Bend Your Mind With Special Relativity

Ever dreamed of traveling nearly as fast as light? Zipping across the universe to check out the sights seems like it could be fun. But, not so fast. There are a few things you should know before you jump into your rocket. At near the speed of light, the day-to-day physics we know on Earth need a few modifications. And if you’re thinking Albert Einstein will be entering this equation, you’re right!

We live our daily lives using what scientists call Newtonian physics, as in Isaac Newton, the guy who had the proverbial apple fall on his head. Imagine that you are on a sidewalk, watching your friend walk toward the front of a bus as it drives away. The bus is moving at 30 mph. Your friend walks at 3 mph. To you, your friend is moving at 33 mph — you simply add the two speeds together. (The 30 mph the bus is moving plus 3 mph that your friend is moving inside the bus.) This is a simple example of Newtonian physics.

However, imagine that your friend on the bus turns on a flashlight, and you both measure the speed of its light. You would both measure it to be moving at 670 million mph (or 1 billion kilometers per hour) — this is the speed of light. Even though the flashlight is with your friend on the moving bus, you still both measure the speed of light to be exactly the same. Suddenly you see how Einstein’s physics is different from Newton’s.

This prediction was a key part of Einstein’s special theory of relativity: The speed of light is the same for any observer, no matter their relative speed. This leads to many seemingly weird effects.

Before talking about those surprising effects, it’s good to take a moment to talk about point of view. For the rest of this discussion, we’ll assume that you’re at rest — sitting in one spot in space, not moving. And your friend is on a rocket ship that you measure to be traveling at 90% the speed of light. Neither of you is changing speed or direction. Scientists give this a fancy name — an “inertial frame of reference.”

With the stage set, now we can talk about a couple of super-weird effects of traveling near the speed of light. Relativity messes with simple things like distance and time, doing stuff that might blow your mind!

Let’s say you have a stick that is 36 inches long (91 centimeters). Your friend on the rocket doesn’t know the stick’s length, so they measure it by comparing it to a ruler they have as they zoom past you. They find your stick is just 16 inches (40 centimeters) long — less than half the length you measured! This effect is called length contraction. And if they were moving even faster, your friend would measure your stick to be even shorter. The cool thing about relativity is that both of those measurements are right! We see these effects in particle physics with fast-moving particles.

If your friend was traveling to our nearest neighbor star, Proxima Centauri, how far would they think it was? From Earth, we measure Proxima Centauri to be 4.2 light-years away (where one light-year is the distance light travels in a year, or about 5.8 trillion miles). However, your friend, who is traveling at 90% the speed of light in the rocket, would measure the distance between Earth and Proxima Centauri to be just over 1.8 light-years.

That’s just length … let’s talk about time!

Now let’s say you and your friend on the rocket have identical synchronized clocks. When your friend reaches Proxima Centauri, they send you a signal, telling you how long their trip took them. Their clock says the trip took just over two years. Remember, they measure the distance to be 1.8 light-years. However, you would see that your clock, which stayed at rest with you, says the trip took 4.7 years — more than twice as long!

This effect is called time dilation — time on moving clocks appears to tick slower.

None of this accounts for your friend accelerating their rocket or stopping at Proxima Centauri. All of this math gets more complicated if you and your friend were speeding up, slowing down, or changing directions. For instance, if your friend slowed down to stop at Proxima Centauri, they would have aged less than you on their trip!

Now you’re ready for a few tips on near-light-speed travel! Watch the video below for more.

Now, if you need to relax a bit after this whirlwind, near-light-speed trip, you can grab our coloring pages of scenes from the video. And if you enjoyed the trip, download a postcard to send to a friend. Finally, if you want to explore more of the wonders of the universe, follow NASA Universe on Facebook and Twitter.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

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4 years ago

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GAMPER & DADONI - Claptone - No Eyes feat. Jaw (GAMPER & DADONI Remix)

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Planispheric Astrolabe This is a paper reconstruction of one of the four brass planispheric astrolabe by well known 15th century German astronomer, Georg Hartmann. It was … Planispheric Astrolabe

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4 years ago

NASA Spotlight: Christina Hernandez, NASA Mars 2020 Rover Instrument Engineer

“I was in love with the beauty of space. It was my introduction to appreciating the beauty of complex, chaotic things—black holes, giant gas planets, or killer asteroids—that got my imagination riled up.“ -Christina Hernandez

Christina Hernandez, a space enthusiast and self-proclaimed nerd, is an aerospace engineer at our Jet Propulsion Laboratory in California where she works as an instrument engineer on our newest rover mission – Mars2020. The Mars2020 rover is a robotic scientist that is launching to the Red Planet next year. If you would like to launch to the Red Planet as well, you can Send Your Name to Mars along with millions of other people! Christina’s job is to make sure that the instruments we send to the Martian surface are designed, built, tested and operated correctly so we can retrieve allll the science. When she isn’t building space robots, she loves exploring new hiking trails, reading science fiction and experimenting in the kitchen. Christina took a break from building our next Martian scientist to answer some questions about her life and her career:

If you could go to Mars, would you? And what are three things you’d bring with you?

Only if I had a round trip ticket! I like the tacos and beach here on Earth too much. If I could go, I would bring a bag of Hot Cheetos, a Metallica album, and the book On the Shoulders of Giants.

If you could name the Mars2020 rover, what would you name it and why?

Pilas, a reference to a phrase my family says a lot, ponte las pilas. It literally means put your batteries on or in other words, get to work, look alive or put some energy into it. Our rover is going to need to have her batteries up and running for all the science she is going to be doing! Luckily, the rover has a radioisotope thermoelectric generator (RTG) to help keep the batteries charged!

What’s been your most memorable day at NASA?

It’s been seeing three of the instruments I worked on getting bolted and connected to the flight rover. I’ll never forget seeing the first 1’s and 0’s being exchanged between the rover compute element (RCE), the rover’s on-board brain, and the instruments’ electronics boxes (their brains). I am sure it was a wonderful conversation between the two!

It’s a long journey to get from Earth to Mars. What would be on your ultimate road trip playlist?

Metallica, The Cure, Queen, Echo and the Bunnymen, Frank Sinatra, Ramon Ayala, AC/DC, Selena, Los Angeles Azules, ughhhh – I think I just need a Spotify subscription to Mars.

What is one piece of advice you wish someone would’ve told you?

Take your ego out of the solution space when problem solving.

Do you have any secret skills, talents, or hobbies?

I love reading. Each year I read a minimum of 20 books, with my goal this year being 30 books. It’s funny I increased my goal during what has definitely been my busiest year at work. I recently got into watercolor painting. After spending so much time connected at work, I started looking for more analog hobbies. I am a terrible painter right now, but I painted my first painting the other day. It was of two nebulas! It’s not too bad! I am hoping watercolor can help connect me more to the color complexities of nature…and it’s fun!

What’s a project or problem that you would love the ability to tackle/work on?

I would love to work on designs for planetary human explorers. So far, I have focused on robotic explore, but when you throw a “loveable, warm, squishy thing” into the loop, its creates a different dimension to design – both with respect to operability and risk.

Thanks so much Christina! The Mars2020 rover is planned to launch on July 17, 2020, and touch down in Jezero crater on Mars on February 18, 2021.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

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Prime Video: Hanna - Season 1

In equal parts high-concept thriller and coming-of-age drama, HANNA follows the journey of an extraordinary young girl raised in the forest,

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5 years ago

Our Innovation Hub has officially sent over 500,000 pages to the National Archives catalog! The 500,000th page is a form that Antonio Dardell filled out to apply for an increase in his Civil War veteran’s pension.

Antonio Dardell is one of the small number of Chinese American soldiers who fought in the American Civil War.

Dardell had been adopted as a young boy by an American whaling ship captain, and brought to Connecticut. He enlisted in the 27th Connecticut Infantry Regiment at age 19. After the war he worked as a tinsmith, and in 1880 he became a naturalized citizen, showing his honorable discharge certificate in lieu of a Declaration of Intent.

This pension file was scanned as part of a two-week project by two citizen scanners who were interested in digitizing records relating to Asian American history. In addition to Antonio Dardell’s pension, the citizen scanners also worked on his Compiled Military Service Record (CMSR), and the CMSRs and pensions of other Chinese American soldiers.

Thank you to everyone who has volunteered their time in the Innovation Hub working to scan documents that are now part of our online Catalog (https://catalog.archives.gov). You are making history more accessible! Learn more about the Innovation Hub: https://www.archives.gov/innovation-hub

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