Let’s use our car again, but this time we’ll get real numbers from the accelerometer in our smartphone. Say we start at a red light and then accelerate at 2 m/s² (meters per second squared) for five seconds. From the equation above, Δv₁ would be 2 x 5 = 10 m/s, so that’s our velocity. Now, after cruising for a while, we accelerate again at 1 m/s² for five more seconds. Δv₂ is then 1 x 5 = 5 m/s. Adding these two changes, our velocity is now 15 m/s. And so on.

The only problem is that inertial measurement isn’t as accurate as the Doppler method over long periods, because small errors will keep accumulating. That means you need to recalibrate your system periodically using some other method.

Optical Navigation

On Earth, people have long navigated by the stars. In the northern hemisphere, just find Polaris. It’s called the North Star because Earth’s axis of rotation points right at it. That’s why it appears stationary, while the other stars seem to revolve around it. If you point a finger at Polaris you’ll be pointing north, and you can use that orientation to go in whatever direction you want.

Now, if you can measure the angle of Polaris above the horizon, you’ll also know your latitude. If the angle is 30 degrees, you’re at latitude 30 degrees. See, it’s easy. And once you can measure position, you just need to do it twice and record the time interval to find your velocity.

But celestial navigation works because we know how the Earth rotates, and that doesn’t help in a spacecraft. Oh well, can we just use the stars like you would use the cows on the side of the road? Nope. The stars are so far away, astronauts would need to travel for many, many generations to detect any shift in their position. Like the airplane flying over the sea, you’d seem to be stationary, even while traveling 25,000 mph.

But we can still use the basic idea. For optical navigation in space, a spacecraft can locate other objects in the solar system. By knowing the precise location of these objects (which change over time) and where they appear relative to the viewer, it’s possible to triangulate a position. And again, by taking multiple position measurements over time, you can calculate a velocity.

In the end, even though spaceships lack speedometers, it’s possible to track their speed indirectly with a little physics. But it’s just another example of how flying in space is really, totally different—and way more complicated—than driving or flying on Earth.

If those posts could be interpreted in any way as threats, Eversole would contact their hometown police, multiple security team sources say. “He would take it upon himself to reach out to someone somewhere and introduce himself as the CSO of Madison Square Garden and demand that the local PD take action,” the security veteran adds.

One teenager posted a tweet, and MSG security asked local law enforcement to visit him. “They scared the crap [poop emoji] out of some 14 year old kid in Colorado,” one MSG security staffer texted in a message we reviewed. Cops would at times ignore Eversole’s demands. He and his deputies would then “freak the fuck out when a PD somewhere would not play ball,” the second veteran continues.

Eversole would also allegedly push his subordinates to act more like municipal cops. He’d urge them to patrol the streets surrounding MSG, which is located in one of Manhattan’s more derelict neighborhoods, functionally acting as a second, ersatz police force—without formal permission of New York’s real one. “On many occasions, I was ordered to stop traffic, close sidewalks, and unlawfully detain individuals in the venue and demand identification,” Munn, the former security worker, wrote in his filing. Munn added that these orders were “against NY State/City laws without proper permits or NYPD’s authorization, which MSG did not maintain.” An NYPD spokesperson confirms that such authorization was never given.

Eversole would tell his teams to bust the guys selling knockoff merchandise and “remove scalpers and drug dealers daily, in areas outside and around MSG properties, without back up, communication, or assistance from MSG venue security or NYPD paid detail,” Ingrasselino alleged in his lawsuit.

Ingrasselino’s former colleagues emphasize that the work could be dangerous, possibly illegal, and in no way a normal task for a private security force. Ingrasselino, among others, claimed that a former NYPD assistant chief now working for MSG was once attacked by scalpers and sent to the hospital. In his filing, Munn claimed that during his time “overseeing all security aspects” of several Dolan properties, he had been “ordered to do many things I felt were unsafe, unethical, and illegal, all at the direction” of Eversole.

Ingrasselino also alleges in his suit that he was ordered to embed “in the middle of pro-Palestine or anti-Israel protests” that happened to be passing a Dolan venue. Other security sources say that they were not ordered to insert themselves into any demonstrations. But they confirm that they were asked to observe protests that went anywhere near a Dolan venue. Given those venues’ central location, it happened a lot.

Some protests would get special scrutiny. When the Professional Bull Riders tour came to the Garden, animal rights activists would at times gather outside, or in front of the MSG president’s apartment building. The leaders felt they were being singled out and surveilled.

Even people working for the state government found themselves in MSG’s sights.

In late 2022 and early 2023, when word about the lawyer bans began to spread and uproar over the face-recognition program was hitting a peak, the State Liquor Authority decided to look into it; per state law, according to the SLA, you’re not allowed to both serve booze and arbitrarily lock people out of your place. Dolan’s response may have been a touch over-the-top. He went on TV, held up a photograph of the then head of the liquor authority with the man’s phone number and email underneath, and told the audience to reach out to him, and “tell him to stick to his knitting.”

Consider the chief difference between living systems and electronics: The first is generally soft and squishy, while the latter is hard and rigid. Now, in work that could impact human-machine interfaces, biocompatible devices, soft robotics, and more, MIT engineers and colleagues have developed a soft, flexible gel that dramatically changes its conductivity upon the application of light.

Enter the growing field of ionotronics, which involves transferring data through ions, or charged molecules. Electronics does the same, with electrons. But while the latter is well established, ionotronics is still being developed, with one huge exception: living systems. The cells in our bodies communicate with a variety of ions, from potassium to sodium.

Ionotronics, in turn, can provide a bridge between electronics and biological tissues. Potential applications range from soft wearable technology to human-machine interfaces

“We’ve found a mechanism to dynamically control local ion population in a soft material,” says Thomas J. Wallin, the John F. Elliott Career Development Professor in MIT’s Department of Materials Science and Engineering and leader of the work. “That could allow a system that is self-adaptive to environmental stimuli, in this case light.” In other words, the system could automatically change in response to changes in light, which could allow complex signal processing in soft materials.

An open-access paper about the work was published online recently in Nature Communications.

A growing field

Although others have developed ionotronic materials with high conductivities that allow the quick movement of ions, those conductivities cannot be controlled. “What we’re doing is using light to switch a soft material from insulating to something that is 400 times more conductive,” says Xu Liu, first author of the paper and former MIT postdoc in materials science and engineering who is now an incoming assistant professor at King’s College London.

Key to the work is a class of materials known as photo-ion generators (PIGs). These can become some 1,000 times more conductive upon the application of light. The MIT team optimized a way to incorporate a PIG into polyurethane rubber by first dissolving a PIG powder into a solvent, and then using a swelling method to get it into the rubber.

Much potential

In the material reported in the current work, the change in conductivity is irreversible. But Liu is confident that future versions could switch back and forth between insulating and conducting states.

She notes that the current material was developed using only one kind of PIG, polymer (the polyurethane rubber), and solvent, but there are many other kinds of all three. So there is great potential for creating even better light-responsive soft materials.

Liu also notes the potential for developing soft materials that respond to other environmental stimuli, such as heat or magnetism. “We’re inspired to do more work in this field by changing the driving force from light to other forms of environmental stimuli,” she says.

“Our work has the potential to lead to the creation of a subfield that we call soft photo-ionotronics,” Liu continues. “We are also very excited about the opportunities from our work to create new soft machines impacting soft wearable technology, human-machine interfaces, robotics, biomedicine, and other fields.”

Additional authors of the paper are Steven M. Adelmund, Shahriar Safaee, and Wenyang Pan of Reality Labs at Meta.