibility?

    I was watching a show called "http://www.history.com/shows.do?action=detail&episodeId=373152" " on History Channel. It is claimed that someday it may be possible to travel to parallel universes. Does this not violate law of conservation of energy, mass and information? Would this action...
  16. F

    Mass to Momentum: Exploring the Physics of Space Travel

    A spaceship becomes lighter and easier to accelerate as it burns fuel. If it doesn't literally burn fuel, but it "magically" converts mass into to momentum with 100% efficiency, you will find that the limit of v as m approaches zero is c. You may ask, "At that limit (when v=c) where did all...
  17. D

    Do wormholes actually exist and can they be used for time travel?

    How is time travel possible? i understand that we can warp and modify time but i don't understand the concept... Is there any evidence to suggest that there are wormholes? if so how are they created?
  18. J

    Travel in space to Alpha Centuri

    I'm having a bit of a debate on traveling to AC. I was wondering if someone can post calculatons to show how long it would take traveling at 1g accelaration, and how much energy would be needed including any relativistic influences. Thanks
  19. vibhuav

    Is Time Travel Comparable to Space Travel in Physics?

    First of all, my background: I am an engineer interested in physics; so I am not very well versed with the nitty-gritty details and the math of physics. These are my thoughts and would like your comments: In some sense, time travel, being able to move back and forward in time is the...
  20. Pattonias

    A topic for amusement Debunking Time Travel

    I don't know if this has been discussed before, but I offer this paradox to debunk time travel. If time travel was possible, given an infinite amount of time from the point of its discovery and perfection; then someone eventually would have traveled back in time and made its existence known...
  21. M

    Does forces travel faster than speed of light?

    If speed of light is the upper limit of speed in the universe, how about force? (please refer to example for the paradox) For example if there is a block of wood 50 light seconds long floating in free space, say it weights only 1 kg and I apply 1 N causing it to accelerate 1m/s^2. So does the...
  22. O

    Is Mexico a Safe Destination for Young Adults and Kids?

    I had been reading about the troubles down there and was concerned about my young nephews and niece going there. Their father replied, "If you always listened to the State Department, you would never go anywhere." So then, what is a good way to determine if a destination is safe enough for young...
  23. A

    Travel Opportunities as a Physicist?

    As a Physicist (I was thinking mainly about those employed in academia which is why I posted this here and not in Careers Guidance) how much opportunity is there to travel? Many publications by the IoP to encourage students to study physics emphasize the international nature of a research...
  24. V

    Finding time of travel by falling object in drag coeeficient

    Homework Statement An object with mass 10kg is dropped from a height of 200m. Given that the constant k in the equation is 2.5Nsm^-1 mv'(t) = −mg − kv(t) approximately how many seconds does the object hit the ground? Homework Equations v' + (k/m)v = -g The Attempt at...
  25. R

    If she hits the brakes, how far will she travel before stopping?

    Homework Statement A person driving her car at 56 km/h approaches an intersection just as the traffic light turns yellow. She knows that the yellow light lasts only 2.0 s before turning to red, and she is 30 m away from the near side of the intersection (Fig. 2-29). Should she try to stop, or...
  26. H

    Is Time Travel Possible or Just Science Fiction?

    Is time travel is possible?
  27. P

    Speed of Light in Media: Why Does It Vary?

    Firstly, I must apologise if this thread is in the wrong place on the forums. I wasn't entirely sure where it might suit best. My question arises from something taken pretty much as read without much thought. That light travels through varying edia at varying speeds. I am curious as to why...
  28. S

    Time travel when velocity> light speed

    Not sure if this will have anything to do with quantum mechanics.. but... Ok so if you're traveling faster than light speed, then what do you see? I'm not talking about the whole doctor who scenario, its like traveling faster than sound, if the jet pilot is traveling faster than the sound it...
  29. S

    Is Time Travel Discussion Allowed in Physics Forums?

    i´m new in this fisics forum but, i would like tomake some questions about time travel...is there any specific place to put that kind of questions?
  30. D

    Is it realy true that nothing can travel faster than light? if so, why?

    How do the movement of a particle relate to the speed of light
  31. T

    Photons do not travel in straight lines

    I've been thinking about this for some time now and I wanted to get some feedback on it. If photons are supposed to travel along straight lines (for the sake of simplicity let's neglect the curvature of space-time), then how could one photon possibly be used in a double slit experiment? More...
  32. K

    Meat-eors: How fast does a steak need to travel to cook completely?

    Let's say you've got this steak and you've found a way to launch it in orbit and propel it back to Earth without any effect on the steak other than friction via air: http://a725.g.akamai.net/7/725/1095/000031/www.omahasteaks.com/gifs/big/ss031.jpg How fast does it need to go, for how long...
  33. A

    Light & Time Travel: Can the Light See Us Stopped?

    1.Light is moving so fast that is apparently stopped.But it ain't.Photons of light come and go. Now the question: Is light seeing us stopped?Like we arent moving? Thats a dumb question.Of course the light sees us stopped.If i ride a photon of light from Sun to Earth everything is stopped.8...
  34. T

    Paradox which questions time travel to the future

    You all have heard of the paradox whereas when you travel to the past and kill your grandfather you should not have existed in the presence whatsoever because you have killed your origins. So far so good...but I thought of another case, which I believe is more interesting since so far the...
  35. D

    Applications of realitivty once we can travel at near c

    One application I can think of is that if I had an incurable disease I could go on a one week ride in a spaceship, on return 50 years have passed on earth. Of course if there wasn't a cure I could just go on another trip.
  36. A

    Can We Travel Faster Than Light?

    I know that relativity doesn't permits a motion at speed of light or fast, as the Lorentz factor becomes infinite and we get absurd results, but what about wormholes or something, say wrap drive and what about http://en.wikipedia.org/wiki/Alcubierre_drive" and tachyons. Also I've heard that...
  37. P

    Exploring the Physics of Time Travel at Light Speed

    Why would time stop if you travel at the speed of light?
  38. T

    Minimum Travel Time: Is It Possible?

    I was considering this the other day, and I'm pretty sure I know the answer, but I want verification that I am not missing anything. Suppose you are in a rocket ship and you want to travel, say, to a star the nearest galaxy. Is there a minimum amount of time that would require? Since the...
  39. N

    What are the best places to travel in europe this summer 2009?

    Starting the trip off in geneva, and looking to go to germany possible austria and maybe parts of eastern europe.. 4 of us are students so budget is tight, but also looking to have fun i.e if they're any good festivals or cheap gigs going on. We're only traveling for 10 days so we're looking to...
  40. L

    The Truth About Time Travel: Separating Fact from Fiction

    So I was watching a video on youtube. http://www.youtube.com/watch?v=QM28eErikAo" It says that the faster you travel through space, the slower you travel through time, and that if you went faster than light, you could go back in time. Is this true? Forget about it being impossible to go...
  41. T

    Exploring Inertial Mass and Time Travel Possibilities

    No pitchforks please (and lay off the caps with the big 'D' on them too) Following staying up until 4am (all good stories start like this), and making small talk with a friend doing a degree in physics, we both decided to harp on about theoretical theories such as string etc, and as hours...
  42. T

    Name for a particular time travel paradox

    I have thought of an interesting property of time travel based on Novikov's self-consistency principle. I'm sure it's not wholly original, but if someone has heard of it before, I'd really like to know the name given to it so I can research it: If you find yourself next to a future version of...
  43. R

    Can We Build a Shaw-Fujikawa Translight Engine for Space Travel?

    I was watching the show Exodus Earth on the Science Channel, and they were talking about new methods of travel in space. Things like Ion Engines, Solar Sails, and Vasimir Plasma engines. I was reading a HALO book, is it mentioned how their Shaw-Fujikawa Translight Slipspace Engines worked. I was...
  44. E

    Special Relativity Time Travel to Future - Could You Watch the News on Earth?

    If you are traveling away from Earth on a spaceship near the speed of light, it is well known that the moving clocks on the ship run slower relative to stationary clocks on earth. I was wondering if while on the space ship, you could watch the news on TV and see events progress at a...
  45. T

    Compact Sapcetime and Time Travel

    Someone here once said to me, via post, that "any compact spacetime must have closed timelike curves". Are there any good references out there on why that is / how that is derived? As an after thought... Isn't it true that a particle traveling in one direction in time is equivalent to its...
  46. I

    Why does the sun travel faster about its equator?

    Would this be valid for all other planets as well?
  47. E

    Time Travel Theory: What Are Your Thoughts?

    What are your thoughts about this?
  48. M

    Calculating direction of travel on a clock face

    This is not a a school or college question, it is just for my interest. Homework Statement suppose I travel 605 meters North , then travel 673 meters West. I have calculated shortest distance of Sq Root(605^2 + 673^2) = 905 meters What I am now trying to calculate is direction to face...
  49. R

    Idea for light speed or possibly faster than light speed travel?

    So the other day while I was folding up some laundry I had this idea pop into my head. Now I'm not an expert or anything and I dropped out of physics in high school, but I do think quantum physics are interesting like most people. I figure this would probably be the best place to post this due...
  50. N

    Are proper travel distances contracted by SR?

    Imagine a hypothetical large region of empty, non-expanding space whose spacetime is flat. At the start of the scenario, a rocket sits stationary relative to our galaxy at a large proper distance "x", in the common inertial frame. Then at t=0 the rocket quickly accelerates to a constant .99c...
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