Speed of light Definition and 1000 Threads

I was just wondering because as I understand it, there are different wave lengths of light. Also, if I understand it correctly, "light" is both a wave and a particle (photon). Now, I was a SONAR specialist in the Navy and one of the things we had to learn there was that sound waves...

Can we hold on..stand up inside spacecraft that close 99% speed of light and can our physical effort to hold on that speed?

question about speed of light? speed off light is a constant, so if theoretically we travel in empty space in a theoretical car on a theoretical road (no drag) with the speed of light and we turn on the head lights of the car, what would happen? The light form the head lights will stay on one...

Can this be doable in theory? Because who in the right mind would build this :) Let us imagine if we could build a steel rod, that has mass of 1 Kg, that has length about 300000 km. Yeah I know, impossible, but how about some material that can weight 1Kg or even 10Kg. But in space even 1000...

Hey everyone! So a guy at work today said "if you have a rocket with unlimited fuel(hypothetically speaking of coarse) at a constant accelleration, and was in space. It's velocity could reach like 99% the speed of light" I argued that it was not possible, as it approached the speed of light...

Slight theoretical question that i have difficulty wrapping my head around. Lets imagine a confined room traveling trough space at .9c on a line defined by points A and B. Let's say that in this room is a light source. If this light source is turned on than does the light inside the room...

In a frame S, there are two stationary objects A & B at a distance L in the x-direction. Object A is nearer to the observer than object B. Light will take time T to reach object B from A. Therefore in frame S, L/T = c In another frame S’, both objects A & B are moving at velocity v in...

Speed of light... It makes no sense to me that if the speed of light is always c...then in different mediums why this speed changes...?? I may have got it in a wrong way...But can anyone help me out in detail...(thanks)

Special relativity upended our normal conceptions of space and time by postulating that the speed of light was absolute for all observers. So rather than the absolute space and time of Newton, Einstein postulated an absolute speed of light, which by necessity leads to a malleable space and time...

99% The Speed of Light?? 1. if we move at this speed time is slow for us so what about the outer world does it seems faster to us? 2. people say that space also contracts in the direction so if we move at this speed for long time then will it contract constantly or will it just stop this...

I was recently watching part 1 of the Nova special The Elegant Universe based on Brian Greene's book of the same name. It was mentioned that through Einstein we learned that Gravity travels at the same speed of light. What relationship exists between Gravity and Light that makes them travel at...

How does time and space appear to a photon in vacuum (i.e. photon at at the speed of light)? Does time stop, when looked, from the frame of reference of a photon? What about space? Time-space are in a senses interchangeable/inseparable, so how does space-time appear to a photon? Does a...

If the speed of light were (slightly) different, how would that affect the chemical properties of atoms, if so?

I am trying to understand the implications of a fixed speed of light, mostly to explain it to my nieces and daughters. The distance to Aldebaran is 65 light years. I understand that means that it's distance is equal to the distance that light would travel in a vacuum in 65 years. But how much...

I've read a lot about special relativity, and what i don't understand is that speed of lights is the highest speed that a particle can reach. If we look to this simple experiment, i want to show, maybe you will understand better my thoughts. We are moving inside a car with a speed of 100...

I mean to say that can the speed of light differs in various media? Can we do any thing to change or alter speed of light? According to the theory of varying speed of light (VSL), the speed of light in the earlier satges of university were different from what they are today? How is this...

What makes the speed of light a constant. I read the FAQ on special relativity but still don't understand why c (speed of light) exists as a constant. It's like a rule like many others, why do they exist? Is there a part of space-time that limits this speed. Why are all the photons that ever...

If observed time approaches 0 at the speed of light, does that mean the distance one travles at the speed of light is infinite? Since speed = distance/time, does this mean that, at the speed of light C= infinity/0 which = 0? There then appears to be no speed at the speed of light. Does this...

I don't see how we can say the speed of light is X value. Here's why: Imagine you are driving 50mph then a cop comes up driving beside you at 50 Mph too. If he aims his gun out his window and clocks you it would read 0 Mph right? So to get your real speed he would have to look at his own...

obviouly the speed of light is constant when we are measuring it here on Earth however as mater speeds up time slows down. so if we were to measure the speed of light standing on a planet moving at the speed of light. what speed would we then be viewing light at? oh i do know that it is looking...

As I just registered as a member, I don't know if this question has been asked before on this forum, and I'm sorry if I'm asking it again. From what I understand, even if an object is moving away from light with a significant speed, the light would still approach that object as if it would be...

The speed of light is not constant in a non-inertial frame; the light accelerates with the acceleration of the observer in reverse direction. Consider the following problem: If a light pulse is created in an inertial frame at some time, t<0 (say t=-10); the light pulse moves at velocity c...

does the fact we are moving at 250km per second around our galaxy and 300km per second around other larger galaxys? have any effect on the speed of light? sure they arent that great compared to the speed of light but does it?

Just a little confused about amounts of redshift, I read somewhere about redshift and how some galaxies are moving at redshift 3 (I think), which was said to be at or near the speed of light, then later in the article is said a galaxy was found to be moving at redshift 6. I understand how the...

On "why massless particles move at the speed of light" It has come up a few times whether you can derive that massless particles must go the speed of light, strictly using SR. Bcrowell proposed a way that some argued against. I have a different tack for consideration. I recently derived...

If light always travels at the speed of light, and at the speed of light, time stops -- does this mean that light is eternal? In other words, if you were a particle of light, you would exist forever?

I've read that theorists predicted the big bang to expand faster than the speed of light. Is this true? If so, how can we say that nothing can travel faster than light today?

If a car is traveling towards you and turns on the lights the speed of light would be c, but if the car was traveling away from you and turned the lights on would the speed of light be c or less than c? I've tried to search this question, but it's not easy to describe in a search engine!

Normally when people talk about going near the speed of light they talk about Lorenz contraction and Time dilation, but to keep things simple they make one implicit assumption; there's nothing in the way. What if you are going 99.99% the speed of light and you crash into a planet? What if...

Doppler effect told us that the frequency and wavelength changed but not the speed of wave if the transmitter or receiver is moving. Could I interpret Doppler Effect as follow: Frequency/wavelength change for different observers, however, the speed of wave is constant for all observers. If...

Suppose we create an object which can cross the speed of light. Now, we can see an object when the light reflected from the object enters the eye. So, we can see the object moving at light only if the light from the object enter our eye. But its said every where that the speed of light is 3x10^8...

I am writing a storyline that has a battle scene that takes place in space. I was wondering, if one ship fires a small projectile at a speed nearing that of light, and it is emitting light, will the spaceship it is being fired at be able to see the shot for more than a few milliseconds before it...

Hi friends! I was reading a book in which it was mentioned that the speed of light does not changes if we move towards its source or move away from it. Now the question comes in my mind as follows; suppose a space shuttle is moving in space with velocity almost equal to that of...

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I always wanted to make a post about this, because it's kind of cool. Living in south Louisiana, hunting/trapping/fishing is a big part of the culture. This January, my dad's brother and his son were on a deer stand on a pipeline, and they saw a whitetail that was about 500 yards away...

Hi, i have tought of a something that i don't know if is it true. As far as i know speed of ligh is 300,000 km/s and it is about 8 minutes to reach the earth. Now when we look ate the other planets we are looking at sort of a delayed picture because of the time light needes to travel from that...

Hi when we derive time dilation and other consequences of relativity we base our idea to constant speed of light, and then we relate every other process to this. As I get we do it this way because speed of light is the speed of information and since we evaluate the processes in other reference...

You have a straight, light, hard, inelastic rod at hand. It's pretty long, long enough so that you can hold it out of your window and into your friends window at the other side of the street. The way you and your friend communicate is through morse code. You move the rod a distance x so that...

i am only a year 11 student so i don't know much about the Theory of relativity i just heard that if we can travel at the speed of light our time will be slower than the other so i am just wondering if we can travel at a negative speed of light that means that we can go back in time?

I have just come across the following quote by Nigel Calder:- "Light travels faster...toward the centre of gravity than away from it." How does one square this with the constancy of the speed of light?

Thought experiment. Let's imagine I'm on my spaceship moving in the void. For this example, I'm assuming my flight started on the Earth, where I could see the ground and landscape and thus I was able to tell that I was moving; however, without accelerating or decelerating, I progressively got...

Has anyone heard of the speed of light being derived from the Pythagorean Theorem? Obviously I'm referring to using the time dilation effect of motion. Frank

When I think of the speed of light, I imagine something moving really fast. Everyone knows that something moving fast hurts more than something moving slow. So why is something said to have "infinite" mass when traveling at the speed of light if the speed of light is a finite "measurable"...

Elctromagnetic induction by a solenoid moving with the speed of light?? The moment the magnetic field is generated, it should take some time to reach some distance. It cannot reach infinity instantly, it should have some speed, and that speed cannot be more than that of light. So let’s say that...

Ok, so I'm not a physicist by any means, and I don't actually understand the first thing about physics. So, I'm guessing that somebody's probably realized this before, and I just want to know the name of this "paradox" (i'm not even sure it's the right word) so I can read up on it. Here's the...

Is it possible to have an object bigger than the speed of light? What would an object that was hundreds of thousands light years across look like? Is there a point in which forces acting on it would make it impossible? Like gravity turning it into a black hole? I am interested in the Great...

You are one light year away from Earth, at rest in Earth's frame of reference. A flash of light is emitted from Earth. You begin to accelerate toward Earth. Does it still take exactly one year for the light to reach you from the time it was emitted?

Hey, I understand why if you watch someone they can never accelerate to the speed of light: their mass approaches infinity so the necessary impulse reaches infinity. But what about in the frame of reference of the person approaching the speed of light. They notice nothing unusual about their...

I can't figure out why it should. Here's what I'm thinking: - Light is affected by the gravity, and gravity is the interaction between masses, so surely light must have mass in some form. - Light has no mass, but has energy depending on the frequency of the photon. By E = mc^2, photons...

Often times I read in these forums that the sped of light is C in a vacuum, but is slower in non-vacuum environments. Every time I read this, I wonder if it is a misstatement. Doesn't light always travel at C, but gets interrupted by being absorbed and re-emitted countless times by intervening...