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Richly illustrated with the images from observatories on the ground and in space, and computer simulations, this book shows how black holes were discovered, and discusses what we've learned about their nature and their role in cosmic evolution. This thoroughly updated third edition covers new discoveries made in the past decade, including the discovery of gravitational waves from merging black holes and neutron stars, the first close-up images of the region near a black hole event horizon, and observations of debris from stars torn apart when they ventured too close to a supermassive black hole. Avoiding mathematics, the authors blend theoretical arguments with observational results to demonstrate how both have contributed to the subject. Clear, explanatory illustrations and photographs reveal the strange and amazing workings of our universe. The engaging style makes this book suitable for introductory undergraduate courses, amateur astronomers, and all readers interested in astronomy and physics.
Tuesday. 7.45am. Your commute is going well. No delays so far. Of the 15 emails awaiting your attention, you’ve answered eight. Only seven more to go. But these are tricky ones. You dip into your phone's browser, download a file from your work's server, scan it to ensure it has the data you need. Back into email. ‘Hi Sarah, sales were up 3.4% in March. Let me know if you need further info.’ Back into the browser. Apparently, there was an angry message posted on Twitter last night. You find it, look through the profile of the customer, copy the message. Back into email. ‘Hi James, some flak on Twitter last night. I’m pasting the message. Please resolve.’ You see that Sarah has replied already. She wants to know what sales were in March for the last five years. You’ll be arriving soon. No time for this. ‘Sarah, I’ll come back to you in twenty: just arriving on train.’ James has replied also. ‘Who wrote this tweet?’ Back into the browser. No internet connection? You look up: other commuters are looking up and around, confused. Seems the train's Wi-Fi has gone down. Only then do you notice: you missed your stop.
For many people today, the separation of time spent at work and time spent away from work has disappeared. Before the digital revolution, a fair few workers would have worked during their commute: reading a report perhaps, or preparing notes in advance of an afternoon meeting. But there were technological limits to this type of activity. With no email, your connection to a Sarah or a James hinged on meeting them once you arrived in the office or giving them a call from your desk. While reading a report, you weren't receiving ‘pings’ asking you to handle some other matter. Nowadays, technology facilitates and encourages multiple simultaneous conversations across numerous platforms. Once you’re online – which could be from the moment you wake up – work activities can easily suck you in: answering emails, checking technical reports, looking for updates, requesting information from colleagues, editing files, and more, all while you make coffee, eat breakfast, get the kids dressed, take them to school, and head for the train.
Wednesday. It's 10.30am and you’re heading out to grab a coffee at your favourite spot, Lou's Café. Swiping your staff card, you exit the building, passing the security booth, glancing up at the cameras watching you leave. You tap your phone to hail a rideshare cab, which arrives just a minute later and takes you toward the town centre. At the coffee shop you pay with a tap of your debit card, collecting points with your loyalty card. While you wait for the coffee, you notice a screen near the milk which flashes an ad directed right at you, your name at the top: ‘Make warts a thing of the past. Get 20% off our cream at Chem-Care. Scan the QR code for an in-store voucher.’ That was embarrassing. You wish these ads were less intrusive. Checking your phone out of habit – why is this coffee taking so long to arrive; you’ve been waiting a minute already – you see another ad for Chem-Care, which is now offering a twofor-one on wart cream if you tweet about Lou's Café.
In today's digital world, the line between your public persona and private affairs is blurring. The scenario above is an exaggeration: chances are, an imaginary company like Chem-Care wouldn't actually direct such a personal ad in public like that, although tying your purchase in one venue to your location in another is already happening. What you think is your private business – you have a couple of warts, they’re annoying, you’re bothered by them, and you’d rather not advertise this to others – is now a business opportunity that algorithms can identify and use as the basis for steering your future purchases in a specific direction. Massive investments are being made right now by all sorts of companies to capitalize on and monetize these sorts of opportunities. Whether it is information based on your online search activity or the places you frequent when you’re out spending money, you’re now just one of billions of other targeted humans.
Digital life demands and creates data shadows and footprints made up of trillions of our individual responses to the prompts and invitations playing out on our devices, the services located within them, and the world at large.
Thursday. It's 1pm. You’ve been trying to change how you work. You arranged to meet a colleague for lunch by emailing her yesterday, rather than contacting her via WhatsApp today. You’ve spent the morning working in a focused way, ignoring email and messages, and staying away from social media. Before heading out of the office you’ve just caught up on those communications in a quick intensive session and placed your phone on silent. Lunch feels a little strange because you leave your phone in your pocket and not on the table next to your plate. You describe the morning to your friend: how you read a book on the train for the first time in years (and how odd that felt when everyone around you was on their phone); how you’ve purposefully been using a new web browser that hides your IP address; and how you’re more carefully curating what you share online. She doesn't seem too impressed, but it has actually felt like a good move to you; certainly, it's been different and, yes, it's been a little bit inconvenient. But it has also felt liberating.
Hopefully this scenario sounds appealing and achievable. We think it starts to set out what a slow computing day might look like. As we pointed out in Chapter 1, slow computing is a means to address the various issues that acceleration and data extraction create. It seeks to do this in a way that prioritizes and protects your needs and interests, and creates public good for society as a whole. Practising slow computing requires individual and collective actions: people making decisions to change how they lead their digital lives by considering and changing their own situations, and pooling their actions and drawing on the diverse actions of others.
This chapter focuses on tactics you individually can use to fulfil the strategy of slow computing. It is about taking ownership of the issue and being proactive in tackling acceleration and extraction at a personal level. To that end, we set out some interventions aimed at slowing down your computing. We emphasize reconfiguring the time you spend on your digital participation, while curating and limiting the extent to which you leave data footprints and cast data shadows. Adopting these ideas can be empowering because it can give you back a degree of control.
Sunday. 10pm. The week is over. You’ve done well. You’ve managed to move away from frantic messaging and updating without giving up being online. You’ve taken note of your data trails and adjusted your practices along with others to slow down and evade excessive data extraction. Life isn't perfect all of a sudden, but you’ve been taking part in a reassessment of your digital life and you’ve some more control now. The weekend has been relaxing without being constantly tethered to the internet. Tomorrow is Monday and the day will start again at 6.30am. The question is whether the working week will be as crazily busy and stressful as usual, or whether it’ll be possible to slow it down and be calmer, more focused and balanced. You think about checking your email and social media accounts, but decide it can wait until tomorrow. There's no point ruining a night's sleep by worrying about the contents of a message or the state of the world according to Facebook. In fact, you think you might give social media a break for a few days. The world is not going to end because you only log in a couple of times a week. You turn off the light and quickly fall into a deep sleep.
This doesn't sound too bad, does it? You’re still feeling the joy of computing, but more on your terms. You’ve achieved some kind of balance between acceleration and data extraction and getting on with your everyday life. You’ve found some harmony between work and home. You’re living a slow computing life. You’re no longer a slave to your devices; you’ve more freedom from the digital leash. You’re less harried, stressed and distracted. You’re not careening through life, but doing more of the things you want, when you want to, and you’re not as beholden to the demands of others. You feel like you have more time for yourself – for rest, leisure, personal interests and goals, and contemplation. You’re doing fewer things, but you’re enjoying what you do more. In fact, you feel like you’ve become more productive and your work has improved. It seems like you’ve got more control over your digital footprints and shadows. You’re still using services, but you have a hand in deciding what data are gathered. You have a better sense of your rights and an understanding about how to challenge malpractice.