Travel Definition and 994 Threads

Universe ?? So in books and pics online, you see the solar system in a single plane, if you want to travel great distances you use other planets gravity to swing you out there. What if we wanted to travel in ANY OTHER direction, could it be done? I heard that its not practical to send manned...

Hello; For something to travel at the speed of light, mass has to be zero. Light is a form of electromagnetic radiation, which travels at 299,792,458 m/s. Because it is a form of electromagnetic radiation, it is carried by the force-carrier particle, the photon. However, photons have a very...

I haven't been studying quantum mechanics for very long, and I've only just started reading about the path integral formulation, so I don't know many of the details yet, but I noticed something peculiar. The path integral formulation is possible because of the similarities of the Schroedinger...

Homework Statement Suppose rocket traveler Amelia has a clock made on Earth. She flies to and back from a planet 12 light-years away (as measured from rest with respect to Earth) from Earth at a speed of 0.6c. Every year she sends a signal to Earth. How many signals does Earth receive by...

Hi, How far does sound travel underwater, and more importantly does it travel further in water than in air? If so why? I know that sound travels faster through water than air for obvious reasons (density), and I intuitively assume further, but I cannot explain why. Any help is appreciated. Thanks

Hi,all, my problem is: Consider a 2-D square well potential, say length 2L, and when I put one particle into this well, Does this particles IMMEDIATELY know what wavefunction it should have? I am trying to consider, once the particle enter the (middle of the)well, the information takes at...

Hello guys, Sorry it is electrophoresis In electrophoresis is a similar electromotive force applied to all particles or are all particles accelerated at the same rate? What I mean is let's say if every particle gets 10N. F=ma and bigger particle would travel slower. So can't I include this...

Time Travel Question (from "A Briefer History of Time") I read the original "A Brief History of Time" and is now reading "A Briefer History of Time". :P There is a part about time travel that confuses me. Does anyone want to enlighten me using layman terms? (i am a mathematics major, not a...

Homework Statement So, higher frequency waves have greater energy than lower frequency waves. I know that around Earth the lower frequency waves penetrate best due to the higher frequency ones being absorbed by the atmosphere. However, in space do the higher frequency waves with more...

today's biology lession our teacher about cancer he said that if we travell somewhere by aeroplane, it's equal to take X-way 3 times i don't understand why we have radiation through traveling by aeroplane can someone explain to me, please thank you so　much

I have a relatively simple problem that I'm having trouble with. A ship is going at 0.90 c, over a distance of 80 light years. In my text the method for determining the time spent traveling is: 80 years + (0.1 * 80) = 88 years This method seems logical, at 0.9 of the speed of light this...

hey, I was just wondering if someone could give me an explanation about the following: 1. why, physically, does light travel at different speeds in different medium 2. why is the speed at which it travels through different media dependent of frequency, as is the case with dispersion...

Homework Statement A very small steel marble is shown rolling at a constant speed on a horizontal table. The marble leaves the table at L, falls, and hits the ground at P. This is illustrated in the diagram below which is drawn to scale. Calculate the time it took the marble to travel from N...

NOTE: This is NOT a homework question. I was reading a physics textbook for fun (doesn't everyone nowadays?) and could barely got through the first couple of page the chapter on electric currents because this question was not addressed in the book. Question 1) If you connect the negative and...

If time stops at the speed of light, how does light travel throught space and time? Example: The light from a star 12 light years away travels throught space and takes 12 years to get to earth. But in those 12 years the time on the star has stoped. Same goes for the light that is leaving...

Delayed choice in half silvered mirror or double slit For now, I am focussing only on the half silvered mirror: there are two paths/arms that are created. My question is: 1. If a detector/obstruction is placed on either of the two paths after the photon has passed but before its hit...

if a person speak something , the person just behind him is able to listen to that sound. so how does this disturbance traveled to the later persons??

Michio Kaku stated that current physics does not rule out the possibility of time travel even tho it would take comprimable measures to achieve it, such as the energy of a supernovae, my question is even if you can bend spacetime to that extreme to get to a planet with life on it, how are you...

Is SR-allowable time travel "future-only"? Relativity theory allows for the possibility of time travel to the future, according to time dilation as illustrating by the twin paradox. Wikipedia says, "it is currently unknown whether the laws of physics would allow backwards time travel." My...

Hey 1. If a person drive a car in 100 kph, while another person walks in 5 kph, will then time go slower for the driver? I saw a video on youtube about Einsteins theory of relativity. They said that the faster we travel, the slower time goes. So will then the person who walks be longer into...

Hello, I am attempting to write a script (for fun) which outlines a realistic scenario in which humanity travels to the stars within, say, 30 years. Given the short time frame, I'm thinking about using various forms of FTL travel. By my definition, FTL includes any means of getting from A...

Interstellar travel is always a problem in science fiction: you can't have the hero hibernate for millions of years whenever he or she wants to travel to another star, but it's annoying when spaceships just magically move faster than light. However, wouldn't length contraction from special...

Today in class we started talking about waves. I understand waves to be energy. This makes sense to me when thinking about sound waves, because the energy can travel from one particle to the next to travel; but I don't understand how things like electromagnetic waves can travel through a...

Special theory of relativity says that in the absence of an absolute reference, different observers may disagree on the time at which a particular event happened. With this knowledge, how do i explain time travelling? Every observer should be witnessing the same set of events (though their...

Two cars travel at the same speed of 105 km/h. One of the cars, a sleek sports car, has a motor that delivers only 35 kW of power at this speed. The other car's motor needs to produce 65 kW to move the car at this speed. Forces exerted from air resistance cause the difference. A) For...

Hi. I'm a student in AP Physics this year and we started the E&M portion this week and we learned about electric fields. I was watching MIT's OpenCourseWare in order to get more comfortable with the concepts. The lecturer said that charges do not follow electric field lines because of the...

If time travel is possible,is there any problem of universe revolving which would affect time travel,because as,Gödel was the first person who found solution to Einstein equations involving time travel,but he disappointed when astronomers told that universe is expanding,but the net spin of the...

Hi, I'm super new (registered one minute ago) because I tried yahoo answers, but realized no one there cares. So I came here (I've read a few random questions on my trek through the "internets") So, I'm just a kid, well I'm a sophomore in high school, but same thing. I have a pretty basic...

I'm an undergraduate physics student and whilst Quantum Physics is a fascinating area, it has me constantly asking questions - probably a good thing right? Now one of the fundamental principles to Quantum theory is the wave-particle duality of particles and light. I understand the history...

a question has been puzzling me for a while is : "is the distance traveled by a beam of light from point A to Point B in a flat space-time differs from the distance traveled by the same beam of light from the same point A and The Same point B but in a curved space-time ?" In other words ...

i understand what a sine wave is, as well as the hertz. but I am curious as to why all energy travels in a wave and not a straight line.

Hi Everyone, I have a simple question: How many arcseconds does the sun "travel" through the sky in one Tropical Year? Mark

I read that the Sun will become a red giant and destroy the Earth in about 5 billion years. If this is correct, is there any possible way that a vastly advanced alien civilization that exists in a galaxy 6 billion lights year away could ever reach the Earth and make contact with human...

I mean how would we ever do it in the first place? What rockets or propulsion units would we use?

anyone read or have opinions on The Quantum Physics of Time Travel by David Deutsch and Michael Lockwood? He talks about closed time like curves and if we followed them it would end up taking us to the past to participate in events, shake hands with former selves etc I was a little...

[FONT="Arial Narrow"][SIZE="2"][SIZE="2"]Imagine an event occurring on the moon that is not visible to the human eye, but with a high powered telescope it is easily viewed. Did the telescope see it happening in real time or did it see the event 1.32 seconds after it occured. Based on common...

I was reading about Eisteins theories and had a question. If light can not escape the gravitational pull of a black hole, then assuming that the black hole accelerates (at a constant acceleration) all matter and energy into its event horizon, then if the gravitational pull overcomes the speed...

Let’s say we have a spaceship capable of traveling at the speed of light, and a planet we can visit 50 light years away. From earth’s perspective if we can track the ship we would be able to see it was traveling at the speed of light and we would also see it has taken 50 years to complete the...

I am going to give write an essay about time travel. What does science say? What is the arguments for possibility and against possibility. And what does General Relativity Theory say about time travel? Theoretical possible, but not practically?

Or is it just that it can't be observed? This is a question that has been on my mind for some time, so i thought it worth asking here. Imagine the following scenario: Two spacecraft travel towards each other. Each travels at 0.6C relative to their point of origin (the points of origin being...

I was doing research on faster than light travel and a question popped into my head: what would be the side effects of faster than light speed travel? Any ideas?

I was doing research on fastaer than light travel, and I came across a chart that said that said that a starship can only travel ten times the speed of light until it occupies all points in space. (I understand that this is fiction, and is only possible in theory but I am still intreasted in...

Noob question: if an atom in a vacuum releases a photon does it have a direction? Does it propagate in a straight line? My answer was always "of course!" until I read Feynman's QED and now I'm confused. What I'm trying to get my head around is the idea that light "travels all possible paths...

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?

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 ...

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...

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...

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...

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...

[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...