Travel Definition and 994 Threads

Homework Statement How do you find the time it takes for light to travel 54 cm through glycerin (index of refraction = 1.470 at 20˚C) in an aquarium? Homework Equations These equations might be useful: v= 331 m/s + (0.59 m/s/c˚)(T) niSinθi=nRSinθR The Attempt at a Solution v=...

I'm still having trouble with this: Generically, work = m * d^2 / t ^2 (mass, displacement, time) If to a 1kg mass at rest in space I attach a small rocket that fires with a force of one Newton for one second, at the end of that period the mass will have traveled 0.5 meters, and the rocket...

The argument I've heard following from Special Relativity is as follows: Assume a causal influence can travel faster than c in a given reference frame, and assume it starts at Event A and is the cause of Event B a short time later (Events A and B are also at different points in space). This...

Question: Suppose that the travel time from your home to your office is normally distributed with mean 40 minutes and standard deviation 7 minutes. If you want to be 95% certain that you will not be late for an office appointment at 1p.m. what is the latest time that you should leave home...

Hi! I always wonder, why "Time Travel" equation make use of velocity of an object ( speed of light etc.) Why not it is related to the state of objects constituting the universe. Say, in my tiny imaginary universe, that just consists of me and a road from point A to B. A...

So...long story short: Would you pay online a travel in outer space - scheduled 5 years from now for a realistic price of below $10,000? Or...you would rather think that this is some sort of a total scam and a ponzi scheme? I am asking because a close friend of mine who is a lead engineer at the...

i am amazed by the possibility that if the light reflected from Earth comes back to us after traveling in space for thousands of years we will be able to see our past. And this could happen around black holes. Has anyone found an image resembling earth?

Why does light travel so... It finally happened!

although compared to us light travel super fast if you take a step back one will see that copared to the gigantic universe light travels very slow. can there be any thing that travels faster than light?

I was looking at the sky and I began to think about the stars. Obviously they emitted their light years ago because as we know, light is fast but not instantaneous. That the sky and stars as we see them, are not anymore because its only a view of their light omitted years ago. My point is that...

"Once confined to fantasy and science fiction, time travel is now simply an engineering problem." Michio Kaku If time travel were to be operational right now and I want to go 5 days towards the future and record all the events that have transpired, and go back again to the present time, am I...

why does light travel so fast?

Hello All, I'm trying to wrap my head around SR and I have a couple questions: If two space travelers (A) and (C) take off from a Planet (B) in opposite directions and each travels just over 1/2c, do they vanish from each others' view? I don't see why they wouldn't but If yes, doesn't...

Hi, I have a simple question in my mind, I could not find the answer anywhere so I came here. Here is my question, Assume a source of light and observer are five light seconds apart, and are travling parllel to each other at a constant speed of say 200 meters per second. Now if the source of...

They say that faster than light travel is impossible. However, if you made a rod 1 light year long and someone was standing at the other end when you bumped it. They would feel it immediately. The kinetic energy generated by the poke reaches the person before the light. Kinetic energy is an...

So I'm kind of new to the whole physics thing so be nice please :P If i guess "nature" keeps objects from being able to go the speed of light then does "nature" keep light from going slower/faster than that speed? I first thought of this when i read a thread asking if gravity actually...

Homework Statement hiya, I have a question here ; A truck driver traveling at 100km/h puts his truck into neutral just as the trurck starts up an incline of 15° above horizontal. a) calculate how far the truck will travel before it comes to a stop? Homework Equations We haven't...

I recently came across an article relating to Gliese 581 g and some theoretical information about getting there. It said something along the lines of "while it is 20.3 light years from Earth, passengers aboard a vessel traveling at nearly the speed of light would perceive the journey as nearly...

Sorry, but I only have very limited knowledge in physics. I came to ponder the concept of time travel. Backwards time travel has been a topic of discussion for as long as man has pondered his own existence. However, what this simplistic discussion attempts to do is to explain how backwards...

Simply because there is no past or future to go to. Only the present exists. Or at least that is what I think. If time travel is possible, why do we have no visitors from other times?

Homework Statement Two recording devices are set 2400 feet apart, with the device at Point A to the west of the device at point B. At a point on a line between the devices, 400 feet from point B, a small amount of explosive is detonated. The recording devices record the time the sound...

Black holes-- time travel? Is it plausible for something to time travel by means of a black hole, or is that entirely science fiction?

Homework Statement Estimate whether dead cattle (used for pork) will come out well done, medium or rare when put through a tunnel that goes through the centre of the earth?Homework Equations Because it says estimate, I’m not entirely sure if detailed calculations are needed. The Attempt at a...

I don't have an extensive physics background, so I apologize if there's a well known or obvious answer to this question. I'm familiar with the Newtonian version of time in which it's treated as a kind of fourth dimension. So there's x,y,z and t. Sitting here typing this, time is passing for...

Hello, so last night something occurred to me that I thought perhaps some of you might find interesting and enlighten me with validation. As I understand light travels at c in a vaccum. When light propogates through our atmosphere and through other particles it travels slower than c. Does...

I apologize if this topic has been discussed before. Although it seems basic enough, I failed to find any discussion on it. I just can't seem to make sense of this simple thought experiment - traveling toward a light source. Lets say there was a star 1 light year away from Earth and I traveled...

could this be proof of time travel? and would it be physically possible to one day time travel if this is not real? http://www.youtube.com/watch?v=TiIrpEMbQ2M&feature=player_embedded

Okay, I'm trying to get a grasp of how exactly wormholes function, how they form, etc. Please correct any and all flaws/mistakes in my understanding and further educate me, if you please. :) A wormhole could, theoretically, span any distance. Though the greater the distance (relative to our...

I am in grade 8 so please no gradute equations I would like to know if going through a wormhole (and survied) would you have travel faster then the speed of light creating possible time travel

1. Apartment dwellers will testify that bass notes are more distinctly heard from music played in nearby apartments. Why do you suppose lower-frequency sounds travel through walls, floors, and ceilings more easily? 2. n/a 3. Lower frequency sounds travel through walls, floors, and...

Electromagnetic wave peaks don't "travel" through space? I'm just checking my understanding. When a wave travels through water, you can see the peak of the wave move gradually through space. But, it seems that an electromagnetic wave is different in that the peaks of the waves do NOT...

Homework Statement the following is a equation to find the displacement of a particle. I've found it is instantaneous at rest at t=5. now need to find the distance traveled between 0 to 10s. i found distance traveling between 0 to 5 s is 7.5 but no idea how to find distance traveled between 5...

I'm not sure if this is the right forum for this, sorry if it isn't. I was presented with the idea that to travel in time, we could make a train track around Earth. On the track, there would be a train that traveled at 99.999% of the speed of light and would travel in time. A girl gets up...

I've read about 'ergosphere' in wiki and surprised at the information presented that ergospheres around very fast spinning black holes can drag space time many times faster than light! Such that any object that falls into this spinning ergosphere, will also begin to 'accelerate' to match the...

QUESTION: How far will a car travel in 15 min at 20 m/s?The answer was 18 km. but i don't know from where did they get this answer...can you explain it please step by step?? Thank you =)

For simplicity consider an unmanned probe to a star in our neighbourhood say 10 to 20 LY. Most discussions of this concentrate on speed and power. But what is the fastest realistic velocity? 40,000 MPH (~ 1/10 of 1% of light speed)? Even at this speed interstellar dust banging away at the...

There is a very very big space-ship in which light takes 1 second to reach from one corner to other corner. if two signals are sent one after other,what will be the amount of time for second signal to reach other corner? If spaceship is traveling with uniform acceleration(very high for our...

This is not an attempt at humor or controversy. I spend my spare time trying to find truth. I have been trying to understand some of Physic's theoretical ideas, and to my chagrin, many of them seem preposterous. I hope there are people out there that have the time and patience to help me...

There are a lot of "IF's" in the following, so this may be more a question of logic than of physics. Also, I have two questions revolving around the same themes; they are independent from one another so a response can be to one or both of them. (1) In...

Homework Statement a mountain climber plans to jump from A to B over a crevasse. Determine the smallest value of the climbers initial velocity Vo and the corresponding value of the angle alpha so he lands at B Homework Equations A to B is 1.8m horizontal distance and B is lower than A...

So, as something with rest mass gets closer to the speed of light, it gains more mass, making it require greater force to accelerate it making it gain even more mass and so on. So the reason we use to say nothing can travel at or faster than light is because it gains more mass, and requires more...

Source http://en.wikipedia.org/wiki/Cruise_(flight ) then totally opposite statement What essentially is cruise speed

I understand that modern day Physics allows for travel into the future, but not the past. I understand that time slows down the closer and closer you get to the speed of light, so that you never exceed that limit. But what if you meet it? I know because of the laws of Physics, you couldn't meet...

Homework Statement t seconds after the brakes of a car are put on, the acceleration of the car is a(t) = -6t - 4 ft/sec^2. If the automobile was moving at the speed of 32 ft/sec when the brakes were put on, how far does it go before stopping? Homework Equations a(t) = -6t - 4 ft/sec^2...

Hey everybody, I need help on a few word problems. The major problem I'm having is finding a formula to use. A bus is going to a football game and leaves at 4:00pm. It travels 20.91 miles to the game in 33 minutes. What is the bus' average speed in miles per hour? I'm completely clueless...

Homework Statement An explorer is caught in a whiteout (in which the snowfall is so thick that the ground cannot be distinguished from the sky) while returning to base camp. He was supposed to travel due north for 4.4 km, but when the snow clears, he discovers that he actually traveled 7.8...

I just finished watching a hawkins program about time travel that theorized that the faster an object travels through space, the slower it moves through time. The example involved a trip to Alpha Centauri at 99.9% light speed. He claimed that although the trip would only take a few years to...

Imagine the following experiment: Scientists have made a machine that can create a traversable wormhole and can also accelerate one end at near the speed of light and bring it back. A time machine. Suppose the dilation between the two ends is 10 years. As soon as the experiment brings...

The title is the best way I could group this thought. And the following is most likely sloppy so I do apologize. I get the 'feeling' (subjective I know), that the measurement effecting the outcome i.e. only being able to measure position over velocity, collapsing wave functions, etc... comes...

Homework Statement a) Find the probability that a molecule will travel a distance at least equal to the mean free path before its next collision. b)After what distance of travel since the last collision is the probability of having suffered the next collision equal to 1/2? Homework...