tu regere imperio populos, Romane, memento

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.

This post is the first in a series covering Japanese adjectives! After you read this post, you will know how to tell the difference between い and な adjectives, as well as how to use them to modify nouns. To understand this post, you don’t need to know ANY Japanese, except how to read hiragana. I hope you find this post helpful in your Japanese learning journey!

We’re set to launch the Mars 2020 Perseverance rover mission from Cape Canaveral, Florida, on July 30. The rover is loaded with scientific instruments and advanced technology, making it the largest, heaviest and most sophisticated vehicle ever sent to the Red Planet.

What is Perseverance’s mission and what will it do on Mars? Here are seven things to know:

1. Perseverance draws on the NASA – and scientific – spirit of overcoming challenges

Not only does it have to launch during a pandemic and land on a treacherous planet, it has to carry out its science goals:

Searching for signs of past microbial life

Mapping out the planet’s geology and climate

Collecting rock and other samples for future return to Earth

Paving the way for human exploration

We chose the name Perseverance from among the 28,000 essays submitted during the “Name the Rover” contest. Because of the coronavirus pandemic, the months leading up to the launch in particular have required creative problem solving, teamwork and determination.

2. Perseverance builds on the lessons from other Mars rovers

In 1997, our first Mars rover – Sojourner – showed that a robot could rove on the Red Planet. Spirit and Opportunity, which both landed in 2004, found evidence that Mars once had water before becoming a frozen desert.

Curiosity found evidence that Mars’ Gale Crater was home to a lake billions of years ago and that there was an environment that may have sustained microbial life. Perseverance aims to answer the age-old question – are there any signs that life once existed on Mars?

3. Perseverance will land in a place with high potential to find signs of ancient life

The rover will land in Jezero Crater, a 28-mile wide basin north of the Martian equator. A space rock hit the surface long ago, creating the large hole. Between 3 and 4 billion years ago, a river flowed into a body of water in Jezero the size of Lake Tahoe.

4. Perseverance will also collect important data about Mars’ geology and climate

Mars orbiters have collected images and other data about Jezero Crater from about 200 miles above, but finding signs of past life will need much closer inspection. A rover like Perseverance can look for those signs that may be related to ancient life and analyze the context in which they were found to see if the origins were biological.

5. Perseverance is the first leg of a round trip to Mars

This is the first rover to bring a sample-gathering system to Mars that will package promising samples of rocks and other materials for future return to Earth. NASA and ESA are working on the Mars Sample Return campaign, so we can analyze the rocks and sediment with tools too large and complex to send to space.

6. Perseverance will pave the way for human exploration of the Red Planet

Two packages – one that helps the rover autonomously avoid hazards during landing (TRN) and another that gathers crucial data during the trip through Mars’ atmosphere (MEDLI2) – will help future human missions land safely and with larger payloads on other worlds.

There are two instruments that will specifically help astronauts on the Red Planet. One (MEDA) will provide key information about the planet’s weather, climate and dust activity, while a technology demonstration (MOXIE) aims to extract oxygen from Mars’ mostly carbon-dioxide atmosphere.

7. You get to ride along

Perseverance and other parts of the Mars 2020 spacecraft feature 23 cameras, which is more than any other interplanetary mission in history. Raw images from the camera are set to be released on the mission website.

There are also three silicon chips with the names of nearly 11 million people who signed up to send their names to Mars.

And you can continue to follow the mission on Twitter and Facebook. 

Approaching this problem we are going to use the Schrödinger equation (suprise) - in this case we’re going to need it in its time independent form in one dimension.

As always when you have a derivative of a function which is the function itself with a constant in front, you can imagine that the constant comes from applying the chain rule. As a result your ansatz is the following:

Because we have a free particle there are no boundary conditions and thus no restrictions on the energy the particle has. It can adopt any energy.

To get the wave function depending not only on space but also on time we just apply this time evolution operator:

Now the key is checking the units of this fraction! hbar has the unit of action, i.e. Js=kg*m^2 / s. k is in units of m^-1. Putting everything together gives us units of velocity! Consequently the shape of the wavefunction does not change in time because of this constant velocity and any point on the function moves with this velocity in +x and -x direction. 

The solution of the Schrödinger equation for a free particle is a propagating plane wave which does not change its form in time - what does that mean? You cannot normalize this solution! And this really is a problem because a wave like this would have infinite energy - objects like that simply do not exist. 

Actually the only way to avoid this problem is to regard a free particle as a wave packet which is a continous linear combination out of the solution we got above with a definite range of k’s. Check it’s mathematical properties: It is a Fourier transformation! Fourier is always a huge help, haha.

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Intro:

Zarma is the most widely spoken language from the Songhai branch of the Nilo-Saharan family, with over 2.2 million speakers. It is primarily spoken in Niger and the surrounding countries, and is in fact the second most spoken language in Niger after Hausa. 

Phonology & Orthography:

Below is a chart showing Zarma’s alphabet and phonology. In addition to the vowels shown, Zarma also includes their nazalised counterparts, which are marked with a tilde above the vowel or by a following nasal consonant. Zarma is a tonal language with four tones: high, low, rising, and falling. You can listen to spoken Zarma here .

Grammar:

Zarma is an SOV language. Verbs do not have tense, but do have three aspects - the completive, the incompletive, and the subjunctive. Aspects are marked by a modal word before the verb, rather than by conjugation, and verbs without modal markers default to the completive aspect. Nouns are inflected for both number and form. The three forms are indefinite, definite, and demonstrative. 

Resources to learn more:

jan 3 // 7:52 a.m.

In 1952, at the height of his fame, F. R. Leavis entitled a collection of essays The Common Pursuit. It was his name for the academic study of literature. No one takes the idea seriously any more, but nor does anyone ask the obvious followup. If English literature is not a common pursuit—not a “great tradition,” to use Leavis’s other famous title—then what is it doing in the curriculum? What is the rationale for studying it? My own career (so called) suggests the answer. Namely: where there is no common body of knowledge, no common disciplinary conceptions, there is nothing that is indispensable.

—D. G. Myers, “Academe Quits Me”

“I won’t be available.”

Imagine you’re at work and your boss asks you to come in on Saturday. Saturday is usually your day off–coming in Saturdays is not an obligation to keep your job. Maybe you were going to watch a movie with a friend, or maybe you were just going to lie in bed and eat ice cream for eight hours, but either way you really, really don’t want to give up your day off.

If you consider yourself a millennial you’ve probably been raised to believe you need to justify not being constantly at work. And if you’re a gen-Z kid you’re likely getting the same toxic messages that we did. So in a situation like that, you might be inclined to do one of three things:

Tell your boss you’d rather not give up your day off. Cave when they pressure you to come in anyway, since you’re not doing anything important.

Tell your boss you’d rather not give up your day off. Over-apologize and worry that you looked bad/unprofessional.

Lie and say you’ve got a doctor’s appointment or some other activity that feels like an adequate justification for not working.

The fact is, it doesn’t matter to your boss whether you’re having open heart surgery or watching anime in your underwear on Saturday. The only thing that affects them is the fact that you won’t be at work. So telling them why you won’t be at work only gives them reason to try and pressure you to come in anyway.

If you say “I won’t be available,” giving no further information, you’d be surprised how often that’s enough. Be polite and sympathetic in your tone, maybe even say “sorry, but I won’t be available.” But don’t make an excuse. If your boss is a professional individual, they’ll accept that as a ‘no’ and try to find someone else. 

But bosses aren’t always professional. Sometimes they’re whiny little tyrants. So, what if they pressure you further? The answer is–politely and sympathetically give them no further information.

“Are you sure you’re not available?” “Sorry, but yes.”

“Why won’t you be available?” “I have a prior commitment.” (Which you do, even if it’s only to yourself.)

“What’s your prior commitment?” “Sorry, but that’s kind of personal.”

“Can you reschedule it?” “I’m afraid not. Maybe someone else can come in?”