We measure calories in food by burning it in a lab and calculating the exact energy given off. Very precise. What we don't measure is how many pieces of that cob of corn I ate for dinner will pass through to my stool.
And I'll accept the comment that activities burn calories at predictable rates (they don't across populations -- look at exercise adaptation) but they can per individual. But treating the consumption of calories and the expenditure of calories as independent variables seems foolish. For an absurd comparison -- do you think my Caloric consumption over the next 24 hours would be identical if I consumed 10 calories of chocolate or 10 calories of amphetamines?
Physics works. A calorie is a calorie. But pretending that the human body treats all calories the same as a calorometer seems foolish.
All correct, agreed. What it means is, there is some level of exercise that will consume enough calories to exhaust ready supply. Then weight loss occurs.
The silliness begins when folks start to bargain. How little exercise can I get away with? How can I eat a lot and not gain weight? Its this lazy concern that occupies everybodys thoughts and behaviors. They write whole books about it.
When in fact, if they'd get off their lazy butts and exercise, really exercise, they could forget about all those details. Physics could work for them.
And by exercise I mean ride that bike 20 miles over the lunch hour. With some stiff hills involved. Really exert yourself. But few want to do that. They want to ride a recumbent 5 miles on the flat and then eat 3 hamburgers. And complain that exercise clearly doesn't work because they're not losing weight.
Its astonishing how little exercise most folks have ever done in their lives. I'd go this far: most folks have never exercised. They've warmed up, and then stopped when they hit the point their muscles feel it. I know this - I've taken folks hill-riding and had them stop. "Something's wrong. I feel funny. My heart rate is up and my muscles are complaining". They'd never gotten aerobic in their entire lives, and were afraid of the feeling.
From personal experience, and this was some years ago, I've found that on a high carb, high fat diet e.g. breakfast: beans, bacon, eggs, toast. lunch: sandwich with deli meat, cheese, mayo. supper: bread, veg, and meat, plus a few cups of coffee and a beer thrown in caused pretty rapid weight gain (30lbs.) with what I would call a normal amount of activity, walking a reasonable distance to and from work, intentional exercise 2 - 3 times per week, some activity on the weekends but the rest of the time spent at a desk or on a couch.
After taking a summer job doing manual labour that involved constant, intense activity (lots of shovelling, sweeping, lifting, walking, pushing and pulling) from 8 AM to 1 PM every day I saw a complete reversal in weight while maintaining the same diet.
So from my own experience, it is absolutely possible to eat a fairly heavy diet and lose weight. It all depends on balancing your intake with the amount of energy you consume during the day. The only problem is that it takes a lot of heavy physical work to use those calories and the exercise regimen that most people assume comes no where near to what it takes to use up the amount they take in.
As far as quitting before you actually really start exercising, there was a good quote by Muhammad Ali circulating the other day  "I don't count my sit-ups. I only start counting when it starts hurting. That is when I start counting, because then it really counts. That's what makes you a champion."
It entirely depends on your effort level. To say 'biking' burns 530 calories per hour seems precise. But a racer can burn 5000 calories. And you can burn everywhere in between those numbers, depending on your exertion level and the course.
Where do parents fit in this utopia of yours? I've got 2 car seats and a pram and some toys in my car in the driveway. Personally owned transport makes more sense for people who have to move things other than themselves and a laptop (tools, babies, etc)
Utopia? Did you read the last sentence of my comment? I think a self-driving car future is a future with disempowered individuals in a neo-feudal transportation world. It sounds terrible to me, but I think it's likely to happen (at least in the US). There are practical and economic advantages in that future and some large existing economic players who can profit from it.
I'd tend agree with your comment in the short term. Moving my daughter's child safety car seat would be a pain, for sure. Longer-term I would expect to see modular standards emerge for child safety car seats. You lock your child's seat into the standardized base that's hiding under a seat cushion in the back of the car. There are already stroller / pram systems that incorporate the child safety car seat, so I could expect that market to boom, too.
Moving things besides yourself is something a lot of people in urban areas already do with public transit. With a private autocar service it's more likely that you'd get more space than on a subway or bus, so I'd think it would be even easier to move more than just yourself. I would expect a rental option to let you keep the car with you, as opposed to it returning to the fleet when you reach your destination.
That doesn't currently happen? I'm in Aus - so things are different - but certainly here there's an awful lot of pubs with only the one mega brewers beers on tap (aka - either SABMiller or Lion Nathan). In the same ways that most smaller stores have either coke or pepsi but not both. They are not forced they are just incentivised.
I would imagine similar to a SAML Persistent Name Alias.
facebook knows who you are - but they just send a non-identifying string/GUID to the service who is trying to log you in. This is a consistent ID (so that service can build a profile) - but it does not contain any identifying data.