20 ms from Toronto.
The one other thing I missed is to also think of designing a service oriented architecture. Every role that your system has, such as authentication (I'd use OAuth2), should be its own service. By using clearly defined APIs, it will make it easier to replace pieces of your system with new ones (even written in new languages), and it will give you an interface to write tests against for your tests.
As someone who has written an application that scales to over 1 billion requests per day, let me offer my thoughts.
Scaling your application should be as trivial as launching more application server nodes. If you can't add/remove application nodes painlessly, you've probably done something wrong like keep state on them (this includes sessions).
Don't worry about scaling your application layer at all (within reason). You can always throw more machines at the application side in a pinch, and for a long while it will be cheaper to add servers than to hire someone. When your application servers are costing you more than a salary, hire someone to find the hotspots in the code and make them faster. Until then it's a waste of your time.
Scaling state, aka your datastores, is where the challenge lies. You need to spend a large amount of time sitting down and analysing every operation you plan to do with your data. SQL is great for a lot of things, but you will eventually run into a point where heavy updates make SQL difficult to scale. Mind you, decent hardware (lots of cores, RAM, and SSD) running MySQL should scale to several thousand active users if your queries are not expensive. The Galera patches to MySQL (incorporated into Percona XtraDB Cluster and MariaDB) can give you true high-availability, but you will still have write-throughput limitations.
I would also highly recommend you look into Cassandra (especially 1.2+, with CQL 3), which was built from the ground up to scale thousands of low end machines that often fail (if you can't tolerate hardware failure, you messed up). Cassandra is more limited in the kinds of queries you can execute, more relaxed with data consistency, and more thought is needed ahead of time. On the other hand, it can also be used for global replication, which is something you are interested in. At the very least, having a good understanding of its data and query model will open your mind to the kinds of tradeoffs that must be made to enabling scaling.
Contrary to what others are saying, you are correct to think about scaling now before you even start! Doing a rewrite is costly and expensive in money and time. Why set yourself up for that? Planning for scale before you start is the best time! If you start with a scalable datastore like Cassandra, and structure all your queries to work within its model, it is no more work than doing things in SQL, and you're way ahead of the game!
The most important part is spending time modeling how you will access your data. Think about how you'll avoid hot spots (which make scaling writes difficult), and think about how to make reads fast by reading as little as possible. Think about caching, and how you'll invalidate the cache of a piece of your data without having to invalidate caches for things that didn't change. (Think about updating on data ingestion instead of running statistics later.) If you can't avoid hot spots, make only small reads, and cache independently, you are not done.
Even the high reading of 2.9 microsieverts/hour in that video isn't that bad for a short duration.
The naturally radioactive beaches of Guarapari, Brazil are 10-15 times hotter than that: http://www.youtube.com/watch?v=RvgAx1yIKjg
Even in a large plane passengers make up a significant percentage of the total flying weight. Airline companies just average the cost.
There is gold everywhere, but yes, fault lines are a great way to find certain kinds of gold deposits. If you want more information on why gold ends up where it does, I highly recommend a series of videos put out by the Sprott Group on ore deposists.
SpaceX has uploaded the CRS-2 launch video.
Right now I'm carrying a fair amount of extra weight, but even when I was trim my temperature preferences were the same (I took the swim at the skinniest point in my adult life when I was buying shirt to fit my chest).
It wouldn't surprise me if I had one or more of these mutations.
I find temperatures above 21C unpleasant. In December, I slept a couple nights in -25 temperatures in a -12 rated sleeping bag and was perfectly comfortable. I rarely wear a jacket above 0. I've taken a 45 minute casual swim in 10 water in nothing but shorts and felt a little chilled but fine (though it was sunny).
But I pay for it in the summer. Once it hits 23 my brain slows down. Around 26 it completely shuts off. I've experienced temperatures up to 40, but I'm glad those days are rare.
It's easy for me to overheat. I went on a winter hike in -15 weather and ended up getting moderate hypothermia -- because I left dressed in a "normal" amount of winter wear and sweat my clothing through. I was steaming. Thankfully I had a change of clothes, and two hours in a -7 sleeping bag got me warmed back up to normal.
People think I'm weird for enjoying -30. But I'd much rather have that than 30. I still find it odd that much of the world lives in near-constant 30 and find those high temperatures comfortable.
It's not exploitation if people choose to work those jobs, i.e. they consider working the job better than all their other options. It's not just the wage they make: it's a lot easier to work a job than to build a business, and that's why so many choose to work jobs.
There's a bug in your code: I think you meant && not ||.
Growing up at 54Â N, the "daylight" colour temperature setting on monitors never made sense to me. The closest to daylight was 9300K. It never made sense until I spent a week in LA one January and saw that the sunlight really was 5800K orange when you are that far south.
I'm Canadian. If you make $90k, your marginal tax rate is most likely over 40%, plus the property taxes, the sales taxes, etc., from enjoying your earnings easily push your marginal rate over 50%.