Speed of Light

The refractive index indicates how much light is slowed down as it travels through a medium compared to its speed in a vacuum. Since light travels more slowly in a medium than in a vacuum, the refractive index of the medium is always greater than 1.

Logically incoherent. Who said you need to use the entire universe to measure

the speed of anything ? Simply define your own start and end points, and then

measure the time light takes to travel between them. The points can be as

mundane as two opposite walls of the restroom in your laboratory.

This phenomenon is called refraction. When light travels from one medium (such as air) to another medium (such as water), it changes speed and direction, causing objects to appear bent or distorted at the boundary between the two mediums.

A convex lens can change the behavior of light waves by refracting them, causing the light to converge and creating a magnified image of an object. This magnification effect can make an object appear larger than its actual size when viewed through the lens.

It has to do with the nature of space and time or more accurately, the nature of spacetime. It turns out that both space and time are relative and how much space and time you experience depends on your frame of reference.

For example, imagine you were to travel in a spaceship at 99% the speed of light to a distant star that was a 100 trillion kilometers away .

Those left at home would see the distance you traveled to be 100 trillion kilometers and would consider the time it took you to be about 10 years.

However, you in the spaceship would only measure the distance to the star to be 14 trillion kilometers instead of 100 trillion kilometers and you would think it only took you 1.4 years to travel there instead of 10 years.

If you traveled even faster at 99.99% the speed of light you would measure the distance to be 1.4 trillion kilometers instead of 14 and you would think it only took you 0.14 years instead of 1.4.

If you traveled even faster at 99.9999% the speed of light you would measure the distance to be 0.14 trillion kilometers instead of 1.4 and you would think it only took you 0.014 years instead of 0.14, and so on.

The closer to the speed of light you travel the shorter the distance becomes for you and the less time it takes you.

As you can see "space and time becomes less and less" for you in the spaceship relative to us here on the earth.

What it comes down to is that different people see space and time differently, depending on the "frame of reference" from which they are looking at things.

Note however that it would be impossible for you to travel at exactly the speed of light because it would theoretically take you an infinite amount of energy to get up to that speed. Light can do it because it has no "rest mass".

For light when it travels from one point to another at the speed of light, from its point of view, it experiences no passage of time and there is no distance between the two points.

At lower speeds, the kinetic energy is 1/2 mv2 (1/2 times mass times speed squared), but since we are approaching the speed of light, the more accurate formula is (note: I am using root() to indicate the square root):

mc2(1 / root(1 - (v/c)2) - 1), which in this case is (mass in kilograms) x (300,000,000 m/s)2 x (1 / (root(1 - 1/4)) - 1) = mass x 9x1016 x (1 / (root(3/4)) - 1) = mass x 9x1016 x (1 / 0.866 - 1) = mass x 9x1016 x (1.155 - 1) = mass x 9x1016 x 0.155 = 1.395 x 1016 (Joule for every kilogram).

Note 1: This is the kinetic energy content of the spaceship, and the minimum amount of energy required to accelerate it to that speed; if any energy is wasted, the total needed would of course be more.

Note 2: The standard (non-relativistic) formula is 1/2 x mass times (150,000,000 m/s)2 = 1.125 x 1016. This is somewhat lower than if you use the correct relativistic formula. The more you approach the speed of light, the larger will be the discrepancy between the relativistic formula and the classic formula. At less than 1% of the speed of light or so, the discrepancy is so small that it isn't worthwhile to use the more accurate (and more complicated) relativistic formula.

The speed of light in indium is approximately 197,000 km/s, which is slightly slower than the speed of light in a vacuum, which is about 299,792 km/s. This difference is due to the interaction of light with the atomic structure of the material.

Trough vacuum, it'd be 2.997.924.562 metres/second;

Through air, it'd be 2.997.025.450 metres/second;

both round to 3.000.000.000 metres/second, or 300.000 kilometres/second.

Particles that have no mass, such as photons, travel at the speed of light in a vacuum. These particles exhibit wave-particle duality and can behave both as waves and particles. Light, as a form of electromagnetic radiation, also travels at the speed of light.

A laser produces coherent light, which means the light waves have the same frequency and are in phase with each other. This results in a focused and intense beam of light with high energy density.

It is neither a scalar or a vector? Scalar and vectors are used to describe quantities, for example scalars include distance and mass, while vectors include weight and velocity. We do not say that a situation is a scalar or a vector.

The energy required for a spaceship to travel at 90 percent of the speed of light would be substantial due to the relativistic increase in kinetic energy as speed approaches the speed of light. The energy required can be calculated using Einstein's mass-energy equivalence formula, E=mc^2. The exact amount of energy would depend on the mass of the spaceship and would be calculated as the difference in energy between its rest mass and its kinetic energy at that speed.

Ibn al-Haytham (965 in Basra - c. 1040 in Cairo) a Muslim scientist, proved that rays of light travel in straight lines, and carried out various experiments with lenses, mirrors,refraction, and reflection. He was also the first to reduce reflected and refracted light rays into vertical and horizontal components, which was a fundamental development in geometric optics.Book of Optics.(Ibn al-Haytham)

The speed of light in a vacuum is 299,792 kilometers per second. Thunderstorms generally travel at about 20-30 miles per hour. Lightning can travel at different speeds depending on atmospheric conditions, but typically moves at around 220,000,000 mph.

The line is : the word ; Equal

Yes. Since it has a temperature, it is giving off infra-red radiation. Some parts of it (molten lavea) are so hot that they give off visible light as well.

The distance to Ceres varies depending on the relative positions of Earth and Ceres in our orbits. As of April 25, 2010, at 3:07 PM PDT, Ceres is at a distance of 2.158218 AU, where each AU is about 500 light-seconds. (One AU is the average distance between the Sun and the Earth.)

So Ceres is currently 1079 light-seconds away.

The orbit of Ceres around the Sun is an ellipse with aphelion of 2.98 AU and perihelion of 2.55 AU. When the Earth is on one side of the Sun and Ceres is on the other, our distance apart is about 3.98 AU, and when Ceres and the Earth are closest together, we are only about 1.55 AU distant.

You can download the free open-source planetarium program Stellarium to see a representation of the sky and calculate the distance to any astronomical object in its database. And if you can see it, it's in there!

Anything that has any mass when it's at rest would have infinite mass at the speed of light.

Light itself does not have weight because it consists of massless particles called photons. However, when light interacts with matter, like hitting a surface, it can exert pressure that has an impact.

Although the majority of mushrooms don't, believe it or not, there are 71 species of mushrooms that are bioluminescent- they glow or give off a light.

Scientific America has a great article about the most recent discovery last year, of 7 species of fungi that glow.

Intensely cool question!

No, both light in air and radiation from a microwave oven travel at the speed of light in a vacuum, which is approximately 299,792 kilometers per second. Therefore, they both travel at the same speed.

When a light ray travels from glass into water, it changes speed and bends towards the normal (perpendicular line) at the glass-water interface due to the difference in optical density between the two mediums. This phenomenon is known as refraction. The extent of bending is determined by the refractive indices of the materials involved.