Shadows are not always black!Shadows are absolutely fascinating…

Shadows are not always black!

Shadows are absolutely
fascinating to play around with.

In this Exploratorium demonstration
you can see that a black shadow is only a subset of shadows that can be
formed on the screen.

image

If you have multiple sources of light with different colors, then you can additively combine colors to get shadows of various shades.

image
image

In this case where you have multiple sources of light, only when the object blocks off light from all three colored light sources do you get a black shadow.

Since we do not deal with multiple colored sources of light on a daily basis, go ahead, give this simple experiment a try. It’s totally worth it!

Have a good one!

** Other FYP explorations in Shadow : On disappearing shadows of Birds and airplanes

     

Well, at least he understood enough to draw th…

Well, at least he understood enough to draw the image inverted

Ask Ethan: Could The Universe’s Missing …

Ask Ethan: Could The Universe’s Missing Antimatter Be Found Inside Black Holes?

“It is a mystery why we see matter without corresponding antimatter. Some remote and old super massive black holes evolved much faster than current theory is able to predict. Could the missing antimatter be hiding inside those primordial black holes? Does the total mass of super massive black holes come even close to the amount of missing anti matter?”

When we look out at the Universe today, we see that everything is made of matter and not antimatter. This is a puzzle, because the laws of physics appear to be symmetric between matter and antimatter: you can’t create or destroy either one without creating or destroying an equal amount of the other. Is it possible that we actually created equal amounts of both, and that the antimatter collapsed into black holes, which might be responsible for either supermassive black holes or primordial black holes as dark matter? While, on the other hand, the normal matter didn’t collapse, and became the stars, gas, galaxies, and more that we observe today?

It’s a fascinating alternative to the standard picture that our Universe is fundamentally asymmetric, but does it hold up? Find out on this week’s Ask Ethan!

humanoidhistory: Planet Jupiter, observed by N…

humanoidhistory:

Planet Jupiter, observed by NASA’s Juno probe on July 10, 2017. (As of this posting, Tumblr has marked this image as “sensitive” for some reason. I’m trying to see this like I’m an algorithm looking for something offensive. Does it look like a body part?)

(NASA)

The 19 Small Ways That NASA Will Try To Save T…

The 19 Small Ways That NASA Will Try To Save The Earth

“The key to adapting to a changing world, not just as individuals but as the human race, requires us to use the best tools and information at our disposal. That means paying attention to what the Earth is doing, both naturally and artificially, and using the best data available to drive our policy decisions. These 19 future missions represent the short-and-medium-term roadmap for NASA Earth Science, and every one of these missions is currently slated to go forward, as long as there aren’t unexpected cuts in the future. This Earth Day, don’t just celebrate our planet only to forget about it; keep in mind what we’re doing to learn about our world and why it’s valuable. This planet is the only Earth we’ve got, and it’s up to us to be good stewards of this world. Without quality scientific information on which to base good decisions, from a global perspective, we’d be nothing more than animals.”

When people think of NASA, they think of spaceflight, of technology, and of science. But most of the science they think of is astrophysics or planetary science, not Earth Science. Well, that’s foolish; Earth Science is one of the Science Mission Directorate’s four major realms of study, as we can learn things about our world from the air and from space that we cannot hope to learn from surface investigations alone. Over the coming months and years, NASA has 19 new missions slated to help better investigate and understand the Earth, including our weather, climate, pollution, CO2, temperature, and more. If you care about accurate information, you’ll start to understand why all of these missions are indispensable to a scientifically-minded society.

Come learn about the 19 small ways, from missions small to large, that NASA’s Earth Science directorate will try and help save the Earth.

Why is most of advanced physics just math ?

image

One of my professors was asked the same question and let me paraphrase his response:

You give up on intuition when it gives up on you.

One of the many reasons why most of physics is deeply mathematical is because our intuition alone is unable to explain all the results that we observe in nature and when that happens, we rely on mathematical theories to shed light on the nature of reality

LIGO Misses 100,000 Black Hole Mergers A Year …

LIGO Misses 100,000 Black Hole Mergers A Year

“The era of gravitational wave astronomy is now upon us. Owing to the incredible capabilities of ground-based detectors like LIGO and Virgo, we have now detected six robust events over the past 2+ years, from black holes to merging neutron stars. But huge questions surrounding the black holes in the Universe, such as how many there are, what their masses are early on compared to today, and what percent of the Universe is made of black holes, still remain to be answered. The direct efforts have gotten us a very long way, but the indirect signals matter, too, and can potentially teach us even more if we’re willing to make inferences that follow the physics and math. LIGO may be missing upwards of 100,000 black hole-black hole mergers a year. But with this new proposed technique, we might finally learn what else is out there, with the potential to apply this to neutron stars, non-merging black holes, and even the leftover ripples from our cosmic birth. It’s an incredible time to be alive.”

When you look up at the stars in the night sky, you think you’re seeing just countless numbers of them. It’s beautiful what’s out there, as you look up and take it all in. Break out the binoculars, and things get even more spectacular. Yet even with that assist, you’re missing nearly a million stars for every one you can see. That’s the same situation with black hole and neutron star mergers, where LIGO and Virgo have seen a total of six, but have missed nearly a million over the multiple years they’ve been running. Directly, there’s no way to see them with our current equipment. But from an aggregate computational perspective, we might be able to extract the true signal and know, at least statistically, how many black hole mergers are occurring in our Universe overall.

LIGO is missing over 100,000 black hole mergers a year, but thanks to a new technique, we might actually, for the first time, measure and learn what it is that’s out there. Here’s how.

Using Complex numbers in Classical Mechanics

image
image

** The reason why this is awesome is because one does need to worry about the unit vectors in the r and theta directions, which makes the algebra so much more simpler

NASA Kepler’s Scientists Are Doing What …

NASA Kepler’s Scientists Are Doing What Seems Impossible: Turning Pixels Into Planets

“It isn’t the image itself that gives you this information, but rather how the light from image changes over time, both relative to all the other stars and relative to itself. The other stars out there in our galaxy have sunspots, planets, and rich solar systems all their own. As Kepler heads towards its final retirement and prepares to be replaced by TESS, take a moment to reflect on just how it’s revolutionized our view of the Universe. Never before has such a small amount of information taught us so much.”

When you think about exoplanets, or planets around stars other than the Sun, you probably visualize them like we do our own Solar System. Yet direct images of these worlds are exceedingly rare, with less than 1% of the detected exoplanets having any sort of visual confirmation. The way most planets have been found has been from the Kepler spacecraft, which gives you the very, very unimpressive image of the star you see featured at the top. Yet just by watching that star, the light coming from it, and the rest of the field-of-view over time, we can infer the existence of sunspots, flares, and periodic “dips” in brightness that correspond to the presence of a planet. In fact, we can figure out the radius, orbital period, and sometimes even the mass of the planet, too, all from this single point of light.

How do we do it? There’s an incredible science in turning pixels into planets, and that’s what made NASA’s Kepler mission so successful!

The Most Important Equation In The Universe &…

The Most Important Equation In The Universe

“The first Friedmann equation describes how, based on what is in the universe, its expansion rate will change over time. If you want to know where the Universe came from and where it’s headed, all you need to measure is how it is expanding today and what is in it. This equation allows you to predict the rest!”

In 1915, Einstein put forth General Relativity as a new theory of gravity. It reproduced all of Newton’s earlier successes, solved the problem that Newton couldn’t of Mercury’s orbit, and made a new prediction of bent starlight by large masses, verified during the 1919 solar eclipse. Despite the fact that it included a cosmological constant to keep the Universe static, that didn’t deter Soviet physicist Alexander Friedmann from solving Einstein’s equations for a Universe that was filled with matter and energy, all the way back in 1922. The two generic equations he found, known as the Friedmann equations, immediately related measurable quantities like the amount of matter in the Universe to the expansion or contraction rate, which just years later became validated by Hubble’s observations. But the young Friedmann never lived to see it; he died of typhoid fever contracted when he was returning from his honeymoon in 1925.

Nearly 100 years later, it still stands as the equation that determines the history and fate of the Universe. Come see why I call it the most important equation in the Universe!