Oh, m_0 is rest mass, in case you didn't know that, and m is the relativistic mass.
Actually it is more correct to write it as:
E^2 = p^2c^2 + m^2c^4
"relativistic mass" is a very bad concept to learn (something which even Einstein pointed out). A far better way to think about it is that our classical definition of momentum is just a low energy approximation of true momentum. The mass of a particle, just like its charge, is something that does not change.
Hey "cdn-programmer" I live in Canada too and I love it there as well but you really need to get out a bit more. May I suggest a short holiday to a place called the Caribbean?:-)
Anyone noted the irony that we don't actually use the euro in England? My guess is that whe we do the plural we be "euros" and all the declarations to the opposite will be about as effective as king Canute.
Rogerson says that as far as his lectures are concerned, his students are free to record anything that comes out of his mouth and use it for their own purposes, so long as they don't profit from it.
That's a sad comment on the usefulness of his lectures!:-)
Just a nitpick.... I think the redshifting would be irrelevant. If you were going fast enough to redshift the gammas behind you into harmlessness, you would be fried by the blueshifted radiation in front.
Well....to nitpick your nitpick the intensity of star light is a LOT less than the gamma ray burst (or else there would not be a problem)
I suppose we could make a REALLY good predictive model of when astronomical objects are likely to do this - and predict the arrival of a gamma ray burst in time to do something about it. But what could we possibly do?
According to the article the burst has to originate within 6,000 light years...so if we work out what causes them all we have to do is scour the near vicinty for the pairs of neutron stars required (if that's it). Not trivial but not impossible either. Once we've done that we will likely be able to predict when the burst will occur.
...but this radiation will be expanding out equally in all directions from the source.
Not neccessarily - it depends on the source.
we'd have to high-tail it outta here at close to the speed of light in order to get far enough away for the inverse-square law to have an effect.
Actually you don't need to worry about the inverse square law if you are going that fast. Red shift will make the gamma's harmless.
...and a mile of salt water doesn't attenuate the energy enough
If you actually read the article (but this is Slashdot so what am I talking about!) you'll see that the effect is caused by interaction between the gammas and the ozone layer. If the gammas had enough energy (or intensity) that a significant dose penetrated 1.6km of water the heat load would actually be what would kill you and not the radiation itself! Such a massive heat load would have melted rocks etc and, I would guess, leave a significant geological record. In any case there is no way the burst could penetrate the earth and affect life on the otherside directly which you scenario would require - otherwise no more than 50% of the earth could be affected and the seas far less than the land due to the water shielding.
The other option is for Microsoft to just stop selling and supporting software in the EU. I honestly believe the EU would recant if MS pulled something like this.
...or not...could Microsoft really afford to have the EU (which has a population greater than the US) being forced to use a different OS? Sure it would be an expensive and difficult change which nobody wants to force but the results would be catastrophic to MS. If, for example, every company in the EU was forced to use Linux (or OSX) it would become extremely serious competition to Windows outside the EU.
My Grandma told me something similar. "You can go anywhere with a white shirt and a smile." Shortly after I followed that advice, I learned that "pants" should definitely be added to that list.
You'd be even more successful if you added trousers as well
Well, I must say that the old axiom 'the grass is always greener on the other side' must hold true here.
As a European who's lived on both sides of the US-Canada fence I can definitely say that the grass is greener on this (the Canadian) side....at least when it's not buried under snow.
We don't even have a concrete bill of rights that can't be overriden in many regards by our legislature.
I would argue that this is what makes the Canadian system superior to the US system. If you look at the US system the only people who can get laws struck down as being "unconstitutional" are those who can afford exorbitant legal fees. Thus the laws which disadvantage or ideologically irritate the rich seem to be those that are most frequently challenged.
In Canada the government can override challenges for 5 years at a time. Thus at least the guy on the street has someone (in theory at any rate) that can effectively represent him/her. It certainly helps to prevent individual people or firms "forcing" their view point. It's not a perfect system but it is the best I've seen: a good compromise between an absolute constitution like the US and not having one at all like the UK.
Canada reminds me of the videogame company that releases their product later so they don't make the mistakes of their competition and ends up with a superior result!
...with one slight difference: we have definite proof that Canada exists.
On the other hand with that many degrees you have to wonder how much focus the guy has and whether he really has any interest in _doing_ research as opposed to learning about what other people have done.
Even if I buy that could you explain the new "missile defence" system then? Given the stellar success of the tests so far if anything its encouraging rogue states. Personally I think there is somewhat of a delusion in Washington that these things really work.
This may be a strange concept to you, but for many people in the world, freedom and democracy are not their top priorities. Often, security and prosperity trump it.
Speaking as a European I don't see why any American would find this a strange concept given the outcome of your last election.
I like the way some people assume doctors are not allowed to have a life. It's ok to call the doctor whenever you like, day or night, but it's not ok for the doctor to go out and watch a movie?
No, like the rest of us doctors are allowed to have a life when they are not working. My dad was a GP and would never dream of going to watch a film when he was on call. Not only is it disruptive to everyone else but you can't watch the film either if you are dealing with a call. Not only that but is the doctor's mind really going to be on the call or what is going on on the screen? As a patient I'd switch doctors if I found mine displaying such a gross lack of professionalism.
Hydrogen IS an energy source...you just need to remember that there is more than one way to burn hydrogen. Extract some deuterium from sea water, put it into your fusion reactor, use the energy to electrolyze more sea water to get hydrogen for your fuel cells (and more deuterium for your reactor) and voila - a true hydrogen based economy.
Now if we can just get that fusion reactor to work...
Yeah, nothing wrong with doing 40 in a 25 mph zone. After all, instead of having 5 seconds to react to a kid running into the street you have less than 2 seconds.
The solution to this is to teach kids not to run into the middle of the road. I was amazed at the ridiculously low speed limits around schools in the US. What happens when these kids grow up - they encounter traffic at real speeds and get killed?
Slashdot Mirror
Actually it is more correct to write it as:
E^2 = p^2c^2 + m^2c^4
"relativistic mass" is a very bad concept to learn (something which even Einstein pointed out). A far better way to think about it is that our classical definition of momentum is just a low energy approximation of true momentum. The mass of a particle, just like its charge, is something that does not change.
Hey "cdn-programmer" I live in Canada too and I love it there as well but you really need to get out a bit more. May I suggest a short holiday to a place called the Caribbean? :-)
Anyone noted the irony that we don't actually use the euro in England? My guess is that whe we do the plural we be "euros" and all the declarations to the opposite will be about as effective as king Canute.
To be pedantic that would still make them superconductors..."better than existing superconductors" would be a more accurate statement.
I thought the whole point of skype was that it could function well behind firewalls?
Try reading the article or even the Slashdot story - it doesn't run on Linux, only Windows!
Our chief weapon is fear, fear and uncertainty. I mean our two waepons and fear and uncertainty, fear, uncertainty and doubt.
Argghhh!! Amongst our weapons we have fear, uncertainty and doubt...and lots of lawyers!
Rogerson says that as far as his lectures are concerned, his students are free to record anything that comes out of his mouth and use it for their own purposes, so long as they don't profit from it.
That's a sad comment on the usefulness of his lectures! :-)
Nah...in might be improbable but infinitely improbable?
Well....to nitpick your nitpick the intensity of star light is a LOT less than the gamma ray burst (or else there would not be a problem)
According to the article the burst has to originate within 6,000 light years...so if we work out what causes them all we have to do is scour the near vicinty for the pairs of neutron stars required (if that's it). Not trivial but not impossible either. Once we've done that we will likely be able to predict when the burst will occur.
Not neccessarily - it depends on the source.
we'd have to high-tail it outta here at close to the speed of light in order to get far enough away for the inverse-square law to have an effect.
Actually you don't need to worry about the inverse square law if you are going that fast. Red shift will make the gamma's harmless.
If you actually read the article (but this is Slashdot so what am I talking about!) you'll see that the effect is caused by interaction between the gammas and the ozone layer. If the gammas had enough energy (or intensity) that a significant dose penetrated 1.6km of water the heat load would actually be what would kill you and not the radiation itself! Such a massive heat load would have melted rocks etc and, I would guess, leave a significant geological record. In any case there is no way the burst could penetrate the earth and affect life on the otherside directly which you scenario would require - otherwise no more than 50% of the earth could be affected and the seas far less than the land due to the water shielding.
...9+6 months later toothing has lead to teething.
You'd be even more successful if you added trousers as well
As a European who's lived on both sides of the US-Canada fence I can definitely say that the grass is greener on this (the Canadian) side....at least when it's not buried under snow.
We don't even have a concrete bill of rights that can't be overriden in many regards by our legislature.
I would argue that this is what makes the Canadian system superior to the US system. If you look at the US system the only people who can get laws struck down as being "unconstitutional" are those who can afford exorbitant legal fees. Thus the laws which disadvantage or ideologically irritate the rich seem to be those that are most frequently challenged.
In Canada the government can override challenges for 5 years at a time. Thus at least the guy on the street has someone (in theory at any rate) that can effectively represent him/her. It certainly helps to prevent individual people or firms "forcing" their view point. It's not a perfect system but it is the best I've seen: a good compromise between an absolute constitution like the US and not having one at all like the UK.
On the other hand with that many degrees you have to wonder how much focus the guy has and whether he really has any interest in _doing_ research as opposed to learning about what other people have done.
Even if I buy that could you explain the new "missile defence" system then? Given the stellar success of the tests so far if anything its encouraging rogue states. Personally I think there is somewhat of a delusion in Washington that these things really work.
"stupid twit in washington DC"
No prizes for guessing the address of the individual that came top...
Sure we do - I always do my final C++ compile with the -O flag
Speaking as a European I don't see why any American would find this a strange concept given the outcome of your last election.
No, like the rest of us doctors are allowed to have a life when they are not working. My dad was a GP and would never dream of going to watch a film when he was on call. Not only is it disruptive to everyone else but you can't watch the film either if you are dealing with a call. Not only that but is the doctor's mind really going to be on the call or what is going on on the screen? As a patient I'd switch doctors if I found mine displaying such a gross lack of professionalism.
Now if we can just get that fusion reactor to work...
The solution to this is to teach kids not to run into the middle of the road. I was amazed at the ridiculously low speed limits around schools in the US. What happens when these kids grow up - they encounter traffic at real speeds and get killed?