Travel Definition and 994 Threads

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...

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?

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...

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...

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...

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...

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...

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...

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

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...

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...

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.

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...

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...

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...

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?

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...

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!

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...

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?

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...

[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...

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...

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...

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...

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...

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?

-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...

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...

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...

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...

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

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...

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...

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

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...

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...

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...

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...

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...

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...

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:

i have a question for your minds to wonder about. i don't know the answer but i would love to hear your opinions or facts if you have any. now i am probably the hugest trekkie a person can be. i love star trek, it is one of the things that got me into science. anyways, what makes Star Trek...

this came to me in a dream state meditaion a few days ago everything from light to sound to time all travel along some line and travel all at different speeds. but if you are able to cause mulitple fission explosion for a brief moment everything around that implossion will be sucked inward...

towing a travel trailer... hello everyone, i belong to several classic trailer sites and there is an issue concerning towing a trailer without brakes. can someone tell me how to determine the force generated, say in pounds per square inch, of a trailer weighing 1400lbs, moving at 65 miles...

Need some help. How fast are the human feet traveling as they pass each other while walking and running? Thanks.

does anyone thinks time travel is possible?

Hello, This is my first ever post in an entirely science-dedicated forum. On another forum, another user and I theorized that the energy transfer in hydraulics from one point to another is instant. He initially posted about electricity being instant because electrons move at the same speed...

as the waves travel through a medium, they lose velocity, however the frequency is constant right? thanks

For me its all about nature. Before I go to any city, I would like to see the arctic tundra (above the tree-line), the savana, the Sahara, the Australian Outback, Antarctica, the rainforests. Human formations can wait! I honestly think that other than my career, seeing the different...