I'm not saying Europeans have something in common but if you live on the continent that is known as Europe then you are European. You're confusing this with the European Union.
And besides the language have so much in common either. Due to the two-party political system, the US is so divided that it's not a true union either. The bigger the country/union, the more opinions, mindsets, ideologies you are going to have. This makes governing difficult and political differences are guaranteed. But the economic gains from the Euro has been tremendous. The media always talks about Greece, Spain, Ireland etc. But if you look at the rest of the northern countries and countries like Germany and Austria economic gains are evident. The European Union is not necessarily a bad thing, it's just that some people had the wrong expectations. If you think the Euro is an illusion then you need to watch something besides Fox News. The fact of the matter is that the Euro is currently the world's largest currency in terms of circulation. There are more Euros in circulation than US dollars. The trend is continuing this way and with China and the Arabian peninsula investing more and more in Europe, they will have more Euros and will ultimately help in establishing the Euro as the world currency. You probably won't believe me, but take a look at this post in 10-15 years and you'll see.
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It's just ironic how the world's most famous/biggest/important scientific companies are based in the US and they of course use the metric system. I'm not saying that the US system is horrible or anything like that. But there comes a point where one has to realize that a better alternative exists that the rest of the world is using.
Now from a practical perspective, the US system is horrendous. That's why Bio/Chem/Physics/Math/Engineering all use Metric.