Seth: Science is about discovery.New finding such as the earth is round, apparently, that's just in.New observations of black holes and investigations of perplex phenomenon, for example, how cats lap up milk, that sorts of thing, Eureka and all that. But we are interested today in what's gone missing in science. That's why have here the science classified want ads. This is Are We Alone. I'm Seth Shostak.
Molly: I'm Molly Bentley. Well, Seth, before we dive into the want ads you have there, figuring out what is missing in science is often a matter when you ask the question, because evidence that is missing is often discovered in time. For example, you know, fossil that shows the transition between reptiles and birds was missing for a long time. Scientists hadn't found it, but we now do have it.
Seth: Right! Eh, when Mendeleev invented the periodic table 150 years ago, there were some blank spots, for example, he was looking for an element that have the properties like silicon but heavier. It was missing, but not for long. Soon chemists found the Germanium, and it plugged the gap.
Molly: And Germanium was used in the first transistors, but these days they are made of Silicon, otherwise, our studio will be in the Germanium belly.
Seth: Right. And if we talk about this subject 50 years ago, we might have long form explanation why the east bulge of southern America fits so nicely into the coast line of Africa. The point is, the thing about science is that things that are known to be missing because a theory says it must exist are frequently and eventually found. And that’s because scientists go look for them since they know what they are looking for. Their tools get better and so forth.
Molly: OK, what's missing today? What do you have there on the paper? Seth, the science classifies.
Seth: Oh, let me see here. Oh, here is a good one. "Wanted: a cure for the cold". Well, Molly, you know it has to be somewhere, but scientists haven't found it.
Molly: That ads probably has been in classifies for a long time. How about something that's missing that is a little grander in scale? Anything like that?
Seth: Okay, let me look at the grander column. Here we go, "wanted: an explanation for 72% of the universe."
Molly: Wow, that's gone missing? 72% of the universe. What else it says there?
Seth: It's mysterious and blowing space apart. Cosmologies are in the dark about what it is. If found, call ... There is a number down here.
Molly: Call it! If there is a number call it. Let's find out more.
Seth: Okay!
Saul Perlmutter
Saul: Hello, this is Saul Perlmutter, at the University of California Berkley, and Lawrence Berkeley Laboratory.
Seth: Saul, this is Seth Shostak, with the science radio show - Are We Alone. Eh, you are cosmologist and I've read your ad. What is this stuff?
Saul: <laugh> Well, we've discovered that the universe is doing something a little bit unexpected. It's speeding up as it expands. So, it gets bigger and bigger and faster and faster. And, we suspect that there maybe an energy that we call dark energy. And it may make up 3/4 of all the stuff in the universe, but we don't know what it is and where it is.
Seth: Well, now wait a minute. Why do we think it is really there? I mean if it's missing, why do we need it to exist?
Saul: Well you need something that would power this amazing expansion of the universe to the point that it's going faster and faster as it expands. And one of the simplest ways perhaps to do it is if you can put an energy that prevails all of empty space.
Seth: Well what do we know is all about dark energy. It's something that is pushing the universe apart, it's causing the universe to blow up like a balloon. Do we know anything about what it is or its properties?
Saul: We have very little to go on so far. We know that it has a set of unusual properties that it has to have a sort of bouncing it to it, bringing it to it, and make the universe reproduce faster, so you get more and more universe, faster and faster. And that particular springiness, something we try to measure by going back and doing that same kind of measurement the history adventure of the universe was in much much more detail. And in the end, we hope that would begin to help us to differentiate the different possible explanations for what's going on.
Seth: Well, could you dare to guess what it might be? I mean maybe it's not a particle, not something you can put into a bottle and shack around, I mean it's just ...
Saul: No, I mean any ordinary stuff that we are used to, you know, touching, seeing... All those things are made out of materials that we know how springy they are. They are not very springy and in fact they will all make the universe slow down. So it has to be in a completely different category of substance and this is why it's such a surprise to the physics world that we have been doing very well accounting for everything we see with what they call the standard model of physics. You can break things down to many many definite places. And yet, it could be that the three quarter of the universe is in the form that we have not even included in the current study.
Seth: Okay. But Saul, is there any chance that this dark energy could all just be a mistake? I mean the claim that it exists depends on measuring an exploding star supernovae in galaxies far far away. Maybe the astronomers calibrated those exploding stars incorrectly, I mean, could dark energy just be a measurement error?
<...>
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ExamDiff
xdelta
Java xdelta
GNU Diff Utilities
WinMerge
xxdiff
KDiff3
CSDiff
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- java鐨勬暟緇勬槸瀵硅薄錛沜鐨勬暟緇勬槸鏁版嵁緇撴瀯銆?/li>
- java鐨勬暟緇勫０鏄庣殑鏃跺欎笉鑳藉寘鍚暟緇勭殑澶у皬錛屽彧鑳藉湪鏂板緩瀵硅薄鐨勬椂鍊欐寚瀹氭暟緇勫ぇ灝忥紱c鐨勬暟緇勫彲浠ュ湪澹版槑鐨勬椂鍊欏寘鍚暟緇勫ぇ灝忋?/li>
// java code
int array[10]; // illegal!!!
int array[] = new int[10]; // legal
// c code
int array[10]; // legal;
int array[10]; // illegal!!!
int array[] = new int[10]; // legal
// c code
int array[10]; // legal;
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- java鐨勬暟緇勫湪澹版槑鐨勬椂鍊欙紝[]鍙互鍦ㄥ彉閲忕殑宸﹁竟鎴栬呭彸杈癸紝鍙互絀烘牸涔熷彲浠ヤ笉絀烘牸錛沜鐨勬暟緇勫湪澹版槑鐨勬椂鍊橻]鍙兘鍦ㄥ彉閲忕殑鍙寵竟銆?/li>
// java code
int array[] = new int[3]; // legal;
int[] array = new int[3]; // legal;
int []array = new int[3]; // legal;
// c code
int [12] array; // illegal
int array[12]; // legal
int array [12]; // legal
int array[] = new int[3]; // legal;
int[] array = new int[3]; // legal;
int []array = new int[3]; // legal;
// c code
int [12] array; // illegal
int array[12]; // legal
int array [12]; // legal
涓嶆紜箣澶勮鎸囨槑錛岃阿璋€?br>
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int var = 1;
{
int var = 2;
{
int var = 3;
}
}
{
int var = 2;
{
int var = 3;
}
}
2. Rightmost value
int i, k=3, j=0;
i = (k++, j++); // after this, i==0, j==1, k==4
i = (k++, j++); // after this, i==0, j==1, k==4
3. Rightmost value in "while" block
while(i = foo(), i != 0){
}
}
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