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. L

    FTL travel: Do you think we can do it?

    I think YES! I'm a fan of quantum tunneling, or put simply, raising the speed of light. There have been a few successful experiments proving this, like the one performed by Günter Nimtz in 1994, who sent a FM broadcast of Mozart's 40th at 4.7 times the speed of light.
  2. B

    Traveling into the future in order to travel back into the past

    Have physicists ever consider traveling into the future in order to travel back to the past? I know it sounds crazy, but one of the paradigms for time travel is Godel's closed time loop curve, where time I think is circular rather than linear. Special relativity permits travelers , if they...
  3. J

    Noob with a question about lightspeed travel.

    I would like to preface this idea by stating that I am a total noob and in no way have any right to be here haha. I was just watching a show on the science channel "Carl Sagan's Cosmos". I am an avid viewer of basically anything on TV about the universe or physics in general. I find...
  4. A

    Can information travel faster than light?

    Theory of Relativity says nothing can exceed the speed of light. My question is: Can any information be made to travel faster than 'c'? suppose, i have a light torch of very high intensity which can be rotated on an axis(its stand). the light is made to fall on a wall(extending for millions...
  5. H

    What is the distance travel by the ball when the time is 1 sec?

    i throw a ball upwards reach highest point at 3secs later what is the distance travel by the ball when the time is 1 sec? take g = 10m/s^2 another is a car deccelerates from 20m/s at a rate of 2ms^2... how long does it take to reach 100m im trying to explain it to my younger...
  6. G

    Where Can I Find Projectile Travel Graphs?

    I am looking for a link to some graphs that illustrate horizontal and vertical flight of a projectile. Anyone have a suggestion? Thanks.
  7. J

    How long does it take this transverse wave to travel along a string

    Homework Statement If the combined string is under tension F, how much time does it take a transverse wave to travel the entire length 3L? Give your answer in terms of L, F, and mu_1. Three pieces of string, each of length L, are joined together end-to-end, to make a combined string of...
  8. S

    Plasma Drag Reduction & Hypersonic Travel

    I'd heard this was a relatively newer discovery -- that a blunt-body object traveling through a gas experiences a reduction in drag if that same gas is turned into plasma. I'm haven't read exactly why this occurs, but I'd presume that a gaseous fluid medium becomes easier to pass through if...
  9. CJames

    Tachyons travel backward in time?

    The time dilation equation: \Delta t' = \Delta t/\sqrt{1 - v^2/c^2} Now let's consider a tachyon with v = 2c \Delta t' = \Delta t/\sqrt{1 - (2c)^2/c^2} \Delta t' = \Delta t/\sqrt{1 - 4c^2/c^2} \Delta t' = \Delta t/\sqrt{1 - 4} \Delta t' = \Delta t/\sqrt{-3} \Delta t' = \Delta...
  10. P

    Is Part of the Observable Universe Moving Faster Than Light?

    Is there a part of today's observable universe that is traveling away from us at faster than light speed? (relatively speaking, of course) Is the known universe large enough for a cumulative expansion rate to exceed light speed?
  11. S

    Is it not possible to travel in light speed?

    Hi I am just wondering if E = mc^2 then wouldn't it also be correct to say 1/2mv^2=mc^2 since E is kinetic energy. So in order for an object to travel near light speed, it has travel twice (1/2v^2=c^2) the speed of light according to the above formulae. But according E=mc^2 light speed is the...
  12. M

    Can Anything Travel Faster Than Light - Explained Simply

    Well, it's an interesting thought, but one that I can't quite believe, or maybe more I can't understand how, something can travel faster than light? I've read this wikipedia, and although a few people don't trust what is written on wikipedia, I have heard of it before. Could anyone explain...
  13. M

    Space travel, mass increase, and length shorteneing

    Alright, i have a final and i have to explain just three parts to einstein's theory of relativity... they are space travel (time slowing nearing the speed of light), increase of mass with speed, and length contraction... the space travel makes no sense, and the mass one, i have mixed feelings...
  14. S

    Calculating Sound Travel Time at 20°C

    Homework Statement The distance between a loudspeaker and the left ear of a listener is 1.90 m. (a) Calculate the time required for sound to travel this distance if the air temperature is 20°C. Homework Equations I am not sure, I tried looking in my text...but the only equation I...
  15. D

    Where does time travel fastest? And a moving galaxy/light speed question.

    Hello, I’ve been browsing these forums for a while now; I like physics and I get really interested in all sorts of physics stuff. My main interest is space because I find it really fascinating. I have two questions that I’ve been curious about for a while now; The first question is about...
  16. C

    Why does sound travel faster in warm air?

    I thought sound always travels faster in a denser medium - For eg, it travels faster in water than in air. And I believe that's because the molecules are packed closer together, so the vibrations are transferred faster between them, hence more speed. But then why does sound travel in less...
  17. I

    Can light travel faster than itself?

    I am hoping someone could let me know how far light can travel?
  18. R

    Calculating Light Travel Time in Glycerine: A Homework Guide

    Determine the time it takes for light to travel 54 cm through glycerine in an aquarium. does anybody know how make an equation for this??... because I just have no clue with this one...
  19. W

    Why massless particles must travel at c

    Homework Statement give a logical argument for why a particle with m0 = 0 with nonzero energy has to move with a speed equal to c. Homework Equations The Attempt at a Solution I attempted using the momentum equation but I always get a multiplication by 0 which doesn't make sense...
  20. B

    Is High Speed Space Travel Feasible with the Risk of Space Debris?

    Wouldn't high speed travel in space be near impossible even if we could get to around the speed of light. Specs of space dust would most likely obliterate the spacecraft . A fleck of paint almost ruined one satalite and it was going about 22,000mph.
  21. K

    How do two waves travel through eachother, coming out unchanged?

    Hi all, My question initially came to me as I was thinking about standing waves, in that how do waves interfere, and then come out unchanged after this interference? For simplicities sake, imagine we have two wave pulses coming toward each other on a string. Now let's say they are out of...
  22. M

    Exploring the Possibilities of Time Travel

    Hello everyone, I am new to this forum and would greatly appreciate your expertise in answering (or attempting to) a few questions for me. I don't care if you focus on one or all of them, but any answers are appreciated! These are about time travel, with a focus on traveling BACK in time...
  23. M

    Time Travel: Will it ever be possible, how soon, how far, etc.

    Hello everyone, I am new to this forum and would greatly appreciate your expertise in answering (or attempting to) a few questions for me. I don't care if you focus on one or all of them, but any answers are appreciated! These are about time travel, with a focus on traveling BACK in time...
  24. A

    Does moving at high speeds actually slow down time?

    the basic theory is that if you travel fast enough then time will go slower for you then the rest of the universe. doese anybody know if this is true or not?
  25. W

    Brightness detected based on direction of travel relative to source

    I don’t see that this question has been asked before and I am hoping the generous moderators of this forum will be able to answer it. Suppose you have the “standard” situation with the man M on the embankment and the woman W in the center of the moving train car. (The train has lots of...
  26. Z

    Find initial speed, travel time and max height above the ground

    A projectile is fired from 35ft above the ground level at an angle 35 deg. It hits the ground 100 ft away (horizontal distance). Find initial speed, travel time and max hight above the ground. can somebody solve this or point me in the right direction, thank you!
  27. G

    Apparent position and light travel time

    This is a thought of mine... or popping my 2 cents into the pot. I think it is fine to have the speed of light as constant. It does seem to me that we are missing one important facet when I consider it. It has to do with position. Where things are... ... relative to us. I...
  28. L

    A rocket can't travel faster than the speed of light

    A rocket can't travel faster than the speed of light. What would happen if you sent off a rocket going at 0.5c in one direction, and then sent off another rocket going at 0.5c in the opposite direction? Wouldn't one be traveling at the speed of light, relative to the other?
  29. B

    Finding the distance an object will travel

    Hi. I have a question about finding the distance an object will travel along a horizontal surface. If I have a force striking an object directly in the horizontal direction, how would I go about finding how far it will travel? I already have found the frictional force acting on the object...
  30. C

    Unlock M1 Level Question: Total Time to Travel 4 km

    [SOLVED] M1 level help Hi. Could someone please help me with the following M1 level question? I would really appreciate any help as I am really stuck at the moment. A car starts from rest at a point S on a straight racetrack. The car moves with constant acceleration for 20 s, reaching a...
  31. M

    A question with masses and distance to travel, find the time to travel so far

    Homework Statement Jane wishes to quickly scale a slender vine to visit Tarzan in his treetop hut. The vine is known to safely support the combined weight of Tarzan, Jane, and Cheeta. Tarzan has twice the mass of Jane, who has twice the mass of Cheeta. If the vine is 60m long, what minimum...
  32. M

    Can a Gravity Shield Allow for Superfast Travel?

    Hi, is it possible in (theory) to somehow combine lots of atoms, protons ect and make a shield that pushes gravity outwards in every direction so the aircraft or whatever was the weightless? if that were possible, would we be able to travel near the speed of light or even 1/4 the speed of light...
  33. S

    How is electron formed? Why does it travel?

    I understand that electron is made up of leptons which are made up of energy. But what I don't understand is that how can leptons be just made up of energy, I mean its not like a balloon. Another thing is that Wikipedia claims that Leptons and Quarks are the only 2 fundamental particles...but...
  34. A

    Time for pulse to travel a length

    Train problem Homework Statement 005 (part 1 of 1) 10 points A 23-car train standing on the siding is started in motion by the train's engine. There are 4 cm of slack between cars. The cars are 9 m long. The engine is tightly connected to the first car and moves at a constant speed of...
  35. wolram

    Gravitational Lensing and Frequency-Dependent Light Travel Time

    Light that has traveled millions of years is gravitationaly (lensed) around a body, if there is any frequency dependant light travel time ,would it not show up as if it had been split by a prism when it was lensed around said body, or would the various frequencies recombine?
  36. G

    Symmetry in Travel and Time Dilation

    -Is it possible for two objects to have symmetrical geodesics in which each accelerate with equal magnitude but in opposite directions? If not why not? -If so, how can both see each others clocks run slow? Would one have aged less than the other when then they reunite? Which? If not what...
  37. E

    Exploring the Paradox of Faster-Than-C Travel

    Even if someone could travel faster than c, could he return before somewhere before he set out? Could she arrive at some intermediate destination before she set out? Draw a spacetime diagram representing this trip? OK. Obviously the first question is no because in a spacetime diagram your...
  38. Q

    Can Future Generations Really Travel Back in Time?

    Note: For copyright reasons, I'm trimming the original post, which appears to be a direct quote from http://news.yahoo.com/s/livescience/20070820/sc_livescience/timetravelmachineoutlined Also, the peer-reviwed article is at...
  39. J

    Understanding the Mechanics of Sound Travel: A Physics Perspective

    How does sound travel? Does sound travel merely by vibration of particles in the media? To my imagination, the sound propagates as follows: The atom/molecule close to the sound source moves towards the neighbouring sides. The repulsion from one electron in the atom moves the electron in the...
  40. Ivan Seeking

    Time travel discussion with Ron Mallet tonight

    Dr. Ron Mallett shares his research into time travel. http://www.coasttocoastam.com/ This is highly controverial, and my understanding is that it has been shown that his solutions are not valid. A PF discussion about this: https://www.physicsforums.com/showthread.php?t=147946
  41. I

    Exploring Spacelike Travel: Understanding its Limitations and Significance

    so all movements in spacetime are timelike except light which is lightlike. are any spacelike? i understand this essentially means going backward in "time" but if it's impossible, which it is generally is believed to be, it seems to me like there is no physical significance to being outside the...
  42. D

    How fast does light travel in 1 ft?

    Hello everyone, I was wondering if anyone could help solve my problem... ...How much time in seconds (or milleseconds) would light travel in 1ft? (assuming that it was traveling in a vacuum.) I spent 2 and a half hours yesterday trying to solve this problem, but without much luck. I...
  43. R

    Calculating Torpedo Angle & Travel Time to Hit Carrier 5 Miles N

    need help.. carrier 5 miles N of sub traveling E @ 3mins/hr. sub has torpedoe travel @ 40 knots. what is the angle and distance travel of torpedoe to hit carrier, what is travel time . with respect to original sighting
  44. U

    What are the factors which affect the travel of sound through

    What are the factors which affect the travel of sound through different mediums? You does sound travel faster through a solid than a gas, is it because of the greater density of the solid, or because of the stiffness of the solid? Does sound travel faster in humid air, or dry air? many thanks...
  45. B

    Time dilation spacecraft travel problem

    Problem: How fast must a spacecraft travel relative to the Earth for each day on the Earth to correspond to 2 days on the earth? My solution: proper time = 1 day = 86400 seconds time on space craft= 2 days= 172800 seconds relavant equation: t=t(0)/(sqrt(1-v^2/c^2) I would plug in...
  46. V

    Why doesn't QM make particles zig-zag as they travel?

    Pardon my ignorance, I'm pretty sure this has an obvious answer, but it's something I've been wondering about. In QM it's said that particles don't exist in a definite state between measurements, but rather exist as a wave function, with a probability of being found in a certain place when...
  47. L

    Can we travel faster than the speed of light?

    Im only 14 and I am having a argument with a friend and teacher, and I need to know is is possible in theory to go faster than the speed of light and what is it? Time travel whatever, they don't believe me that you can and I remember reading it somewhere but the fact is no one knows how to do it...
  48. S

    Does black hole's gravity really travel out of it's own Event Horizon?

    To Physicists/Administrators/Moderators: The following two facts raises a doubt 1) "No influence can travel from inside the Event horizon of a black hole to the outside of it AT or below the speed of LIGHT (V<=C)." 2) "Gravitational influence travels AT (or below?) the speed of light...
  49. D

    Nothing can travel faster than light

    A question has been in my head for some time and I have yet to find an answer when I researched it. I know that nothing can travel faster than light, but WHY? All observers, no matter what speed they are traveling to or from the source of light, see the light as coming at them at 670...
  50. R

    The Mystery of Cold Air Travel: Light vs. Heat

    How does cold air travel? Isn't it like me flashing darkness at your face? Because cold is the absence of heat as darkness is absence of light. It's like nothing traveling. I know it's confusing.:confused:
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