# How Fast Is The Speed Of Light

Einstein’s groundbreaking discovery about the fundamental nature of light, which was made in 1905, could be summarized with a surprisingly simple sentence that the speed of light remains continuous. What does that sentence translate to?

The answer is surprising, as it is not related to the actual speed of light, about 300,000 km in a second (186,000 miles per second) in a space “vacuum” of space. Instead, Einstein had an unexpected–and paradoxical–insight: that light from a moving source has the same velocity as light from a stationary source. For example, the beams of light coming from the lighthouse of a fast car’s headlights and the light sources on a supersonic jet are all traveling at the same speed according to all eyes–despite variations in the rate at which heads of these beams travel.

### Light in Motion

The Special Theory of Relativity is founded on Einstein’s realization that light’s speed doesn’t change when the light source is moved. While it seems logical to take to the rate of the light source and the speed of the beam of light to determine the overall speed, sunlight doesn’t work in this manner. However fast Einstein pedals his bike, the light from his headlight will always move at the same rate.

### Universal design

According to Cassibry However, Cassibry suggests another aspect to consider when discussing the possibility of items that move faster than light speed.

“There are parts of the universe that are expanding away from us faster than the speed of light because space-time is expanding,” He said. In this case, for instance, the Hubble Space Telescope has recently observed 12.9 billion years-old light coming from a distant star called Earendel. Since the universe continues to expand in every direction, Earendel is moving away from Earth and has been ever since its creation, meaning it is currently a billion light-years from Earth.

Space-time is growing, yet the space-time material remains within the limit of the speed of light.

### Almost As Fast As the Speed of Light?

We have covered the initial question and then modified it so that we could say, “What if you traveled almost as fast as the speed of light?” If that were the case, you’d experience some fascinating results. A well-known example is what physicists call time dilation, which is the term used to describe how time passes faster for objects moving quickly. If you took flight in a spacecraft traveling at 90 percent light speed, the speed of light for you would be cut in half. Your timer will only move forward 10 minutes. However, more than 20 hours would be passed to an observer on Earth (source: May)

There are also weird visual results. The most notable of these is known as aberration. It is the process by which your area of vision would be reduced into a tiny shape of a tunnel “window” out in front of the spacecraft. This is because photons (tiny particles of light), even those behind you, are coming in through the direction of forward motion.

Additionally, you will be able to observe an intense Doppler effect that causes light waves from the stars ahead of you to merge and make the stars appear blue. Stars behind would split and become to be red. The faster you travel, and the further away you go, the more severe the effect becomes until all visible light coming from stars directly in front of the spacecraft and the stars at its back are shifted out of the visible spectrum (the human eye can’t see the colors). If these stars move away from the wavelength, the stars appear to disappear into black or fade on the backdrop.

### How Fast Is the Speed of Light

Light speed, which scientists have studied and now expressed as a constant number, is referred to in equations as the symbol C. It is not a valid constant, but instead, the highest speed that can be achieved in a vacuum, that is, the speed of light in kilometers, which is close to 300,000 km/s, is manipulated through shifting media or quantum interference.

A homogeneous media, or straight substance, travels in a line at a relatively constant rate until it is diverted, refracted, reflected, or altered differently. This scientifically proven observation is not the product created by the Atomic Age or even the Renaissance; however, it was first propagated by the first Greek philosopher, Euclid, about 350 BC in his famous book Optica. The intensity of electromagnetic radiation (and the other radiations from electromagnetic sources) is in inverse proportion to squares of distance it has traveled. So, after traveling at a certain distance twice, its intensity decreases by a factor of four.

### How Fast Is the Speed of Light in Air and Water?

If light passing through the air is absorbed by a different like glass or water, the wavelength and speed of light are reduced (see Figure 2.); however, the frequency is not altered. Light travels approximately 300,000 km/sec in a vacuum. It is refractive with a refractive index of 1.0. However, the speed decreases to around 225,000 km each second for water (refractive index 1.3 See Figure 2.) and 200,000 kilometers per second in glass (refractive index of 1.5). With a diamond with a refractive index of 2.4, which is 2.4, the speed of light slows to a crawl (125,000 km/s), which is about 60% less than the highest speed in the vacuum.

Due to the vast distances that light takes in the outer galaxy space (see Figure 1.) and within the Milky Way, the expanse between stars is not measured in kilometers but light-years. This is the distance light could travel over some time in one year. Light-years equal 9.5 trillion kilometers or 5.9 trillion miles. The distance from Earth to the nearest star beyond our solar system, Proxima Centauri, is about 4.24 light years. In contrast, it is estimated that the Milky Way galaxy is estimated to be approximately 150,000 light-years in size, while the distance from The Andromeda galaxy is around 2.21 million light years. It means the light leaving the Andromeda galaxy 2.21 million years ago is only now arriving on Earth if it wasn’t scattered by reflecting bodies of the night or by refracting debris.

### Conclusion

Light speed is more than only a number. It’s an essential factor in understanding the workings of the universe. The astonishing rate of light and fundamentals that go with it have changed technological and science fields, allowing us to investigate the universe and develop revolutionary technology. While we contemplate the incredible speed of light, we get deeper insight into the universe’s nature and the boundaries of our knowledge.