My telescope for astrophotography in my light -folded San Diego yard was directed to a galaxy near the ground. My wife Cristina rose just as the first space photo broadcast to my tablet. He shone on the screen in front of us.
“This is a Pin Wheel galaxy,” I said. The name comes from its shape – although there are about trillion stars in this wheel.
Pinwheel Light has traveled to the universe for 25 million years – about 150 quarters miles – to get into my telescope.
My wife wondered, “Is the light tired of such a long journey?”
Her curiosity led to a thought about light. After all, why do you wear out and lose energy over time?
Let’s talk about the light
I am an astrophysicist, and one of the first things I have learned in my research is how light often behaves in a way that ignores our intuition.
Photo by the author Pinwheel Galaxy. Jarred Roberts
Light is electromagnetic radiation: basically an electric wave and magnetic wave combined and traveling through space time. It has no mass. This point is critical because the mass of the object, whether dust or spacecraft, limits the maximum speed it can travel through the space.
But since the light is without mass, it can achieve maximum speed limit in a vacuum – about 186,000 miles (300,000 kilometers) per second or nearly 6 trillion miles a year (9.6 trillion kilometers). Nothing to travel through space is faster. Looking at the perspective: over time you need to blink, the light particle travels around the perimeter of the Earth more than twice.
No matter how incredibly fast, the space is incredibly distributed. The light from the sun, which is 93 million miles (about 150 million kilometers) from the ground, takes a little over eight minutes to reach us. In other words, the sunlight you see is eight minutes.
Alpha Centauri, the nearest star with us after the sun, is 26 trillion miles away (about 41 trillion kilometers). So when you see it in the night sky, its light is just over four years. Or, as astronomers say, these are four light years.
With those huge distances in mind, consider Cristina’s question: How can light travel around the universe and lose energy?
In fact, some light loses energy. It happens when it collides with something like interstellar dust and is scattered.
But most of the light just goes and goes without interfering with anything. Almost always this is because the space is usually empty – nothing. So there is nothing.
When light travels unhindered, it does not lose energy. This can maintain that 186,000 miles per second for centuries.
The time has come
Here’s another concept: depict yourself as an astronaut at the International Space Station. You fly 17,000 miles (about 27,000 kilometers) per hour. Compared to something on Earth, your watch will mark 0.01 seconds more slowly within one year.
This is an example of time expansion – time to move at different speeds in different conditions. If you are moving really fast or close to a large gravitational field, your clock will mark more slowly than someone who is moving slower than you, or what is farther away from the large gravity field. Time, time is relative.
Now consider that light is inextricably linked to time. Picture sitting on a photon, the main particle of light; Here you will experience maximum time expansion. Every time on Earth is your clock at your speed, but the time of the reference frame will stop completely.
This is because the measurement time of “watches” is in two different places that run at very different speeds: the photon moves at the speed of light and relatively slow Earth speed around the sun.
Also, when you are traveling or close to the speed of light, the distance between where you are and where you go becomes shorter. That is, the space itself becomes more compact in the direction of motion – so the sooner you can go, the shorter your journey must be. In other words, for the photo, space is shredded.
It brings us back to my Pinwheel Galaxy photo. From a photon perspective, the Galaxy star spread it, and then one point in my backyard camera was absorbed at the same time. Because the space is bloated, the photo of the photon was extremely fast and infinitely short, a small part of a second.
But in our approach to the Earth, the photon left the galaxy 25 million years ago and traveled 25 million light -years through space before it landed on my tablet in my yard.
And there, on the cool spring night, his stunning image led to a charming conversation between a nervous scientist and his curious wife.
This article has been published from a conversation, non -profit, independent news organizations that provide you with facts and reliable analysis to help you give meaning to our complex world. It was written by: Jarred Roberts, California University, San Diego
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Jarred Roberts receives funding from NASA.