electromagnetism

sciencealert.com
NASA has trialled an engine that would take us to Mars in 10 weeks
And may have inadvertently created a warp drive in the process.
By Fiona MacDonald

NASA scientists have reported that they’ve successfully tested an engine called the electromagnetic propulsion drive, or the EM Drive, in a vacuum that replicates space. The EM Drive experimental system could take humans to Mars in just 70 days without the need for rocket fuel, and it’s no exaggeration to say that this could change everything.

But before we get too excited (who are we kidding, we’re already freaking out), it’s important to note that these results haven’t been replicated or verified by peer review, so there’s a chance there’s been some kind of error. But so far, despite a thorough attempt to poke holes in the results, the engine seems to hold up.

Continue Reading.

The integral form of Maxwell’s equations etched in concrete on the side of the Warsaw University Library. (which make this library utterly badass).

Together these equations showed that electricity, magnetism and light are all 3 aspects of the same single phenomenon known as electromagnetism. Using these equations the existence of electromagnetic waves was predicted long before the discovery of them, and even more amazingly light itself was shown to be an electromagnetic wave traveling through space.

Radio technology, wireless communication, the understanding of what light is, all began with those equations. 

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Magnetic Field and Electric Field: Two Sides Of A same Coin

Probably, I won’t be able to give a satisfying answer to this question, but it’s the risk we take when we ask the Why of a physical phenomenon –instead of how physics can describe a natural phenomenon– and we don’t want a metaphysical answer. I don’t know how to give a direct answer, so I’m going to make a brief review of the milestones that have characterized this branch of physics (electromagnetism), with the hope  to remove some doubt.

Until the early decades of the 1800’s, experiments conducted to investigate electrical phenomena were completely separate from those focused on magnetic phenomena. Then, in 1820, Hans Christian Oersted –a Danish physicist and chemist– saw by chance that the needle of a compass is deflected from magnetic north if placed near a wire in which an electric current is flowing. Repeating the experience several times in a rigorous way, he demonstrated that an electric current generates a magnetic field, establishing for the first time a relationship between magnetism and electricity.

Keep reading

Ok so I thought it was necessary to make this response a post of its own… continued from here.

Edit: I added some info from commenters clearing up some things and cleaned up the format a bit.

cosmicmachinery:

wildcat2030:

Here’s What Wi-Fi Would Look Like If We Could See It

(Wildcat2030, I love you but I just- I just gotta debunk the crap out of this real quick)…

Wi-fi. It’s all around us, quietly and invisibly powering our access to the world’s information. But few of us have a sense of what wi-fi actually is, let alone what it would look like if we could see it. Artist Nickolay Lamm, a blogger for MyDeals.com, decided to shed some light on the subject. He created visualizations that imagine the size, shape, and color of wi-fi signals were they visible to the human eye. “I feel that by showing what wi-fi would look like if we could see it, we’d appreciate the technology that we use everyday,“ Lamm told me in an email. “A lot of us use technology without appreciating the complexity behind making it work.” To estimate what this would look like, Lamm worked with M. Browning Vogel, Ph.D., an astrobiologist and former employee at NASA Ames. Dr. Vogel described the science behind wireless technology, and Lamm used the information to create the visualizations. (via Here’s What Wi-Fi Would Look Like If We Could See It | Motherboard) (Nah, don’t even click this link. What are you thinking?)

Here’s all the reasons why this article is entirely wrong. It’s really really wrong:

The wifi range is just another set of wavelengths. In other words, it would be a continuation of what we can already see in the electromagnetic spectrum. Since color varies with wavelength, it is only reasonable to assume that wifi/radio/any electromagnetic source would look like any other light source with a different (new) color of light.

And, since at wifi wavelengths the waves are not absorbed by walls and stuff, we’d be able to see these electromagnetic sources through walls. It would be like the walls were clear to that particular color of light, just like how certain substances, like glass, do not absorb wavelengths in the visual spectrum.

The minimum threshold for the perception of light is very very low, on the order of 10^-15 watts. My own router broadcasts at 60mw. Laser pointers are eye-safe around 5mw, and lasers past 30mw are used for cool lighting effects for stages and stuff, so routers would also be powerful enough for us to see.

Sources: Engineering physics courses, electronics courses (covering optoelectronic devices like photodiodes and laser diodes) and a couple minutes on Google to tie it all together. Let me know if I’ve gotten anything very wrong.

And don’t forget that this article offers no reasoning beyond “it’s from a NASA astrobiologist" for its validity.

(^Yes^ comsmicmachinery, I don’t even know you but I love you!)
This was bugging me too…
I know the artist deserves some artistic leeway but these illustrations are so wrong it hurts me.

And I’m pretty sure most Wifi signals are the same wavelength, so if we could see it, it would just be the same color, whatever that may be to our brains.
– But the artist had to use some color that we could already see. Like me trying to point to the 4th dimension (impossible btw) but in this case trying to show a new color. – 

Edit – Clarification from enki2:

Wifi doesn’t actually stick to a single wavelength; one of the big and interesting advances in wifi is that it combines separate signals on completely different frequency ranges and switches them up in a complex way as a mechanism for collision avoidance.

(So I it does use different wavelengths. I’ll assume that the frequency modulation would result in shifting colors from white to any other combination but this would also happen very quickly)

Maybe a little variances but I’m not an expert on this stuff (<– this is important for the rest of the article). Since we are talking about perception of color, check out this epic video by Vsauce. Ok, back to the wifi thing.

The electromagnetic spectrum for reference…

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(yea, we are basically blind)

Also, the waves wouldn’t just sit on the ground like some sort of fog like in the pic below. Wifi is just like any other electromagnetic signal and will radiate all around.

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And I can hardly get a signal in my own damn house sometimes, so I really doubt you would be able to see wifi signals far away from you. Unless maybe you were near some cell phone tower, which would be blindingly bright (in that new color or a combination of new colors) if you stood next to it. And as the person above explained, your router would glow brightly as well, along with anything that emitted that wavelength and made it to your eye.

So walking into a mall and shopping would be difficult (or just approaching one and trying to find the entrance since the signals go through walls) considering they are usually filled with these signals and shopping with a flood-light in front of your face is kind of hard (not speaking from experience).

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The artist stresses that you would be able to see the crests of the waves themselves. No, these are not something physical just floating around in space as if it was a magical ribbon flying around. No, other light waves are not bouncing off these waves illuminating the crests and troughs allowing us to see the different parts of the waves.The only reason you can see something is because a protein in your eyeball just got blasted with a photon and eventually caused a neuron in your brain to fire. The same thing would go on here, just with a different wavelength.

That pond of water right there wouldn’t be reflecting that wifi-light either. If we were seeing only those wavelengths, the pond would be black because it absorbs them (see spectra below), otherwise it would just be the blue color we normally see. It might be darkened a bit depending on how our brains would interpret seeing both the reflecting blue-light and the absence of the wifi-light.

And according to this

So what kind of energies are we looking at in WiFi signals? WiFi operates in the 2.4 GHz frequency range, the same as a microwave oven. The wavelength of that light is about 12.5 centimeters, which is about 125 million nanometers.

…wifi uses the same wavelength as a microwave oven, and I know cell phones use the microwave part of the spectrum as well (or about the same wavelengths, just depends on the phone I guess – but why would you evolve to only see ONE particular wavelength anyway, amiright?). So you would also be able to see cell phone signals too.

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I guess the sky would just be filled with this new color, unless maybe it was humid or raining, because water absorbs those wavelengths (see the spectra above). Now you know why you get bad reception in rain.

Tangent:
That’s how your microwave works by the way. Also, water absorbs blue the least, that’s why it looks blue to us – It would look crazy to bees (normal to them anyway) since they can see Ultraviolet to ~1mm wavelengths (radar).

Also your microwave, when turned on, would not glow in this new color. You ever wonder why that mesh is there on the door? That keeps the microwaves in!

Anyway, off track there for a second. Since we are just talking about the sky, the night sky would be completely different if you could see these waves.

The reason the night sky isn’t filled completely with stars is that the further away something is, the faster it is moving away from you and thus the light it emits gets red-shifted (here is an excellent post on that).

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Oh look! Microwaves are basically a really-really red-shifted wavelength.

See the Cosmic Microwave Background Radiation oh and MASERS in space are a thing too (like LASERS but with Microwaves).

And it seems radio waves and microwaves are able to make it through our atmosphere (if only a small amount), so you would be able to see more objects in the sky. That is, assuming you could differentiate from all of the other man-made signals flying around.

Because of this red-shifting, right now when you look up at night, you are only seeing stars in our own galaxy the Milky Way and a few other things like the Andromeda galaxy but most of it is from our galaxy. – (fun fact: we will crash into Andromeda eventually) – So being able to see this red-shifted wavelength allows you to see more objects that are further away AND those objects in a completely different light… literally.

One of the many reasons we have different telescopes that use different wavelengths is so we can see different things. – Here is a cool tool showing the different telescopes we have and the light they see in.– As soon as we starting looking at the Milky Way core in infrared for example, we can see through all of the dust in the way, allowing us to make this gorgeous 9gigapixel image of our galaxy.

Now THAT is fucking awesome! So whoever the artist was on this, take some notes and try again. Courtesy of: SCIENCE!


It may look like a giant ball oozing with earthworms, but it’s actually a simulation of Jupiter’s massive and complex magnetosphere — a magnetic field that extends more than four million miles from its surface.

The Earth generates a magnetic field by the convection of molten nickel-iron alloys in its outer core. Jupiter’s outer core is also thought to be responsible for its enormous magnetic field, though it is liquid hydrogen crushed by intense pressure into a metallic form that generates the magnetism rather than iron compounds. In addition, the gas giant’s surface is buffeted by powerful winds and huge storms, like the famous Great Red Spot. Scientists believe that these surface winds interact with the metallic liquid hydrogen below to stimulate some of the secondary properties of the magnetic field. 

Magnetic fields of planets compared:

(Sources 1, 2, 3

For teaching: astrophysics

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New mugs from one of our favorite nerdy design companies: Cognitive Surplus

For those of you awake to learn or at least study during your morning coffee, these are for you. :) 

Star chart mug

Lunar phases mug

Electromagnetism mug

And many more across the sciences!

Check out all our Cognitive Surplus posts here

- Summer

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Nikola Tesla

Nikola Tesla (10 July 1856 – 7 January 1943) was a Serbian-American inventor, mechanical engineer, electrical engineer, and futurist. He was an important contributor to the use of commercial electricity, and is best known for developing the modern alternating current (AC) electrical supply system. His many revolutionary developments in the field of electromagnetism in the late 19th and early 20th centuries were based on the theories of electromagnetic technology discovered by Michael Faraday. Tesla’s patents and theoretical work also formed the basis of wireless communication and the radio. 

Tesla was renowned for his achievements and showmanship, eventually earning him a reputation in popular culture as an archetypal “mad scientist.” His patents earned him a considerable amount of money, much of which was used to finance his own projects with varying degrees of success. He lived most of his life in a series of New York hotels, through his retirement. He died on 7 January 1943. His work fell into relative obscurity after his death, but in 1960 the General Conference on Weights and Measures named the SI unit of magnetic flux density the tesla in his honor. Tesla has experienced a resurgence in interest in popular culture since the 1990s. Read More | Edit

“Aristotle taught that there was an immovable ‘entelechy’ in the universe that moves everything and the thought was its main attribute. I am also convinced that the whole universe is unified in both material and spiritual sense. Out there in the universe there is a nucleus that gives us all the power, all the inspiration; it draws us to itself eternally, I feel its mightiness and values it transmits throughout the universe; thus keeping it in harmony. I have not breached the secret of that core, still I am aware of its existence, and when wanting to give it any material attribute I imagine LIGHT, and when trying to conceive it spiritually I imagine BEAUTY and COMPASSION. The one who carries that belief inside feels strong, finds joy in his work, for he experiences himself as a single tone in the universal harmony.”Nikola Tesla (From the text “Nikola Tesla, Our First Great Ambassador in the USA” of Vladislav Savic, published in ‘Tesla Magazine’ 1951.)

Hubble Sees a Flickering Light Display on Saturn

Astronomers using the NASA/ESA Hubble Space Telescope have captured new images of the dancing auroral lights at Saturn’s north pole.

Taken from Hubble’s perspective in orbit around the Earth, these images provide a detailed look at Saturn’s stormy aurorae — revealing previously unseen dynamics in the choreography of the auroral glow.

The cause of the changing patterns in Saturn’s aurorae is an ongoing mystery in planetary science. These ultraviolet images, taken by Hubble’s super-sensitive Advanced Camera for Surveys, add new insight by capturing moments when Saturn’s magnetic field is affected by bursts of particles streaming out from the Sun.

Saturn has a long, comet-like magnetic tail known as a magnetotail — as do Mercury, Jupiter, Uranus, Neptune and Earth [1]. This magnetotail is present around planets that have a magnetic field, caused by a rotating core of magnetic elements. It appears that when bursts of particles from the Sun hit Saturn, the planet’s magnetotail collapses and later reconfigures itself, an event that is reflected in the dynamics of its aurorae.

Some of the bursts of light seen shooting around Saturn’s polar regions travelled at over three times faster than the speed of the gas giant’s rotation!

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Simulating the void of space with ESA’s Maxwell test chamber

These 9 m-high spike-lined walls enclose the European Space Agency’s Maxwell test chamber, which isolates satellites from all external influences to assess their electromagnetic compatibility.

Once its main door is sealed, the metal walls of the chamber form a ‘Faraday Cage’, screening out external electromagnetic signals. The echo-free foam pyramids covering its interior absorb internal signals – as well as sound – to prevent any reflection, mimicking the infinite void of space.

The satellite’s systems are then switched on to detect any harmful interference as its various elements operate together. 

Maxwell is part of the test centre in ESA’s technical heart in Noordwijk, the Netherlands – Europe’s largest satellite testing facility.

image credit:  ESA, Guus Schoonewille, Anneke Le Floc'h

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Why doesn’t our Universe have magnetic monopoles?

“So he built this device and waited. The device wasn’t perfect, and occasionally one of the loops would send a signal, and on even rarer occasions, two loops would send a signal at once. But you’d need eight (and exactly eight) for it to be a magnetic monopole. The apparatus never detected three or more. This experiment ran for some months with no success, and was eventually relegated to being checked up on only a few times a day. In February of 1982, he didn’t come in on Valentine’s Day. When he came back to the office on the 15th, he surprisingly found that the computer and the device had recorded exactly eight magnetons on February 14th, 1982.”

The laws of electromagnetism could have been incredibly different. Our Universe has two types of electric charge (positive and negative) and could have had two types of magnetic pole (north and south), but only the electric charges exist in our Universe. At a fundamental level, between electricity and magnetism, nature is not symmetric. But it could have been! Magnetic charges could move and make currents; a changing electric field could induce them; north and south poles could be separated an infinite distance. Magnetic charge could even have been a fundamental property of black holes. In 1982, Blas Cabrera announced the first detection of a long-sought-after magnetic monopole event, and the physics world went crazy. But nearly 35 years later, a second monopole has never been found. Despite our dreams, it looks like nature isn’t symmetric after all.

Lenz’s law states that the induced electromotive force in any circuit is always in a direction to oppose the effect that produced it. That’s why connecting a coil of wire to a battery doesn’t make much happen, while disconnecting them results in a flash.
That’s a bit oversimplifying it as the law actually covers magnetic fields, electromotive force, magnetic flux etc, so if you’re interested, it’s well explained here and here :) Oh, and don’t try this at home.