Travel Definition and 994 Threads

do all mass less particles travel at the speed of light?

I need your help to figure it out if the following thought experiment makes sense. Imagine two points in space at the same distance from Earth, 100 light years. At one point a previously unknown supernova explodes; we observe it’s bright light in the sky for several months, and after that it...

Homework Statement Two trains trqvel on Paralel tracks in the same direction. Train 'A' has a length of 1 km and traveling at 50 m / s. Train 'B' has a length of 0.5 km and starts at just the moment when the rear of the train 'A' passes at the front of the train 'B'. Train 'B' has an...

When you shoot a single photon, wouldn't the oxygen, and other atoms in the air we breathe move the light off it's trajectory. Won't the light hit any atoms or bend away from the atoms. Does light bend in air? Does it bend to avoid striking the atoms? How do we see straight lines, how do we...

Homework Statement [PLAIN]http://vctson.com/temp/curve.jpeg Find the curve y = f(x) so that the ball travels from A to B in minimum time? Thanks!

Homework Statement Plans are made to send a spaceship from Earth to a nearby star 10 light-years away and at rest with respect to Earth. The light support systems within the spacecraft will last for a year. (a) what is the minimum speed of the spacecraft relative to the Earth-star system if...

Using information and calculators I found online, I have put together a series of tables illustrating the energy, fuel mass, and time requirements (both Earth and ship time, at 1 g acceleration) for a spacecraft to reach various percentages of light speed...

Today, October 6th 2011 I received my first official reminder about the electoral register form I obviously didn't complete on 15 October 2011 from the Registrar. He further wrote Well after trying unsuccessfully to apply Einsteins theory of simultainity to the concept of instantaneous...

If time travel is possible does it allow for violatation of the no clone theorem? thanks

The main, or one of the main, arguments I hear about neutrinos flying faster than light is that it would violate casualty aka. time travel. The Light Cone is supposed to be broken, in that case, and impossible things happen. But, even if neutrinos do travel faster than c - all we need to do...

Hi I'm new and an idiot so please don't burn me, I wouldn't have come to a specialist forum if I could have found the answer in a more mainstream place. Anyway, can somebody please explain to me in layman's terms why, if one could travel faster than the speed of light, they'd go back in time...

Homework Statement A car accelerates uniformly from rest to a speed of 23.2 km/h in 5.4s. Find the distance it travels during this time. Answer in units of m. Homework Equations \Deltax = 1/2(vi + vf)t vf = vi + at vf2 = vi2 + 1/2 at2 The Attempt at a Solution I have used...

Two cars start from rest at a red stop light. When the light turns green, both cars accelerate forward. The blue car accelerates uniformly at a rate of 5 m/s2 for 4.3 seconds. It then continues at a constant speed for 9.7 seconds, before applying the brakes such that the car’s speed decreases...

Hey i am new in this forum and just want to share my thoughts with you guyz at the recent finding at CERN . If the findings of CERN experiment are correct then does it means that time travel into the past is proved WRONG.? Because according to relativity theory if something moves faster...

Hi , It is experimentally shown that neutrinos can travel faster than light http://www.nature.com/news/2011/110922/full/news.2011.554.html What are the implications of that discovery ?

Neutrino discovered to travel FASTER than LIGHT? http://online.wsj.com/article/AP58b5aed0a77c45ddb163d90951b36b35.html I don't know if this is old news, but I do know that the news often gets information wrong is this correct has anyone heard of this? Apparently neutrinos were discovered to...

Oh my. <facepalm> http://www.livescience.com/16183-faster-speed-light-physics-breakthrough.html

Assuming it were possible, how would you go about it? Lightspeed spaceship? Wormhole? Superman gravitational reversal?

Everyone has heard of the space elevator using a cable(s) that attaches to a geosynchronus satellite. Now trying to lift things is always a very energy expensive process, since just making a payload weightless cost energy and you get zero velocity and travel. Also how fast could an elevator...

Why does faster than light travel or propagation mean time travel backwards to violate causality?

Hello, Is it true that the event horizon will destroy anyone who was able to enter a wormhole before exiting to another location? And is it also true that if fed the correct exotic matter, a wormhole could be opened large enough to travel through? If so, could a wormhole exist in close enough...

can we hear the sound of our steps in moon?

And how is it possible or not possible? Can you also take into consideration the new advancements in physics. thanks

Homework Statement A record of travel along a straight path is as follows: (a) Start from rest with constant acceleration of 3.95 m/s 2 for 16.5 s; (b) Constant velocity of 65.175 m/s for the next 0.789 min; (c) Constant negative acceleration of −10.4 m/s 2 for 3.52 s. What was the total...

note: I will be brief, I previously attempted to post this thread and was logged out while writing a wall of text, I do not have the energy to get it all down again. - Is near light speed space travel theoretically viable due to time dilation (traveler covering light years while potentially...

Hi yall, I know FTL is impossible so please don't flame,but if you were on a rocket that just so happened to be traveling at or faster than 3 x 10^8 m/s relative to say Earth, and they shined a powerful laser parallel to your path, would the beam of light still zoom past you at 300,000 km/s? Or...

This is a followup to another thread I started, on the current status of Newton's theory of gravity as compared with Einstein's. I asked this further question there in the last reply I made, but nobody answered, so I started this thread to ask it here. Newton's theory as I said there is still...

Why can't we time travel in backward?? Consider a person traveling in space (Straight road) O <|> /\ _______________________________________________ 0 Km 12 Km He travels at 100 m/s and completes 12km in 2...

Hi! First of all, I just want to say that I don't know much about general relativity. But my question concerns an example often found in textbooks about special relativity. On to my question. I have heard several times that one can travel forward in time (earth-time) by leaving earth...

Force is a push or pull. Is it just the transfer of energy from one body to another? If yes, why does it mostly result in the acceleration of the body? If no, then how does force travel?

How fast must we go to travel to another galaxy?

Is there any limit on how far light can travel -in a vacuum that is.

bacteria space travel ! If a bacteria was traveling through space at the speed of light would the cells divide at a constant or relative rate. Also would space travel effect the number of divisions..

This isn't a homework question. My friend stumbled upon his textbook that stated since the circumference of the globe is 2*pi*r, the velocity of someone who "ran all the way around" would be v = (2*pi*r)/t. However, isn't the displacement zero? And velocity = displacement/time? so is this...

So I'm just getting into physics to research for a short story idea I've had for a while, but I've got a few questions I'm having difficulty finding an answer to. As the universe expands, does space expand? Like, if someone took a marker and drew a small star on a balloon and then inflated...

Hi I am new, I've read the FAQ's and none of them seem to help. Its a classic question I know but I can't seem to find a full answer. I understand that light is part of the electromagnetic spectrum I also understand that light acts as both a particle and a wave. I think I understand the...

How does light stay in motion? Why does it travel at it's speed? Does it act as a particle or wave? Any links I can read information from will be appreciated !~

http://www.physorg.com/news/2011-07-hk-physicists-photons.html I thought to the future was possible, but not anymoerÉÉ

First off, I'm new here so if this is in the wrong section I apologize. Now to the question: As dumb as this may sound to people that know more about physics then me (I'm a med student but I find myself reading about physics time to time) it makes perfect sense in my head (due to lack of...

Homework Statement A man brushes the end of a rope that sends a pulse up the rope to the fixed end of the rope and back down to the bottom. How long does it take the pulse to make the trip from the bottom of the rope, to the top, and back? Let the length of the rope be l and its mass m...

Writing Sci-fiction Graphic Novel need advisement in "space travel" I've used VASIMR rockets as a reference and cited them as precursors to what now allows "rapid stellar travel" at say Earth to Mars in forty eight hours. Any advice on how this could be at least theoretically possible?

Hi. This seems like the right place to discuss how the universe is built. So, answer me this: How would the universe react to Time Travel? Time Travel is (atleast to the extent of what I know) the activity which may cause most paradoxes. Paradoxes are weirdo nasty things, and the question...

There has been much discussion of time travel, but I haven't yet found an answer to a question I have. That is, what are the specific theories or factors that allow for the possibility of time travel? The issue has been discussed and debated many times on this forum and I'm not so much...

Why does a projectile sitting on the ground travel further than a projectile launched on a cliff? As per HyperPhysics it said that sitting on ground a projectile at 15m/s and 40 degrees above the horizontal would travel +22 m but if you put on top of a 3 m high cliff, the range would be...

hey guys, I'm new to this forum so i don't know if this has been already asked before i saw this equation on special relativity explaining why objects with mass cannot travel at the speed of light E = mc^2/(1-(v^2/c^2))^0.5 ( hard to write on a computer. view the attachment for the...

So when humans talk of space travel, we imagine these horribly complex and sanitized capsules or small spacecraft with people in big spacesuits. The vehicles are made of super lightweight material with extraordinarily high-tech components and if the slightest thing goes wrong, the thing could...

so they say we can't travel back n time because it would create a paradox. Theres a line of thought that's says it may be possible i we select the history that does not cause a paradox. However it seems to me that quantum physcics also says that all historys exsist until we collapse the wave...

In trying to understand electricity I thought of the following: If I set up a wire one light year long, stretching out into space ½ a light year out and ½ a light year back, and connected a series of light bulbs all the way around the wire, and then connected a battery (large enough to handle...

Does quantum entanglement allow information to travel faster than light? http://en.wikipedia.org/wiki/Faster-than-light if you scroll down to quantum mechanics.

As I have read, a clock in a spaceship approaching the speed of light will appear to slow down in time from the point of view of an outside stationary observer. Does the direction of travel of the spaceship relative to the observer have an effect? If it is traveling towards the observer it seems...