Horizon, Host: Ted Simons

October 18, 2007


Host: Richard Ruelas

Quantum Physics


  • We talk to physicist Yakir Aharonov about the mysteries of quantum mechanics. Aharonov has come up with a way to measure on the quantum scale that involves using the past and the future in the present to make more accurate measurements.
Guests:
  • Alan Weisman - Alan Weisman, University of Arizona professor and author of “The World Without Us”
  • Yakir Aharanov - Physicist
Category: Science

View Transcript
>>Richard Ruelas:
Tonight on Horizon's special, first what would happen to the earth if humans disappeared? Then we'll go to the theory of quantum mechanics with one of the world's leading experts. All that next on horizon.

>> Announcer:
Horizon is made possible by contributions from the friends of eight, members of your Arizona PBS station. Thank you.

>> Richard Ruelas:
Good evening. I'm Richard Ruelas. Welcome to Horizon. What if every human were to suddenly disappear? How long would it take nature to recover? That's the question given a very detailed answer in the best-selling book "The World Without Us." it was written by University of Arizona journalism professor. We'll hear from him about his book. First here are some artist conceptions about what would happen to Manhattan after humans disappear.

>>Richard Ruelas:
"The world without humans" is number seven on the "New York Times"' hard cover nonfiction list. Christina Estes recently spoke to the author. Here is that interview.

>>Christina Estes:
Let's start by telling us why in the world you came one this idea, how you came one this idea, the world without us.

>>Alan Weisman:
Well, I'm a journalist. I cover the environment a lot. And these days most stories are environmental stories. I've been all over the world. And I've looked for a way to write something that would talk about all these different things that are going on in the world and how they are connected. And you do it in such a way that readers wouldn't be repelled, that the book wouldn't be so overwhelming or frightening or depressing that they just wouldn't want to spend time with it. And an editor of the magazine pointed out to me that I had once written a piece for Harper's at Chernobyl about the villages around the reactor that once the villages were evacuated, nature took over the walls and tree roots and sidewalks. He said, what would happen if that happened everywhere? And I realized what an interesting question. And just suppose humans fled. I mean, not a radioactive disaster. But just suppose we were gone. Say some Homo-Sapien violence picked us up. A lot of people believe in the rapture. Suppose we were just gone. Instead of readers reading something, oh, lord, we're going to die if this keeps going on. We're already dead. And yet because of my research they get to see what happens next. And it kind of disarms the fear factor and gives us an irresistible glimpses of the future that's always so fascinating. So I went around the world and I met lots of authorities, scientists and eyewitnesses and I found some very interesting things.

>>Christina Estes:
A lot of very interesting things. Let's touch on this as much as we possibly can. Start with the Korean DMZ trip. Tell us about that.

>>Alan Weisman:
That was one of the first trips I made for this book. You have a two and a half mile wide strip that bisects the whole Korean peninsula. It's been devoid of humans since 1953 when the truce was signed. You have two of the most hostile armies facing each other one on each side of each other. That strip has reverted to wilderness. It was once villages and rice pad dis. Today some of the most precious endangered species in all of Asia live there. You got go there and two are miss on each side of each other. Amidst all this bristling arm amounts comes floating in these credible birds. The red crane next to the whooping crane, rarest thing I know. They settle in there, winter in the Korean DMZ. It's an incredible metaphor that this tension, human tension where we have fled into no one's land in between becomes the refuge for species.

>>Christina Estes:
We showed some photos, the photo montage of Manhattan and what that would look like without humans. Talk a little bit about that and what you discovered. First, the subways.

>>Alan Weisman:
Yeah. Manhattan, the word derives from an ancient Algonquin term that means hilly. There used to be lots of hills before they were smashed down to superimpose a city on it. All the rivers and streams between those hills went underground. So the subway engineers have to pump about 13 million gallons, even on a sunny day, 13 million gallons of water to the ocean. Now, if they weren't there maintaining the 800 pumps down there, or if nobody was in the power plants, well, the subways would flood within two or three days and all those columns that hold up the streets would start to rust and eventually they'd corrode and collapse and within two decades the streets would be crumbling above them and we'd have rivers in Manhattan on the service. In the meantime pipes would be freezing in building because there would be no heat. Plants could be colonizing. You'd have plastic bags clogging up the sewers. No one would be raking away the leaves that set in the gutters. They'd be germinating, coming up through the sidewalks that no one would be patching. Everyone I talked to from civil engineers to maintenance personnel to the biologists and botanists in botanical garden agreed that New York would revert to a forest again.

>>Christina Estes:
What about cockroaches or rats, the things we'd like to be rid of. What would happen here?

>>Alan Weisman:
In a northern city like New York cockroaches are seeking heat in the wintertime. They go into buildings. When the heat's off cockroaches won't survive the winter. So those cities aren't going to have to worry about cockroaches. You come further south, desert, tropics, cockroach will be back in its element. Sorry.

>>Christina Estes:
Cockroaches stay in Arizona whether we're here or not, huh?

>>Alan Weisman:
Right. And as for rats, a lot of the rats that are in urban areas are imported rats, Norway rats; they came over in ships on colonial times. They established themselves. They haven't done that well out in the countryside. We have wood rats out in the country. Probably those urban rats will become food for all sorts of raptors, like falcons and hawks and other wild live that will come pouring into cities when humans are no longer occupying them.

>>Christina Estes:
And what were you able to find when it comes to modern-day buildings versus some of the very old buildings? I know you've seen a pretty recent example with the sea side resort in Cyprus. What does that tell you?

>>Alan Weisman:
Turns out the oldest buildings we built will probably last the longest. In New York City St. Paul's chapel is the oldest building right across from the world trade center. Made out of Manhattan sift which the island is made out of. It was not even budged by the planes. It will probably be -- that and some old stone buildings will probably be the oldest standing in New York. The resort you're referring to was a sea side resort on the east side of cypress that was built by oil money. Then it got built on the Turkish side during the civil war. The Turks put a barbed wire fence around it thinking this would be a great bargaining chip when they got back together for reunification talks. Nature has just rushed back. In sand dunes filled the hotel lob business. Animals colonized the rooms now. There are ornamental plants growing right through the roofs. The streets are now fields of wild flowers and bathers on the beaches are all sea turtles. The buildings are no longer salvageable.

>>Christina Estes:
Let's talk about one really big chapter dealing with plastic. Because when you describe all the flowers and the trees, it sounds so lovely. But there's a lot of ugliness out there in terms of what will be left behind if humans were to cease to exist. I know there's a nice name for it but you refer to it as the floating garbage pit. Talk about that.

>>Alan Weisman:
Well, you know, one of the plastics experts that I spoke to told me that -- since you mentioned trees, it took a long take for microbes to evolve to eat the lignin in the trunks of the first trees. Those trees would fall over, get covered over until they would get depressed, coal-bearing layer today. New material on the block entered the 20th century, entered the mainstream in the years after World War II. Now it's Omni present, a lot of it turns out to be in the ocean. Just like everything washes to sea eventually, entire mountain ranges will erode and go to sea, plastic being a lot wetter than rocks is getting there a lot faster. It's going down storm drains and into streams or blowing on the wind. And this garbage patch is the size of a small continent. It's in between Hawaii and California, there's another one in the Indian Ocean. And the mass of plastic on the surface is about six times that of plankton now. It's rather remarkable. Plus wave action does the same thing to plastic as it does to rocks, turns them into little grains of sand. We get beaches. We have smaller and smaller particle nothing can really eat it but stuff swallows it. Smaller and smaller organisms are finding little pieces of plastic that they mistake for like a fish egg or something organic and they're eating it. And we find sea birds now dead with over four pounds of plastic in them. And so imagine this going all the way down the food chain because even zoe plankton, which plankton forms the basis of our food chain are eating plastic. And this is a new discovery that we don't even know what it means yet.

>>Christina Estes:
And you also found it's not just a matter of a plastic bag blowing into the ocean or those six-pack rings but actual products, a lot of beauty aids, have plastic in there. So if I'm washing my face and it's going down the drain --

>>Alan Weisman:
I was actually staggered to find out that this is not a case of unintentional consequences. Intentionally many manufacturers and people can just look at the bottles that they have in their bathrooms, many manufacturers of facial cleansers with little exfoliates in it? Is some of the good ones are made out of cot seeds or jojoba seeds? But a lot of them are made out of polyester. We are intentionally flushing it into the oceans where organisms are discovering it and mistaking it for food.

>>Christina Estes:
What do you want people to take away from your book? Did you have a mission or goal when you started?

>>Alan Weisman:
Well, you know, I didn't write "The World Without Us" because I think that human beings don't belong on this planet. Obviously we do. We evolved to get to this point the same as any other species and I think we deserve to be here. But I think we have grown so huge in our impact in our reach, in our ability to harvest, in our sheer numbers that we have to bring ourselves into better balance with nature.

>>Christina Estes:
Thank you so much.

>>Alan Weisman:
It's been a pleasure. Thank you, Christine.

>>Richard Ruelas:
The world of quantum mechanics may be -- thanks to physicist Yakir Aharanov. He found a way to measure on the quantum scale that measures two measurements, one in the past and one in the future. Horizon's Mike Sauceda spoke to him recently.

>>Mike Sauceda:
Dr. Aharanov, thanks for appearing on Horizon.

>>Yakir Aharanov:
Thanks for inviting me.

>>Mike Sauceda:
Give us a brief description of what quantum mechanics is.

>>Yakir Aharanov:
Well, the reason for the name, it was discovered that if you look at any form of energy, for example light waves, it was discovered that they are made of little lunches of energy -- lumps of energy that can not be divided further. This is why they are called quantum, meaning that you can't difficult it. That's a very important thing. Because if indeed any form that we interact with, a system that we observe involves a minimum amount of energy that you cannot reduce more, that means you cannot disturb it. So contrary to classical physics where people -- physics where people hope you can study it without learning -- and learn what it is, we discovered that very small systems, you're observing it and disturbing it so much that you can't understand what it was before. The whole idea about quantum mechanics is you cannot predict the future. Anytime you try to measure things enough in order to predict the future would fail. Quantum physics teaches us that nature is not deterministic. It cannot tell you what the future is. That means that quantum mechanics seems to indicate nature is capricious. Two things completely the same at one time behave differently at another time. In other words, two items. One of them will decay after one minute and one after an hour. There was no difference between them. So it looks like very strange. Why should two things that are the same, why should they behave differently? Einstein was one of the inventors for the mechanics was very unhappy about it. He said he doesn't believe that God throws dice in order to decide when earth will decay. It didn't make sense to him. The whole point of my work is really to find out why does God play dice. Namely, what does nature gain from this particular capriciousness.

>>Mike Sauceda:
was there a time when scientists tried to use the laws of motion to describe the microscopic world?

>>Yakir Aharanov:
There was time when they tried to do it and then they found it was inconsistent. For example, if you look, once it was discovered that atom is made out of a proton in the center with positive charges and electrons moving around it, then they discovered immediately that if the laws of classical physics were correct the atom will have to completely decay. Because the atoms going around the proton would have to emit energy and then they would fall to the center. So we would completely collapse immediately if we were governed by the laws of classical physics. It's only quantum mechanics that can explain why atoms are stable. Atoms are stable. That's the fundamental thing.

>>Mike Sauceda:
Is our world ruled by quantum mechanics even though we don't realize it?

>>Yakir Aharanov:
Yes. But quantum mechanics also teaches us that if you have a large collection of quantum particles, the whole collection together, billions and billions and billions of atoms, the collective behavior of this behaves like a classical physics. Like insurance companies, they can't predict when a particular person will be sick. But they have enough people they know how many of them will get sick one time and how many another, that's how they make their profit. Because they predict -- they can predict what happens with large numbers of particles, people, even though they don't know what each individual one will do. That's how quantum mechanics explains the classical behavior.

>>Mike Sauceda:
So it's about probability.

>>Yakir Aharanov:
Yeah. It's about the collective behavior, lots and lots of things you can't predict each one of them exactly but you can predict what the check of them will do.

>>Mike Sauceda:
Are there certain states of matter that have been created, exotic matter like the bull's eye Einstein state?

>>Yakir Aharanov:
Yes. It turns out very recently you can compare a large number of atoms identically. If you have two particles exactly the same they behave in a very interesting way. There are two different kinds of particles that are the same, those of [indiscernible] and those together they like to be all in the same state. That's how you get a large number of them to behave in a very stable way. This is a very important discovery recently people got Nobel prizes for working on that subject.

>>Mike Sauceda:
You have written a book "Quantum Paradoxes" if in that book you outline some of your work. Part of your work is to be able to measure at the quantum level, be able to learn something, be able to determine maybe how the dice roll?

>>Yakir Aharanov:
Yeah. Well, there are two things I have to say about it. The first thing that I discovered was the following, that's the most important thing. That if we say that two atoms that are the same behave differently, I ask myself why do they behave differently? Maybe they're trying to tell us - nature is trying to tell us if we later look and find they are different there was some difference already before but we could not discover it honestly right to the time when we look at it again. So I then decided that I should formulate physics in a way that controls the past and the future of the elemental present. Because in the future we find some more information. Then I started to investigate, how do I look to find out the properties of these two ways of looking at systems. And I discovered that only way to look at it is to do what they call weak measurements. Take measurements that are specifically designed in such a way they would not disturb the system. You don't have to look at many of them before you collect the information. But with this new way of looking at quantum systems I can find this new beautiful reality that is described by most information coming from the past and coming back from the future like in the movie coming back from the future, seeing the future come back and describe -- to give more information about the system in the present.

>>Mike Sauceda:
So in a way are you starting with the end result? The measurement that you --

>>Yakir Aharanov:
Yeah. I am saying that the true measurement you find in the present. One measurement that was done before. Like in organizing we have to measure it. But also another measurement would be done after we look at the present. And this extra measurement will tell us more information about what we saw in the present. So the future is also element for the present. That's a new approach to time that quantum mechanics is teaching us. And I say this is that so why does god play dice. What does nature gain from capriciousness? It's not capriciousness anymore because you have two items that look the same in the past but they are going to be different in the future. The -- even though we find it only later. So it's a new approach to time. The future is just as important for the present as the past. And that is really a revolutionary thing. Because we have to learn to rethink about everything if we say that it is important for our decision. It would have bearing of free will, bearing of understanding what time is. That's why I am so excited about this development.

>>Mike Sauceda:
Get to the question of causality. Does the future affect the past.

>>Yakir Aharanov:
That is the point. You say the future has leverage now, I will come and decide to do something else. But in quantum mechanics because of room to find inside it new order. That if you don't do the right thing you will not see it. It will look to you like completely noise. But if you do the right thing in the future, come back, then out of this noise, quantum noise, comes new kind of structure. This is what we are investigating.

>>Mike Sauceda:
So you've been able to look into the quantum world, which we haven't been able to do. What have you seen?

>>Yakir Aharanov:
Well, I've seen a beautiful world. I'm just learning to see. I have seen that for example particles that usually are -- they have one charge they result as a different charge, negative charge. All kinds of things. If you begin to look at it directly you find the quantum world is very, very rich. We are just beginning to see how rich it is. Hopefully eventually when we understand it and what people are doing in the world in many laboratories now experimenting, investigating what they call weak phenomena. Once you learn to do it I'm sure it will have gross implications for philosophy of physics, for understanding of physics but also technical application. But that's too early to say yet what will come out of it.

>>Mike Sauceda:
Is it possible that we might learn whether there really is a reality there or whether we are affecting reality by observing it?

>>Yakir Aharanov:
That's the whole point. The whole point is there was reality of the time. But because we looked at it, you know, it's like -- think about biological cells. There are two-ways to look at biological cells. One is you look and you kill them and one is experiment to do [indiscernible] if you look very carefully you can see how they behave with biological cells. If you look carefully you don't kill it you see a different behavior. I have learned to look at quantum mechanics by not killing it, by doing a very weak type of disturbance of a new kind I find what it is related to. People found there was no reality and found there is a reality there. Very rich.

>>Mike Sauceda:
You can observe the momentum and the location of the particle?

>Yakir Aharanov:
I can observe it, yes, because during the time doing it in the past I measured the position. And in the future I measured the momentum. And from most information I can say about the present that I had most information. In the past alone you could not do it. People only looked up to now what could be done just by experiments in the past. But by combining experiments in the past and experiments in the future I can indicate -- I can indicate position.

>>Mike Sauceda:
What do you hope to learn, think you might learn from your new way of measurement? Is that something that's hard to tell?

>>Yakir Aharanov:
I'm going to learn how beautiful the world is. I'm just beginning to tip this new reality. It is very exciting. So we are to find new things in the quantum system that were missed before.

>>Mike Sauceda:
Are scientists getting closer to marrying quantum mechanics with relativity theory?

>>Yakir Aharanov:
Some people hope so. Some don't think so. So the idea is that you describe quantum particle not as a point particle but as a little string. And that's why the theory called string theory. The string theory mathematically is extremely interesting. And it shows a promise to overcome the difficulties of marrying quantum mechanics and relativity. But many people, including me, still believe that it's not a theory. A beautiful mathematical development but it's not really a satisfactory theory. So it's not really going to be the right answer. I think the right answer, my own point of view, will come from the better understanding of quantum mechanics. And once you better understand it you will be able to do the correct joining of two theories.

>>Mike Sauceda:
Dr. Hannah, thank you for joining us. It's been a pleasure.

>>Yakir Aharanov:
A pleasure Mike, too. And thank you for inviting me.

>>Richard Ruelas:
Thank you for joining us on this Horizon science special. I'm Richard Ruelas has. Have a good night.

The World Without Us


  • What would the world be like without humans? University of Arizona journalism professor Alan Weisman has taken on that question in his new book The World Without Us. Hear from the author as he appears on HORIZON.
Guests:
  • Alan Weisman - Alan Weisman, University of Arizona professor and author of “The World Without Us”
  • Yakir Aharanov - Physicist
Category: Environment

View Transcript
>>Richard Ruelas:
Tonight on Horizon's special, first what would happen to the earth if humans disappeared? Then we'll go to the theory of quantum mechanics with one of the world's leading experts. All that next on horizon.

>> Announcer:
Horizon is made possible by contributions from the friends of eight, members of your Arizona PBS station. Thank you.

>> Richard Ruelas:
Good evening. I'm Richard Ruelas. Welcome to Horizon. What if every human were to suddenly disappear? How long would it take nature to recover? That's the question given a very detailed answer in the best-selling book "The World Without Us." it was written by University of Arizona journalism professor. We'll hear from him about his book. First here are some artist conceptions about what would happen to Manhattan after humans disappear.

>>Richard Ruelas:
"The world without humans" is number seven on the "New York Times"' hard cover nonfiction list. Christina Estes recently spoke to the author. Here is that interview.

>>Christina Estes:
Let's start by telling us why in the world you came one this idea, how you came one this idea, the world without us.

>>Alan Weisman:
Well, I'm a journalist. I cover the environment a lot. And these days most stories are environmental stories. I've been all over the world. And I've looked for a way to write something that would talk about all these different things that are going on in the world and how they are connected. And you do it in such a way that readers wouldn't be repelled, that the book wouldn't be so overwhelming or frightening or depressing that they just wouldn't want to spend time with it. And an editor of the magazine pointed out to me that I had once written a piece for Harper's at Chernobyl about the villages around the reactor that once the villages were evacuated, nature took over the walls and tree roots and sidewalks. He said, what would happen if that happened everywhere? And I realized what an interesting question. And just suppose humans fled. I mean, not a radioactive disaster. But just suppose we were gone. Say some Homo-Sapien violence picked us up. A lot of people believe in the rapture. Suppose we were just gone. Instead of readers reading something, oh, lord, we're going to die if this keeps going on. We're already dead. And yet because of my research they get to see what happens next. And it kind of disarms the fear factor and gives us an irresistible glimpses of the future that's always so fascinating. So I went around the world and I met lots of authorities, scientists and eyewitnesses and I found some very interesting things.

>>Christina Estes:
A lot of very interesting things. Let's touch on this as much as we possibly can. Start with the Korean DMZ trip. Tell us about that.

>>Alan Weisman:
That was one of the first trips I made for this book. You have a two and a half mile wide strip that bisects the whole Korean peninsula. It's been devoid of humans since 1953 when the truce was signed. You have two of the most hostile armies facing each other one on each side of each other. That strip has reverted to wilderness. It was once villages and rice pad dis. Today some of the most precious endangered species in all of Asia live there. You got go there and two are miss on each side of each other. Amidst all this bristling arm amounts comes floating in these credible birds. The red crane next to the whooping crane, rarest thing I know. They settle in there, winter in the Korean DMZ. It's an incredible metaphor that this tension, human tension where we have fled into no one's land in between becomes the refuge for species.

>>Christina Estes:
We showed some photos, the photo montage of Manhattan and what that would look like without humans. Talk a little bit about that and what you discovered. First, the subways.

>>Alan Weisman:
Yeah. Manhattan, the word derives from an ancient Algonquin term that means hilly. There used to be lots of hills before they were smashed down to superimpose a city on it. All the rivers and streams between those hills went underground. So the subway engineers have to pump about 13 million gallons, even on a sunny day, 13 million gallons of water to the ocean. Now, if they weren't there maintaining the 800 pumps down there, or if nobody was in the power plants, well, the subways would flood within two or three days and all those columns that hold up the streets would start to rust and eventually they'd corrode and collapse and within two decades the streets would be crumbling above them and we'd have rivers in Manhattan on the service. In the meantime pipes would be freezing in building because there would be no heat. Plants could be colonizing. You'd have plastic bags clogging up the sewers. No one would be raking away the leaves that set in the gutters. They'd be germinating, coming up through the sidewalks that no one would be patching. Everyone I talked to from civil engineers to maintenance personnel to the biologists and botanists in botanical garden agreed that New York would revert to a forest again.

>>Christina Estes:
What about cockroaches or rats, the things we'd like to be rid of. What would happen here?

>>Alan Weisman:
In a northern city like New York cockroaches are seeking heat in the wintertime. They go into buildings. When the heat's off cockroaches won't survive the winter. So those cities aren't going to have to worry about cockroaches. You come further south, desert, tropics, cockroach will be back in its element. Sorry.

>>Christina Estes:
Cockroaches stay in Arizona whether we're here or not, huh?

>>Alan Weisman:
Right. And as for rats, a lot of the rats that are in urban areas are imported rats, Norway rats; they came over in ships on colonial times. They established themselves. They haven't done that well out in the countryside. We have wood rats out in the country. Probably those urban rats will become food for all sorts of raptors, like falcons and hawks and other wild live that will come pouring into cities when humans are no longer occupying them.

>>Christina Estes:
And what were you able to find when it comes to modern-day buildings versus some of the very old buildings? I know you've seen a pretty recent example with the sea side resort in Cyprus. What does that tell you?

>>Alan Weisman:
Turns out the oldest buildings we built will probably last the longest. In New York City St. Paul's chapel is the oldest building right across from the world trade center. Made out of Manhattan sift which the island is made out of. It was not even budged by the planes. It will probably be -- that and some old stone buildings will probably be the oldest standing in New York. The resort you're referring to was a sea side resort on the east side of cypress that was built by oil money. Then it got built on the Turkish side during the civil war. The Turks put a barbed wire fence around it thinking this would be a great bargaining chip when they got back together for reunification talks. Nature has just rushed back. In sand dunes filled the hotel lob business. Animals colonized the rooms now. There are ornamental plants growing right through the roofs. The streets are now fields of wild flowers and bathers on the beaches are all sea turtles. The buildings are no longer salvageable.

>>Christina Estes:
Let's talk about one really big chapter dealing with plastic. Because when you describe all the flowers and the trees, it sounds so lovely. But there's a lot of ugliness out there in terms of what will be left behind if humans were to cease to exist. I know there's a nice name for it but you refer to it as the floating garbage pit. Talk about that.

>>Alan Weisman:
Well, you know, one of the plastics experts that I spoke to told me that -- since you mentioned trees, it took a long take for microbes to evolve to eat the lignin in the trunks of the first trees. Those trees would fall over, get covered over until they would get depressed, coal-bearing layer today. New material on the block entered the 20th century, entered the mainstream in the years after World War II. Now it's Omni present, a lot of it turns out to be in the ocean. Just like everything washes to sea eventually, entire mountain ranges will erode and go to sea, plastic being a lot wetter than rocks is getting there a lot faster. It's going down storm drains and into streams or blowing on the wind. And this garbage patch is the size of a small continent. It's in between Hawaii and California, there's another one in the Indian Ocean. And the mass of plastic on the surface is about six times that of plankton now. It's rather remarkable. Plus wave action does the same thing to plastic as it does to rocks, turns them into little grains of sand. We get beaches. We have smaller and smaller particle nothing can really eat it but stuff swallows it. Smaller and smaller organisms are finding little pieces of plastic that they mistake for like a fish egg or something organic and they're eating it. And we find sea birds now dead with over four pounds of plastic in them. And so imagine this going all the way down the food chain because even zoe plankton, which plankton forms the basis of our food chain are eating plastic. And this is a new discovery that we don't even know what it means yet.

>>Christina Estes:
And you also found it's not just a matter of a plastic bag blowing into the ocean or those six-pack rings but actual products, a lot of beauty aids, have plastic in there. So if I'm washing my face and it's going down the drain --

>>Alan Weisman:
I was actually staggered to find out that this is not a case of unintentional consequences. Intentionally many manufacturers and people can just look at the bottles that they have in their bathrooms, many manufacturers of facial cleansers with little exfoliates in it? Is some of the good ones are made out of cot seeds or jojoba seeds? But a lot of them are made out of polyester. We are intentionally flushing it into the oceans where organisms are discovering it and mistaking it for food.

>>Christina Estes:
What do you want people to take away from your book? Did you have a mission or goal when you started?

>>Alan Weisman:
Well, you know, I didn't write "The World Without Us" because I think that human beings don't belong on this planet. Obviously we do. We evolved to get to this point the same as any other species and I think we deserve to be here. But I think we have grown so huge in our impact in our reach, in our ability to harvest, in our sheer numbers that we have to bring ourselves into better balance with nature.

>>Christina Estes:
Thank you so much.

>>Alan Weisman:
It's been a pleasure. Thank you, Christine.

>>Richard Ruelas:
The world of quantum mechanics may be -- thanks to physicist Yakir Aharanov. He found a way to measure on the quantum scale that measures two measurements, one in the past and one in the future. Horizon's Mike Sauceda spoke to him recently.

>>Mike Sauceda:
Dr. Aharanov, thanks for appearing on Horizon.

>>Yakir Aharanov:
Thanks for inviting me.

>>Mike Sauceda:
Give us a brief description of what quantum mechanics is.

>>Yakir Aharanov:
Well, the reason for the name, it was discovered that if you look at any form of energy, for example light waves, it was discovered that they are made of little lunches of energy -- lumps of energy that can not be divided further. This is why they are called quantum, meaning that you can't difficult it. That's a very important thing. Because if indeed any form that we interact with, a system that we observe involves a minimum amount of energy that you cannot reduce more, that means you cannot disturb it. So contrary to classical physics where people -- physics where people hope you can study it without learning -- and learn what it is, we discovered that very small systems, you're observing it and disturbing it so much that you can't understand what it was before. The whole idea about quantum mechanics is you cannot predict the future. Anytime you try to measure things enough in order to predict the future would fail. Quantum physics teaches us that nature is not deterministic. It cannot tell you what the future is. That means that quantum mechanics seems to indicate nature is capricious. Two things completely the same at one time behave differently at another time. In other words, two items. One of them will decay after one minute and one after an hour. There was no difference between them. So it looks like very strange. Why should two things that are the same, why should they behave differently? Einstein was one of the inventors for the mechanics was very unhappy about it. He said he doesn't believe that God throws dice in order to decide when earth will decay. It didn't make sense to him. The whole point of my work is really to find out why does God play dice. Namely, what does nature gain from this particular capriciousness.

>>Mike Sauceda:
was there a time when scientists tried to use the laws of motion to describe the microscopic world?

>>Yakir Aharanov:
There was time when they tried to do it and then they found it was inconsistent. For example, if you look, once it was discovered that atom is made out of a proton in the center with positive charges and electrons moving around it, then they discovered immediately that if the laws of classical physics were correct the atom will have to completely decay. Because the atoms going around the proton would have to emit energy and then they would fall to the center. So we would completely collapse immediately if we were governed by the laws of classical physics. It's only quantum mechanics that can explain why atoms are stable. Atoms are stable. That's the fundamental thing.

>>Mike Sauceda:
Is our world ruled by quantum mechanics even though we don't realize it?

>>Yakir Aharanov:
Yes. But quantum mechanics also teaches us that if you have a large collection of quantum particles, the whole collection together, billions and billions and billions of atoms, the collective behavior of this behaves like a classical physics. Like insurance companies, they can't predict when a particular person will be sick. But they have enough people they know how many of them will get sick one time and how many another, that's how they make their profit. Because they predict -- they can predict what happens with large numbers of particles, people, even though they don't know what each individual one will do. That's how quantum mechanics explains the classical behavior.

>>Mike Sauceda:
So it's about probability.

>>Yakir Aharanov:
Yeah. It's about the collective behavior, lots and lots of things you can't predict each one of them exactly but you can predict what the check of them will do.

>>Mike Sauceda:
Are there certain states of matter that have been created, exotic matter like the bull's eye Einstein state?

>>Yakir Aharanov:
Yes. It turns out very recently you can compare a large number of atoms identically. If you have two particles exactly the same they behave in a very interesting way. There are two different kinds of particles that are the same, those of [indiscernible] and those together they like to be all in the same state. That's how you get a large number of them to behave in a very stable way. This is a very important discovery recently people got Nobel prizes for working on that subject.

>>Mike Sauceda:
You have written a book "Quantum Paradoxes" if in that book you outline some of your work. Part of your work is to be able to measure at the quantum level, be able to learn something, be able to determine maybe how the dice roll?

>>Yakir Aharanov:
Yeah. Well, there are two things I have to say about it. The first thing that I discovered was the following, that's the most important thing. That if we say that two atoms that are the same behave differently, I ask myself why do they behave differently? Maybe they're trying to tell us - nature is trying to tell us if we later look and find they are different there was some difference already before but we could not discover it honestly right to the time when we look at it again. So I then decided that I should formulate physics in a way that controls the past and the future of the elemental present. Because in the future we find some more information. Then I started to investigate, how do I look to find out the properties of these two ways of looking at systems. And I discovered that only way to look at it is to do what they call weak measurements. Take measurements that are specifically designed in such a way they would not disturb the system. You don't have to look at many of them before you collect the information. But with this new way of looking at quantum systems I can find this new beautiful reality that is described by most information coming from the past and coming back from the future like in the movie coming back from the future, seeing the future come back and describe -- to give more information about the system in the present.

>>Mike Sauceda:
So in a way are you starting with the end result? The measurement that you --

>>Yakir Aharanov:
Yeah. I am saying that the true measurement you find in the present. One measurement that was done before. Like in organizing we have to measure it. But also another measurement would be done after we look at the present. And this extra measurement will tell us more information about what we saw in the present. So the future is also element for the present. That's a new approach to time that quantum mechanics is teaching us. And I say this is that so why does god play dice. What does nature gain from capriciousness? It's not capriciousness anymore because you have two items that look the same in the past but they are going to be different in the future. The -- even though we find it only later. So it's a new approach to time. The future is just as important for the present as the past. And that is really a revolutionary thing. Because we have to learn to rethink about everything if we say that it is important for our decision. It would have bearing of free will, bearing of understanding what time is. That's why I am so excited about this development.

>>Mike Sauceda:
Get to the question of causality. Does the future affect the past.

>>Yakir Aharanov:
That is the point. You say the future has leverage now, I will come and decide to do something else. But in quantum mechanics because of room to find inside it new order. That if you don't do the right thing you will not see it. It will look to you like completely noise. But if you do the right thing in the future, come back, then out of this noise, quantum noise, comes new kind of structure. This is what we are investigating.

>>Mike Sauceda:
So you've been able to look into the quantum world, which we haven't been able to do. What have you seen?

>>Yakir Aharanov:
Well, I've seen a beautiful world. I'm just learning to see. I have seen that for example particles that usually are -- they have one charge they result as a different charge, negative charge. All kinds of things. If you begin to look at it directly you find the quantum world is very, very rich. We are just beginning to see how rich it is. Hopefully eventually when we understand it and what people are doing in the world in many laboratories now experimenting, investigating what they call weak phenomena. Once you learn to do it I'm sure it will have gross implications for philosophy of physics, for understanding of physics but also technical application. But that's too early to say yet what will come out of it.

>>Mike Sauceda:
Is it possible that we might learn whether there really is a reality there or whether we are affecting reality by observing it?

>>Yakir Aharanov:
That's the whole point. The whole point is there was reality of the time. But because we looked at it, you know, it's like -- think about biological cells. There are two-ways to look at biological cells. One is you look and you kill them and one is experiment to do [indiscernible] if you look very carefully you can see how they behave with biological cells. If you look carefully you don't kill it you see a different behavior. I have learned to look at quantum mechanics by not killing it, by doing a very weak type of disturbance of a new kind I find what it is related to. People found there was no reality and found there is a reality there. Very rich.

>>Mike Sauceda:
You can observe the momentum and the location of the particle?

>Yakir Aharanov:
I can observe it, yes, because during the time doing it in the past I measured the position. And in the future I measured the momentum. And from most information I can say about the present that I had most information. In the past alone you could not do it. People only looked up to now what could be done just by experiments in the past. But by combining experiments in the past and experiments in the future I can indicate -- I can indicate position.

>>Mike Sauceda:
What do you hope to learn, think you might learn from your new way of measurement? Is that something that's hard to tell?

>>Yakir Aharanov:
I'm going to learn how beautiful the world is. I'm just beginning to tip this new reality. It is very exciting. So we are to find new things in the quantum system that were missed before.

>>Mike Sauceda:
Are scientists getting closer to marrying quantum mechanics with relativity theory?

>>Yakir Aharanov:
Some people hope so. Some don't think so. So the idea is that you describe quantum particle not as a point particle but as a little string. And that's why the theory called string theory. The string theory mathematically is extremely interesting. And it shows a promise to overcome the difficulties of marrying quantum mechanics and relativity. But many people, including me, still believe that it's not a theory. A beautiful mathematical development but it's not really a satisfactory theory. So it's not really going to be the right answer. I think the right answer, my own point of view, will come from the better understanding of quantum mechanics. And once you better understand it you will be able to do the correct joining of two theories.

>>Mike Sauceda:
Dr. Hannah, thank you for joining us. It's been a pleasure.

>>Yakir Aharanov:
A pleasure Mike, too. And thank you for inviting me.

>>Richard Ruelas:
Thank you for joining us on this Horizon science special. I'm Richard Ruelas has. Have a good night.

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