Sonic booms

An observation from a reader sent me on a search for a good photograph of a sonic boom, and inevitably, I ended up chasing facts and cool tidbits down a few rabbit holes.

First cool tidbit: Sonic booms are created by shock waves, and those shock waves were first photographed in 1888 by Ernst Mach, who was studying the pressure waves produced by bullets traveling at supersonic speeds.

Mach bullet

What he discovered was that there are two pressure waves, one at the front of the projectile and one at the back. Stanford University has a great write-up about these famous photos and the technique used to produce them.

(Mach’s research produced the equation that immortalized his name: a Mach number is the ratio of the speed of a traveling object to the speed of sound in the medium through which that object is traveling.)

The bullets create those shock waves by shoving molecules aside with the force of their passage, much the way a ship creates a wake as it moves through water. The bigger and heavier a traveling object is, the bigger the shock waves it produces.

Which brings us to the shock waves we all know about: sonic booms.

NASA has a spiffy little fact sheet on sonic booms, offering this succinct explanation:

The shock wave forms a “cone” of pressurized or built-up air molecules, which move outward and rearward in all directions and extend all the way to the ground. As this cone spreads across the landscape along the flight path, it creates a continuous sonic boom along the full width of the cone’s base. The sharp release of pressure, after the buildup by the shock wave, is heard as the sonic boom.

The change in air pressure associated with a sonic boom is only a few pounds per square foot — about the same pressure change experienced riding an elevator down two or three floors. It is the rate of change, the sudden changing of the pressure, which makes the sonic boom audible.

The closer the source of the cone, the louder the boom. As the cone travels farther down through the air, it widens and weakens, so the boom created by a high-flying supersonic aircraft won’t be perceived as loud on the ground, while a boom from the same aircraft screaming by 500 feet overhead will knock your socks off.

(Seriously, check out that fact sheet. Especially the part about overpressure.)

Back to those bullet photos up above. Remember the two pressure waves? Those form on jets, space shuttles, and rockets, too. So they all create double sonic booms, but we often hear the two booms as a single sound because they’re so close together. For instance, a supersonic fighter jet 50 feet long will generate nose and tail shock waves that are about one-tenth of a second apart. We can’t hear that difference. But the Space Shuttles, famous for their double booms, were 122 feet long. That meant their nose and tail shock waves were about a half-second apart, and that is distinguishable to our ears.

Though the Space Shuttles are retired, sonic booms have returned to Florida’s Space Coast with the advent of SpaceX and their rocket launches, with one spectacular difference: the SpaceX rockets produce triple booms as they land. That’s because of their shape. As explained in Space Flight Insider:

“[The] first boom is from the aft end (engines),” said John Taylor, SpaceX’s Communications Director. “[The] second boom is from the landing legs at the widest point going up the side of the rocket. [The] third boom is from the fins near the forward end.”

Want to hear that? Check out this video. I’ve cued it to just before the booms, but you really should watch the whole thing, with headphones on, because it is super cool.


Now for a bit of urban mythbusting. You’ve probably seen this photograph, which was taken by Ensign John Gay of the US Navy in July 1999:

Navy not boom

This is not a sonic boom, though practically every site/blog/article that has ever featured it claimed it was. It’s actually a phenomenon called flow-induced vaporization. Atlas Obscura has a wonderful article on when and how this photo was taken, how shocked Ensign Gay was to return from his tour at sea to learn that the photo had become world famous, and what he really photographed.

I did, however, find a great photo of an actual sonic boom produced by a jet. It will look very familiar to you:

Supersonic jumbo

It’s been more than a century since Ernst Mach took those images of the bullets, but the technique used for this jet photo is exactly the same. The New York Times has a write-up on how it was produced. For most people, it wouldn’t have the visual punch of the wrongly-labeled photo by Ensign Gay. But having been down the various rabbit holes, we know what this image is actually showing, and that what Mach did in 1888 with a bullet is the exact same thing a NASA scientist did in 2015 with a supersonic jet.

And that is cool.

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Posted in science | 6 Comments

Brexit view from the continent

Yesterday, the papers were full of news of Teresa May’s fruitless attempt to break the negotiating stance of the EU regarding Brexit. Or at least, the UK papers were full of that news. Continental papers, not so much. It was a fascinating real-time example of the wildly divergent view that different people, cultures, and governments can have of the same event.

When the Brexit vote hit in June 2016, it was front page news everywhere in Europe. It continued to be front page news as the ramifications were explored and as the UK invoked Article 50, which activated an unstoppable two-year clock.

With the clock now counting down the final months, the UK continues to be consumed with Brexit, both in its government and its news coverage. Over here on the continent, however, interest in Brexit has declined on a daily basis. The EU has plenty of things to be concerned about: the migration issue, Italy’s financial stability, the alarming assault on democratic norms in Hungary and Poland. And of course, every country has its own internal concerns. Brexit is considered regrettable and costly, but it is not by any means the top news, and hasn’t been for a long time.

Meanwhile, UK Prime Minister Theresa May has fought a running battle in her own cabinet between hard Brexiteers who crave no deal at all (also called “crashing out”) and the moderates who are horrified at the towering economic, environmental, and social costs of that. Her solution was a proposal called Chequers, which made absolutely no one happy — not the hardliners, not the moderates, and not the EU negotiator, whose stance has been unchanged since this whole thing started. So the process has been something like this:

EU: We will not accept a deal that alters A, B, C, or D, any of which would undermine the integrity of our union. We will negotiate on the other items.

UK: We want to change A and B.

EU: No. A, B, C, and D are non-negotiable.

UK: What if we only change A and B a little bit?

EU: A, B, C, and D are non-negotiable.

UK: Okay, here’s this deal called Chequers. It changes A and B, but you really need to give us some political cover here.

EU: A, B, C, and D are non-negotiable.

That last bit occurred Thursday, when Theresa May went to an EU summit in Salzburg to present her Chequers plan. The EU negotiator had already dismissed the plan as unworkable months earlier, practically the day after it came out. Everyone has known the EU would not accept it.

The EU did not accept it.

The following day, the UK news was full of the “ambush” at Salzburg, saying Theresa May was “blindsided,” “humiliated,” and other choice descriptive phrases. It’s as if no one could have possibly predicted such an outcome. Except that over here on the continent, everyone predicted that outcome. How can that be an “ambush”?

Here, then, is an illustration of different views of the same event. First, a pro-Brexit British tabloid called The Sun:

Sun paper

The tommy guns are a nice touch, as is the subheader: “We can’t wait to shake ourselves free of the two-bit mobsters who run the European Union.”

The Times was more sober, but still apparently astonished:

Times Brexit

The Guardian has a roundup of all the UK front pages on Friday. They’re all along the same theme.

Meanwhile, here is the front page of one of Portugal’s largest newspapers:

Publico Brexit

The prime photo real estate goes to Portugal’s president, who was a professor of law before taking office. He was teaching one final class.

Over on the right is the news about Salzburg. The headline is: “EU says to May that her plan for Brexit is unacceptable.” And right below that is the headline, “Should it be legal? Debate joins ex-prostitutes in Lisbon.”

As you can see, it wasn’t big news.

Posted in Europe, politics | 2 Comments

“Portugal is not the USA”

I’m guessing this was not trumpeted all over the US news, but the President of Portugal, Marcelo Rebelo de Sousa, met with Trump at the White House last week.

The meeting started off with a handshake. It’s clear from this video that Marcelo had undergone diplomatic training in how to deal with Trump’s infamous “grab and pull” handshake-disguised-as-dick-waving.

It seems the training went well.

This isn’t what made the Portuguese headlines, however. The big news here was Trump’s attempt at a joke and Marcelo’s withering reply.

It started when Marcelo commented that if Trump was going to be in Russia to meet Putin, he should attend the World Cup, where the greatest footballer in the world was playing.

Trump joked, “Could Cristiano run against you [for president]?”

“He wouldn’t win,” Marcelo replied instantly. “Portugal is not the US; it’s a little different.”

The Portuguese loved this. Because it’s true. Cristiano Ronaldo might be the most famous person in Portugal (and surely one of the wealthiest), but the Portuguese are not swayed by fame or wealth in their elections.

Not to mention that these days, most citizens of Europe are looking across the pond in utter horror. Having our president affirm that Portugal isn’t the US was a point of civic pride.

The exchange made headlines the next day:

Publico Marcelo

Here’s another Marcelo story that I’m sure no one outside Portugal has heard: on his first day as President, he walked to work. He happened to live near the Palácio Belém (the Portuguese version of the White House), so why not?

No, Portugal is not the US. It’s a little different.

Posted in politics, Portugal, USA | 13 Comments

The giant salmon was my favorite

This video is a 100% accurate depiction of my home state. More or less.

Posted in Oregon, video | 13 Comments

The right-wing megacorp controlling your local news

Once upon a time, your local news stations were a reliable bastion of independent journalism. Chance are good that isn’t the case now.

If your local station is owned by Sinclair Broadcast Group, then it is required to run certain news and opinion pieces produced by Sinclair, not by any local journalist. It is required to air a daily “Terrorism Alert Desk” segment — also produced by Sinclair — regardless of any actual alert or danger. It is required to read transcripts written by Sinclair. Those programs and transcripts serve a political agenda.

This brilliant video demonstrating the power of Sinclair’s propaganda machine is just 1:38 minutes long and might freeze your blood.

If the word “Orwellian” just popped into your head, you are not alone.

An excellent Guardian article delves into Sinclair and its newfound power under the Trump administration, which is busily relaxing regulations that had previously limited Sinclair’s reach. Michael Copps, a former FCC chairman appointed by George W Bush, calls Sinclair “probably the most dangerous company most people have never heard of.”

John Oliver ran an informative and darkly humorous segment on Sinclair as well — if you don’t want to dig into the Guardian article, watch it below.

Wikipedia has a list of stations owned by Sinclair Broadcast Group. I checked it to see which Oregon stations are under its thumb, and found that Sinclair has a strong hold on Oregon broadcasting:

  • KVAL and KMTR in Eugene, the CBS and NBC affiliates (which also air in Coos Bay and Roseburg on four satellite stations).
  • KTVL in Medford.
  • KATU and KUNP in Portland, the ABC and Univision affiliates.

Between those five stations and their four satellites, Sinclair can reach the majority of Oregon households. The only major city it doesn’t cover is Salem.

Frightening. And very likely to get worse.

Posted in politics, USA | 1 Comment

Why our oven clock is slow

Clock

File this one under “I’ll be danged, I didn’t know that.”

Over the last couple of months, the clocks on our oven and microwave have been…off. First a minute, then a couple, then five, then six. I hadn’t consciously thought about why, but simply did what we humans are so good at and adjusted, because I was too lazy to reset the clock. “Hm, the oven clock says it’s 12:45, so that means it’s 12:51.”

It turns out that this was happening all over Europe. And the reason is…Kosovo.

There are two important bits to understanding this bizarre situation:

1. Cheap electronic clocks don’t tell time via a quartz crystal or an internet connection, which are relatively expensive methods. Instead, they use the cheaper method of synchronizing to the frequency of the mains electricity supply, which should be precisely 50 Hz.

2. Europe has the world’s largest synchronous electricity grid. Regional power companies coordinate with each other to keep electricity moving smoothly across the borders of 25 countries — and to maintain the frequency at 50 Hz.

But from mid-January to March 6, a tiny bit more power was being consumed than produced, leading to an average Europe-wide grid frequency of 49.996 Hz. So for around two months, all of those cheap clocks that tell time by frequency synchronization were convinced that time was moving a tiny bit slower.

Why is it Kosovo’s fault?

Having only declared independence from Serbia ten years ago, Kosovo is not a unified nation (or even fully recognized). Many in the north still consider themselves Serbian and refuse to pay Kosovo for their electricity, even though that’s where it’s generated. Thus Kosovo is unable to bill for some of its output, which of course affects production. In January, Kosovo failed to balance this out, and for two months continued to produce less power than was used. This net loss affected the entire European grid, reducing the grid-wide frequency by 0.004 Hz.

And all of our cheap clocks ran slow.

The Powers That Be (literally, ha) tell us that Kosovo has rebalanced and that the grid is recovering, but getting back to 50 Hz might take a bit of time. And since the political situation that caused the issue is unsolved, there’s no telling when/if it might happen again.

In the meantime, my expensive and extremely accurate laptop clock tells me it’s currently 13:33. The oven says it’s 13:27. I guess it’s time to finally fix it.

Posted in Europe, tech | 2 Comments

Long live the humanities

Omaha Beach

In an essay for the Chronicle of Higher Education, English professor Nina Handler laments the extinction of her species:

Charles Smithson, a character in John Fowles’s 1969 novel, The French Lieutenant’s Woman, is a wealthy, idle gentleman who faces the challenge of realizing that he, as a type, is becoming extinct. The novel is set in 1867, and Charles, a devotee of Darwin, considers the recently published On the Origin of Species to be his bible. His social class will cease to exist within a generation, and Charles has both the wisdom to see that he must adapt and the self-awareness to know that he is incapable of it. He is being swept away by evolutionary change but is helpless to change his fate.

I am a college English instructor. This is a bad time for my species — and a bad time for the study of English. In academe, we are witnessing an extinction of fields of study once thought essential. I teach at a private university that has just canceled majors in English, religious studies, philosophy, and music. The English major is becoming the useless gentleman, the Charles Smithson, of the modern university.

It’s a disheartening essay, particularly when she points out that as education becomes merely a hoop to jump through in order to find work, the values assigned to that education relate solely to its vocational utility.

I fully understand that, because when I declared for English as my major — way back in the mid-80s — everyone had the same question: “Oh, so you’re going to be an English teacher?” As if getting a bachelor’s degree in the study of literature could not possibly qualify me for anything other than turning around to teach others to study the same thing.

“No,” was my answer.

“Then what?”

“I don’t know.” At the age of 19, how would I know what I planned to do with my life? I thought the point of a university education was to equip me with the tools I could use to figure that out — and for the rest of my days thereafter.

Thirty years ago, most people could not comprehend choosing a university degree that had no immediate and obvious path to employment. I don’t think what Nina Handler is experiencing is new. But I do think it has gotten much worse.

What I know for certain is that my English major taught me critical thinking skills. It taught me philosophy and the universality of human experience. It taught me about worlds, times, and cultures I could never live in, but could visit in my mind. It led me to the realization that I was not just an American, but a citizen of the world living on a tiny point in the vast tide of human history.

As I watch the alarming rise of racism, nationalism, and other-blaming hatred in my home nation, in post-Brexit Britain, and in too many other places, I don’t think it’s the humanities that are in danger. I think it’s what the humanities create: educated citizens of the world who care about more than just themselves. People who see the improvement of others’ lives as a benefit to all, not a threat to their pocketbook or sense of identity. People who respond to differences with curiosity, not fear.

But as a humanities major, I know that all of this has happened before. I know the horrors it can lead to. I also know that humans have approached this brink — and gone over it — time and time again. Yet even in the worst of times, there are brilliant lights of our species’ greatest potential. There are creators of wondrous music, art, and literature. There are scientific breakthroughs. There are people who risk themselves to help others they don’t even know, simply because it is the right thing to do.

If I could go back to my 19-year-old self, I would offer a different answer to that question of “What are you going to do with an English degree?”

I would say: I am going to live a rich, diverse life that takes me places I never expected. And I am going to hope.

Happy holidays to all those who celebrate in their diverse ways.

(I took the photo at top in Normandy, France. Les Breves was sculpted by Anilore Banon, and stands in the sands of Omaha Beach as an homage to the many who died there in order to liberate a captive land. The three sections represent three elements: the Wings of Hope, Rise Freedom, and the Wings of Fraternity. Created for a temporary installation, this luminous art has been so popular that it remains indefinitely, a blending of art and nature: humanities at their finest.)

Posted in culture, life | 12 Comments

MIND BLOWN: the lightning edition

Stop what you’re doing and watch this video. But watch it the right way: full screen, in a darkened room, and with a good sound system turned up.

This is 3:18 minutes of the best lightning footage I’ve ever seen, cut and edited into a jaw-dropping video with music that perfectly complements the drama. After watching it with me, my son said, “I never knew lightning moved that way.”

I said, “No one did until a few years ago. The technology didn’t exist to capture something that moved at the speed of light.”

For me, geek that I am, one of the coolest things about this video is that it exists. I remember when the first footage was made available from a scientific study of lightning that involved a concrete bunker (for sheltering the scientists), an electrical system designed to attract a lightning bolt, and what was then a state-of-the-art slow motion camera. The scientists shot unending amounts of film recording absolutely nothing when their system didn’t attract a bolt, but eventually managed to capture a few important seconds amongst all those hours and hours of footage. Their published article, with accompanying video, changed the body of thought on how lightning traveled.

That wasn’t very long ago — but technology has moved only a little slower than the speed of light.

Photographer Dustin Farrell spent the summer of 2017 chasing storms while toting a 4K camera rig that takes 1000 frames per second of raw, uncompressed footage. (For comparison: most movies are shot at 24 frames per second.) After driving 20,000 miles over a 30-day period, he had recorded 10 terabytes of data, which he then whittled down to 3:18 of spectacular video.

What enabled his success was not just the ultrafast frame rate of modern cameras, but also the recording technology in which a camera constantly records, writes to RAM, then overwrites, and overwrites again…until a button is pressed to save the RAM contents. This is the tech currently used in police body cameras. It’s why, when an officer activates a body cam, the recording actually starts 30 seconds earlier. It’s not that the camera is a time machine, it’s that it is saving the footage already recorded but not yet overwritten.

You can imagine how handy this is in taking video of lightning. Now, instead of “rolling film” for an hour-long storm and waiting for a bolt to happen, Farrell could simply press a button the moment he saw a bolt and voila, he caught it.

So…take a look at what he caught.

(Hat tip to Ally.)

Posted in science, weather | 6 Comments

A side note to Anita Hill’s story

Anita Hill

Many of us are remembering Anita Hill’s trailblazing courage these days, as the dams are breaking and so many women are telling their stories of sexual harassment and sexual assault.

What is rarely recalled now is that the 1991 Senate confirmation vote was a huge fight, with six Democratic senators switching their “yea” votes to “nay” over the weekend after the hearings. It wasn’t enough, and Clarence Thomas was confirmed by a vote of 52-48.

Only two Republicans voted against Thomas. One was James Jeffords from Vermont. The other was Bob Packwood from Oregon.

One year later, we Oregonians realized the great irony of Packwood rebelling against his party to prevent a sexual abuser from being seated on the Supreme Court. Ten women, most former lobbyists or Packwood staffers, came forward to accuse him of sexual harassment, abuse, and assault. The Washington Post had the story but held it until after the November election, in which Packwood defeated Democratic challenger Les AuCoin. (I remember that race well.)

For three years, my state was roiled by the ongoing investigation into Packwood. Eventually, a total of 19 women were willing to follow the example of courage that Anita Hill burned into our national consciousness.

Packwood’s diary became a topic of water-cooler conversation and considerable legal wrangling. Could it be subpoenaed, or was it covered by the Fifth Amendment? He eventually turned over 5,000 pages to the Senate Ethics Committee, but when it became obvious that those pages were edited, the committee demanded another 3,200 pages. Packwood refused.

And here is where Packwood made his fatal mistake. Angry at what he perceived as being singled out, he issued a veiled threat to the effect that many others in the Senate had done the exact same thing (which of course we know was true) — and demanded that his hearings be public.

That did not go over well. The Senate Ethics Committee recommended that Packwood be expelled from the Senate “for sexual and official misconduct,” a truly nuclear option that forced Packwood to resign.

In the special election to replace him, Oregon elected then-US Representative Ron Wyden, a Democrat. He has since become a powerful voice for affordable health care, human rights, and civil liberties, while voting against the war in Iraq and the reauthorization of the Patriot Act. He has done a great deal to raise awareness of, and attempt to limit, the vast American surveillance state currently spying on its citizens. In short, he has been everything I could hope for in a senator.

Meanwhile, Bob Packwood retired on a comfortable $90,000/year pension with full benefits. For years, I had a printout of one of his diary entries on my office wall, because it was so indicative of the entitled mindset that eventually brought him down. It was from November 8, 1993, and said:

“Well, I did wrong, and I know I did wrong, but I’ve been caught, so I’ll call it misjudgment.”

Posted in history | 3 Comments

Energy disruption

This is a long video at 40 minutes, but it is a fascinating and fast-moving talk on the massive disruptions caused by wind and solar in the electrical power markets, as well as the disruption caused by batteries, tech, and electric vehicles in the oil markets.

There is no way that the CEOs and investors of US coal companies don’t know these statistics. They know that solar and wind are now equal in cost-per-kilowatt-hour to coal, and in the latest bids, far cheaper — even without subsidies. They know their industry will soon be made obsolete due to market pressures.

The current US administration’s behavior in stopping any attempt to regulate the amount of toxic metals (such as arsenic and mercury) that coal plants are allowed to dump in public waterways, and rolling back the Clean Power Plan while declaring “the war on coal is over,” is not about bringing coal jobs back. Those jobs are never coming back, and many more jobs will soon be lost. What those behaviors are really about is enriching the billionaire CEOs and investors. They are cashing out while they can, and they do not give one flying fig about American workers or the environment (national or global). Neither does the administration.

Meanwhile, other nations are going all in on what they can clearly see are the technologies and power sources of the near future. The statistic about China cancelling 104 planned coal power plants ($80 billion in investment) in January of this year is mind boggling. Forty of those plants had already broken ground. “At least $20 billion was just thrown away,” the presenter says, and why would China do that? The Chinese are nothing if not ruthlessly pragmatic.

The US under Trump is looking backward, filling the pockets of the mega-rich while hobbling the nation as other world players take the lead in technology and production. Our loss is the world’s gain, though — and watching this video is one of the most uplifting moments I’ve had this year. It gives me hope.

(Hat tip to TYWKIWDBI.)

Posted in good news, politics, tech | Leave a comment