# How long would it take to cross the United States at the speed of light?

Light moves at a constant, limited speed of 186,000 miles per second. In one second, a person traveling at the speed of light would round the equator nearly 7.5 times. In comparison, a traveler in a jet aircraft traveling at 500 mph would cover the continental United States once every 4 hours. If we assume that the passenger-journeyer is using no more than 20 percent of his or her brain during the trip, then he or she could expect to sleep for 8 hours.

The speed of light is always measured between two fixed points: one located in New York City and another in Paris. Since 1927, when Einstein published his theory of relativity, scientists have used this phenomenon to send messages into space. As part of its program of scientific discovery, NASA builds upon this knowledge by sending spacecraft on far-reaching adventures across our galaxy and beyond.

In 1913, American inventor Albert Einstein published his famous paper on special relativity, which explained how the laws of physics and human perception are affected by moving at near light speed. Among other things, Einstein showed that the distance between any two objects can be doubled without actually doubling the time it takes for information to travel between them. This has important implications for people trying to send messages into space, as well as travelers on earth who want to use lights instead of engines to go faster than 300,000 miles per hour.

## How long would it take to travel around the world at the speed of light?

Light speed is approximately 670,616,629 miles per hour in miles per hour. You could go around the Earth 7.5 times in one second if you could travel at the speed of light. Because early scientists were unable to see light's mobility, they assumed it must move in an instant. But now we know that waves advance along the surface of any medium, such as water or glass, at a constant rate regardless of what's moving through it. At the speed of light, a wave can pass completely around a circle before the next wave comes along. So in reality, nothing happens instantly when you hit a high point on Earth's surface. Instead, there is a slight delay while the wave travels around the globe.

If you started traveling today and never stopped, you would need about 1,000 years to cover the distance around the Earth.

The fastest man-made object, the rocket, can only travel about 0.000001% of the speed of light. But even though rockets have reached speeds over 300,000 km/hour (186,000 miles per hour), they cannot travel faster than the speed of light. No matter how fast you go, light will always travel ahead of you. This is because light is a wave and like all waves it spreads out as it moves forward. If you tried to catch up with it, you would need to move into a region where space and time are not continuous.

## How far could we travel if we could move at the speed of light?

The speed of light in a vacuum is 186,282 miles per second (299,792 kilometers per second), and nothing can go faster than light. A journey between the Earth and Mars would take about eight minutes.

At this speed, it would take just over six months to reach the nearest star system, Alpha Centauri. From there, it would take another year and a half to reach Proxima Centauri, the closest star to our own solar system. It would then take another year and a half to get to another star, let alone another galaxy.

It might be possible for us to travel within our own galaxy, but not across any greater distance. Our galaxy is roughly 100,000 light years wide, which means that it would take about 30 million years to travel across it. The Milky Way Galaxy is only one of hundreds of billions of galaxies in the Universe. If you were to travel at the speed of light, you would never reach another galaxy or planet. Instead, you would continually circle around the same distant stars forever.

We are always being pulled by gravity towards the center of planets, stars, and galaxies. This is called "centrifugal force". It pushes us away from the point where the force is acting toward a point farther away.

## How far can a ray of light travel?

Light travels at a speed of 186,282 miles per second. As a result, light would travel 60 times that distance in a minute. 186,282 divided by 60 equals 11,176,920 miles per hour.

We can't travel at the speed of light because it would take too long to get anywhere. But we can come close! The average speed of airplanes is about half the speed of light (550,000 miles per hour). And some spaceships have traveled much faster than that.

At these speeds, only objects smaller than a cell phone can be traveled between the planets. Spaceships would need to be huge to hold a lot of people and supplies for such a long trip. And telescopes could be used to look at planets that are near stars so we know where to send out ships.

In conclusion, light can travel very far because it does not matter how big or small an object is, but it takes a lot of time to get there because everything else is moving along with it.

## How fast can we travel?

"Other than the speed of light, there is no actual practical limit to how fast humans may move," adds Bray. Light moves at a speed of one billion kilometers per hour. That's about 300,000 miles per second, or about 186,000 times the speed of sound.

But even traveling at that speed, it would take decades to reach the nearest star, says David J. Asher of the University of Wales in Cardiff. The closest star to Earth is Proxima Centauri, which lies about 4.24 light-years away. That's more than 30 trillion milesâ€”or half the distance from our planet to the next. Even if you could stay awake for your entire trip, you'd only make it as far as your last breath before you collapsed from exhaustion.

You might be able to travel faster than light if you used something other than human power. In science fiction, aliens and robots have traversed vast distances in seconds because they are not limited by the speed of human muscles or batteries. But here on Earth, we still depend on energy sources such as coal, oil, and natural gas that were created over millions of years by ancient organisms using the same basic process of photosynthesis. They converted sunlight into chemical energy that enabled them to grow larger brains and build more sophisticated tools over time.

## How fast would you have to travel to get around the world in 24 hours?

Assuming that the Earth's circumference is 24,000 miles and that the world rotates once every 24 hours, traveling down the Equator would necessitate a speed of 1,000 miles per hour (or 1,600 km). This is almost exactly the speed of sound - about 1,080 miles per hour (1,620 km). It is impossible to travel in aircraft any faster without exceeding the speed of sound.

Any attempt to reach such speeds by mechanical means would inevitably lead to failure. A machine this fast would need impractically large engines which could be operated for extremely long periods of time while consuming only a fraction of their total capacity. Such engines do exist but they are extremely complex and expensive.

The most efficient way to travel at a high speed is with a stream of air flowing over your body. The fastest human-powered vehicle ever recorded was set by American Eric Brown when he traveled 536.564 miles in one hour during a trial run in 1997. This was nearly 100 miles per hour! The United States Army has tested various designs of hypervelocity projectiles which can travel hundreds of miles per hour.

The problem with these missiles is that they are hard to control and very dangerous if they fail to detonate after reaching their target. However, their ability to travel far at high speeds makes them useful for attacks or defense against vehicles or aircraft at great distances.

##### Betty Mondino

Betty Mondino is a travel enthusiast who has been globe-trotting for years. She loves learning about the different cultures and how they are different from one another. Her goal is to experience as much of the world as possible while still finding time for herself!