Microscopic turbulence in plasma can trigger macroscopic structural changes. In complex physical systems, such cross-scale interactions—between different spatial and temporal scales—are known as multiscale coupling. To the best of their knowledge, Prof. Yong-Seok Hwang’s team, together with the Asia Pacific Center for Theoretical Physics, has now experimentally proven this phenomenon for the first time.

The work is published in the journal Nature.

The breakthrough resolves a long-standing puzzle in plasma physics, with implications for both fusion energy development and the study of astrophysical plasmas.

Seoul National University College of Engineering announced that a joint research team led by Prof. Yong-Seok Hwang from the Department of Nuclear Engineering, in collaboration with the Asia Pacific Center for Theoretical Physics (APCTP), has experimentally demonstrated the phenomenon of multiscale coupling in plasma—a long-standing puzzle in plasma physics—through the integration of fusion experiments and astrophysical plasma theory.

Initiated under the proposal of Prof. Hwang, who holds appointments in the Department of Nuclear Engineering and the Department of Energy Systems Engineering, the study was conducted solely by three Korean researchers.

The team included Dr. Jong Yoon Park, BK Assistant Professor at SNU and first author of the paper, and Dr. Young Dae Yoon, theoretical physicist at APCTP and corresponding author. This achievement, accomplished entirely by domestic researchers, is recognized as a milestone that significantly elevates Korea’s standing in global plasma science and technology research.

For plasma physicists, plasma—often called the “fourth state of matter,” distinct from solids, liquids, and gases—presents the formidable challenge of explaining how microscopic instabilities can drive macroscopic structural changes. The problem of multiscale coupling has therefore remained one of the most fundamental and long-standing issues in the field.

Plasma, however, is not only the essential medium for nuclear fusion reactions but also the predominant state of matter in the universe. Accordingly, understanding multiscale coupling in plasma has long been considered critical for both advancing fusion energy technology and unraveling the origins of the universe.

The team of Dr. Park and Dr. Yoon analyzed experimental data obtained from SNU’s fusion device and verified their findings through particle simulations using the KAIROS supercomputer at the Korea Institute of Fusion Energy. Their results proved that when microscopic magnetic turbulence is triggered, magnetic reconnection occurs effectively, inducing macroscopic structural changes within plasma.

The joint research team demonstrated for the first time that microscopic magnetic turbulence, deliberately induced by a strong electron beam, can increase plasma resistivity, thereby driving magnetic reconnection and ultimately producing large-scale structural changes—a direct experimental realization and proof of multiscale dynamics in plasma.

The study is particularly significant as an interdisciplinary achievement, combining experimental operations of Seoul National University’s fusion device with theoretical simulations conducted at APCTP.

This achievement also reflects the sustained efforts of Seoul National University and APCTP to provide early-career researchers with opportunities at an international level and to foster interdisciplinary collaboration. It stands as a representative case of advancing the global competitiveness of domestic researchers and nurturing future leaders in science and technology.

Dr. Jong Yoon Park, BK Assistant Professor at SNU, noted, “This outcome was only possible through countless discussions and debates between experts in fusion and theoretical physics, who started from different interests but ultimately arrived at common ground.

It is particularly meaningful in that it offers new clues to understanding the onset of magnetic reconnection, a process that plays a key role in cosmic phenomena such as solar flares and geomagnetic storms.”

Dr. Young Dae Yoon of APCTP added, “We hope this research will not only expand the framework of interpretation in plasma physics but also serve as a foundation for the development of new fusion technologies.”

Apple’s software design strives to be intuitive, but each iteration of iOS contains so many additions and tweaks that it’s easy to miss some useful iPhone settings. Apple focused on artificial intelligence when it unveiled iOS 18 in 2024 and followed it with Liquid Glass in iOS 26 (the name is now tied to the following year), but many intriguing customizations and lesser-known features lurk beneath the surface. Several helpful settings are turned off by default, and it’s not immediately obvious how to switch off some annoying features. We’re here to help you get the most out of your Apple phone.

Once you have things set up the way you want, it’s a breeze to copy everything, including settings, when you switch to a new iPhone. For more tips and recommendations, read our related Apple guides—like the Best iPhone, Best iPhone 16 Cases, Best MagSafe Accessories—and our explainers on How to Set Up a New iPhone, How to Back Up Your iPhone, and How to Fix Your iPhone.

Updated September 2025: We’ve added a few new iPhone tips and updated this guide for iOS 26.

Enable Call Screening

Make cold-calling pests a thing of the past with Apple’s new Call Screening feature. Go to Settings, Apps, and select Phone, then scroll down to Screen Unknown Callers and select Ask Reason for Calling. Now, your iPhone will automatically answer calls from unknown callers in the background without alerting you. After the caller gives a reason for their call, your phone will ring, and you’ll be able to see the response onscreen so you can decide whether to answer. You should also make sure Hold Assist Detection is toggled on, so your iPhone detects when you are placed on hold, allowing you to step away, then alerting you when the call has been picked up by a human.

Turn on RCS

The texting experience with Android owners (green bubbles) got seriously upgraded last year when Apple decided to finally support the RCS messaging standard (rich communication services). RCS has been around for several years on Android, and allows for a modernized texting experience with features like typing indicators, higher-quality photos and videos, and read receipts. Group chats may still be wonky, but they’re still a significant improvement. However, on a new iPhone, RCS is disabled by default (naturally).

Make sure you turn it on for the best messaging experience. Head to Settings > Apps > Messages > RCS Messaging and toggle it on.

Customize the Control Center

Apple via Simon Hill

Swipe down from the top right of the screen to open the Control Center, and you’ll see it’s more customizable than ever. You can tap the plus icon at the top left or tap and hold on an empty space to open the customization menu. Here you can move icons and widgets around, remove anything you don’t want, or tap Add a Control at the bottom for a searchable list of shortcut icons and widgets you can organize across multiple Control Center screens. You can also customize your home screen to change the color and size of app icons, rearrange them, and more.

Change Your Lock Screen Buttons

You know those lock screen controls that default to flashlight on the bottom left and camera on the bottom right? You can change them. Press and hold on an empty space on the lock screen and tap Customize. Tap the minus icon to remove an existing shortcut, and tap the plus icon to add a new one. You can also change the weather and date widgets, the font and color for the time, and pick a wallpaper. One of the clocks will even stretch to adapt to your wallpaper.

Extend Screen Time-Out

Apple via Simon Hill

While it’s good to have your screen timeout for battery saving and security purposes, I find it maddening when the screen goes off while I’m doing something. The default screen timeout is too short in my opinion, but thankfully, you can adjust it. Head into Settings, Display & Brightness, and select Auto-Lock to extend it. You have several options, including Never, which means you will have to manually push the power button to turn the screen off.

Turn Off Keyboard Sounds

Apple via Simon Hill

The iPhone’s keyboard clicking sound when you type is extremely aggravating. Trust me, even if you don’t hate it, everyone in your vicinity when you type sure does. You can turn it off in Settings, Sounds & Haptics by tapping Keyboard Feedback and toggling Sound off. I also advise toggling off the Lock Sound while you’re in Sound & Haptics.

Go Dark

Apple via Simon Hill

Protect yourself from eye-searing glare with dark mode. Go to Settings, pick Display & Brightness, and tap Dark. You may prefer to toggle on Automatic and have it change with the sun setting, but I prefer to be in Dark mode all the time.

Change Your Battery Charge Level

Apple via Simon Hill

If you’re determined to squeeze as many years out of your iPhone battery as possible, consider changing the charging limit. You can maximize your smartphone’s battery health if you avoid charging it beyond 80 percent. The iPhone’s default is now Optimized Battery Charging, which waits at 80 percent and then aims to hit 100 percent when you are ready to go in the morning. But there’s a slider you can set to a hard 80 percent limit in Settings, under Battery, and Charging. If it bugs you, this is also where you can turn Optimized Battery Charging off.

Turn On Adaptive Power Mode

Apple via Simon Hill

If you get worried about running out of battery, go to Settings, Battery, and scroll down to select Power Mode, where you can toggle on Adaptive Power. This mode will detect when you are using more battery life than normal and make little tweaks, like lowering display brightness or limiting performance, to try and get you through to the end of the day.

Set Up the Action Button

Folks with an iPhone 15 Pro model, any iPhone 16 model, or any iPhone 17 have an Action Button instead of the old mute switch. By default, it will silence your iPhone when you press and hold it, but you can change what it does by going to Settings, then Action Button. You can swipe through various basic options from Camera and Flashlight to Visual Intelligence, but select Shortcuts if you want it to do something more interesting. If you’re unfamiliar, check out our guide on How to Use the Apple Shortcuts App.

Customize Camera Control

Photograph: Julian Chokkattu

The iPhone 16 series debuted Camera Control, a physical button that sits below the power button and triggers the camera with a single press. When you’re in the camera app, pressing it will capture a photo, and a long-press will record a video. Pressing and holding Camera Control outside of the camera app triggers Apple’s Visual Intelligence feature (sort of like Google Lens). But what I find most annoying is Camera Control’s second layer of controls: swiping. You can swipe on the button in the camera app to slide between photography styles, zoom levels, or lenses. It’s neat in theory, but way too sensitive.

Comparing Our Favorite Bamboo Bedding

Terminology to Know When Shopping

Confused by the terms used to describe bamboo bedding? Here’s a quick breakdown.

Bamboo type: You’ll see bamboo rayon, viscose, or lyocell listed for the bamboo, which explains what method was used for turning the bamboo into fibers that could become sheets. Rayon is the cheapest, while viscose is a slightly better production process, and lyocell is the most ideal process (but still not a perfect one, and usually the most expensive).

Certifications: Some companies will label bamboo sheets as organic, using certifications like Oeko-Tex. You can learn more about organic certification terms here to understand what they each mean, and our thoughts on organic bamboo in our FAQs below. You might also see FSC-certified, which means it was sourced through sustainable forests certified by the Forest Stewardship Council.

Honorable Mentions

Cariloha Classic Bamboo Sheets for $239: Cariloha’s Classic Bamboo Sheets have a twill weave, which has a diagonal thread pattern and doesn’t sound as soft as a sateen weave that has a three-over-one pattern. But these sheets still felt super soft, and the softness difference compared to the pricier Retreat Sheets ($339) was minor for such a big price difference. There’s no corner straps, though.

Cariloha Retreat Bamboo Sheets for $339: These sheets are super soft and silky and use lyocell fabric to be more sustainable. They’re a similar softness to the brand’s cheaper sheets, but if you want to prioritize eco-friendly sheets, lyocell is a good option (though not a perfect carbon-neutral solution). I also really like the included straps, but you can find those on cheaper sets like the Luxome sheets I recommend above.

Ettitude Luxe Sheet Set for $470: These sheets are fantastically soft and use a combination of bamboo lyocell and bamboo “biochar” to make them antifungal and odor-resistant. They ran a little warm for my liking, but if you’re looking for something to keep odors and fungi away, these could be the splurge for you. Ettitude previously called these Airy+ instead of Luxe, but both use a combination of lyocell and biochar.

Honeydew Sheets for $230: These sheets felt a little stiff at first but softened up a bunch after washing. They also come with a securing strap, so they’re a good option for taller mattresses. The only downside is that they’re only available in two colors, but if you want white or a nice dark gray, you’re in luck.

My Sheets Rock the Regulator Sheet Set for $199: These sheets are super soft. They promise to regulate your temperature, but I found myself waking up a little too warm some nights. If you aren’t a hot sleeper, these are overall soft, comfortable sheets to sleep on.

Pom Pom at Home Bamboo Sateen Sheet Set for $368: These are good bamboo sheets, but for the price, we were more impressed by others we tested.

Quince Linen Bamboo Bundle for $255: This set would have been a pick if it were still available. It’s a fantastic combination of linen and bamboo that gets the best of both worlds: the softness and cool touch of bamboo with the structure and airflow of linen. It’s a great pick for hot sleepers—if it resurfaces, buy it!

Quince Bamboo Sheet Set for $130: Quince makes some solid sheets, and these bamboo ones are super soft. They’re a little heavy for me as a hot sleeper, but otherwise come in a nice range of colors and have an Oeko-Tex certification, meaning no harmful chemicals were used. Quince also says the bamboo is organic, but there aren’t any certifications to confirm that (more below on our thoughts on organic bamboo bedding).

Sunday Citizen Bamboo Sheet Set for $109: WIRED reviewer Louryn Strampe found these sheets to be super soft and fantastic to sleep on. But even with the claimed deep pockets, they tended to pop off her mattress, and other picks like Luxome’s sheets feature straps that will avoid that problem.

FAQs

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