lucaspa

Can someone explain NS (in detail) to me? From what I read it seems to be missing a specific explaination...that being design. Is there a simulation that can explain how NS changes an organism over-time in relationship to enviroment/etc. To me as it stands, I gather that it "choses" a design (kinda) rather then naturally evolving, and that's frustrating.

Better to read Dennett. Natural selection is an unintelligent process to give design. It is an algorithm to get design. That is, follow the steps and design is a guaranteed outcome.

So, yes, plants and animals are designed. But designed by natural selection.

oh ok! In that case I guess I meant more of the biological mutations that cause a specific entity to produce...skin, feathers, teeth, etc. When it comes to those components what concludes which part is suitable for what enviroment and how? Is it just a random outcome from NS? For example, teeth: were there cases that didnt use the composition that makes up the teeth, animals or such that died off because it wasn't advantagous for that composition?

Yes. The competition for scarce resources is what "concludes" that a trait is suitable for that environment.

Look at natural selection as a design competition. The environment sets the design problem. Such as: what design will allow a water predator to move thru water fast enough to catch and eat prey?

Each individual is a possible design for that problem. BUT, there are far more design entries than the environment can support. So the individuals/designs have to compete for the scarce resources: in this case, prey. Those designs that are better win and those designs that are worse lose.

Now, the key is that the winners reproduce and their offspring inherit their designs. But the offspring also modifiy the designs due to variation. So now you have a competition between the modified design in the next generation. Again, not every design can win. The better designs win and the poorer designs lose.

And so it goes generation after generation after generation. An accumulation of design modifications.

In the example I gave above, physics and the necessity to bite and hold prey means that there is one general design for a water-borne predator. This is why sharks, ichthyosaurs, and dolphins look very similar. BUT, the particular starting point of design (land animal for dolphins) and chance in the types of variations thrown up, means that there are differences. For instance, since dolphins have a modified running motion for swimming (since they started out as runners), their tail fin is horizontal. And dolphins born with a tail fin not horizontal would not go as fast as those born with a horizontal tail fin.

I am trying to make sense that everything that has evolved to this point can be seen in terms of single interactions with it's enviroment. I wasn't sure if that was implied or not. I could see how the process works in my mind, it just didn't seem to work the way it was explained. I guess I wanted to know more about macro/micro mutation, not NS.

1. There is not a SINGLE interaction with the environment. There are multiple and simultaneous interactions. We tend to look at the few simple interactions because they are easier to understand. But most of the time there are contradictory interactions and natural selection must find the best compromise design. Also, there is always a cost-benefit analysis.

2. What do you think is "micro" and "macro" mutation? Some mutations are in Hox developmental genes and can have a huge effect. For instance, change one base in the Ubx gene and you go from multiple legs to six legs or the reverse. Or change the Manx gene and either get or lose a complete tail. But whether such radical changes between two generations happen during evolution is doubtful.

So as of now I'm predicting it's gonna have a positive effect on public's interest in fundamental physics and a positive effect on the scientific community---and will be especially good for physics (if it has any measurable effect at all.)

 

but this is a GUESS and other people are welcome to disagree and shake heads and say book will have a negative effect.

I'm one of those that disagree. I'm afraid the effect will be negative. People don't understand that controversy like Smolin is stirring up is common in science. They will just look at this as another reason to think science is unreliable and scientists don't know what they are talking about. I wish Smolin and Woit had confined their efforts to forums restricted to the physics community instead of going to the general public

I'd like to be wrong.

^ but the majority of this book's audience work in, study in, or are deeply interested in (the guys who fund things) physics. The average layperson hasn't even heard of string theory, and the ones who have read books like the elegant univers in order to better familiarize themselveswith it. This book's target audience is to people working in or studying physics, and is so aimed to raise awareness in the physics community that string theory is not all its cracked up to be, and that alternatives exist.

Let's test this. If the book were targeted to the physics community, it would have a lot of mathematics in it. But it doesn't; instead the reviews all comment on the personal touch and how Smolin weaves his personal life into it. Such a style is designed to reach a non-physics audience. If the real discussion is the state of physics and string theory, then physicists don't need Smolin's life story and anecdotes, do they?

Besides, the physics community isn't large enough to put the book in the Bestsellers list!

No, if Smolin wanted to reach the physics community, there are better forums. Review articles in Phys. Letters or Phys. Review, for starters. Or an article on the physics online journal http://www.arXiv.org.

the operational safety issues can be ameliorated significantly by following adequate safety protocols (chernobyl only happened once), the question of 'rougue states' is somewhat irrelevent, because 1/ i doubt that they're any more happy about us having nukes than we are of them having nukes, and 2/ i doubt that third world countries will be amongst the first to develop hydrogen power (itll be the well developed countries, which allready have nukes, that adopt it first), and the disposal issues, whilst problematic, are a lot less environmentally damaging overall than coal-burning plants.

First, I tend to agree with you about building more nuclear plants. But we can't minimize the problems. The difficulty with a breach like Chernobyl is that if one occurs at, say, the plant just up the river from NYC, you put tens of millions of people at risk. In that case, any failure rate, no matter how small, becomes intolerable. And you put the plants near the cities so that loss from transmission is reduced.

Second, the problem of rogue states is very relevant. Remember, the use of petrol is greatest among the developing world, and that's where you have the rogue states. Since hydrogen is so tough to transport, Iran is going to want to have its own hydrolysis for its hydrogen vehicles. And that means nuclear plants in Iran. And we know how well that is working out right now and how well it has worked out in N. Korea. The chance of nuclear weapons being used increases with the number of states that have them. The odds that you will get ONE irresponsible state approaches 1. And, with several states (including the probable opponents) having nuclear weapons, then you get the probability of a nuclear exchange and nuclear winter. That's as catastrophic as global warming, right?

Of course, there is also the problem of security. The more nuclear plants, the more difficult to guard them all. And this the temptation for terrorists to attack a plant -- either to cause nuclear accident or to get their hands on the material. Just a few ounces of plutonium put in the reservoir of NYCs water supply, and the deaths are in the millions. Yes, plutonium is that bad a poison.

Third, the problem of waste disposal is such a long term problem. Isotopes with half-lives of millions of years. And don't forget the plants themselves. After 50 years of operation, even the pipes and walls of the plants are slightly radioactive as neutrons convert some of the atoms to radioactive isotopes.

plus, if a new, greener, power source is developed, it'll be easyer and quicker to replace the nuke plants rather than all the cars... H2 power, by putting the actual power generation all in one place, makes it easy to manage.

Didn't you read the problems of transporting H2? You can't put the power generation in "one place". You have to have electrolysis plants everywhere, and that means the power generating plants everywhere.

What you are saying is that environmental downside to nuclear plants is less than the environmental downside of coal or other petrochemical generating plants + the release of greenhouse gasses by cars. I agree with that, but it's not a slam dunk. It depends on how serious you think global warming is going to be.

Also, like it or not, nuclear plants are expensive. The safety improvements that you so blithely pass over add exponentially to the cost. That is, getting a 1% improvement in safety from 98% to 99% doesn't add 1% of cost, but multiplies the cost by several fold. For the foreseeable future, coal is SOOO much cheaper than nuclear power there is no way to economically do what you propose.

These motives are sporadic and would therefore slow expansion down. ... Also if you need adventure or religious motivations then these would also slow down the expansion.

 

If a species is to expand throughout the galaxy they will need a constant motivation to expand. Population pressure is one. ... Even this leaves a small window of opertunity for expansion as an increasing population will need more resources to survive and so the limit on the rate of resource aquisition will eventuall outstrip this' date=' making expansion too costly.[/quote']

 

SkepticLance keeps ignoring economics. You make the same point I've been making: sublight generation ships are expensive. And by "expensive" you are I are talking resources. Money is simply a convenient way of tracking resources. When resources (supply) are limited, then the price of those resources goes up. Basic supply and demand. As you pointed out, as population increases, you get calls to use the resources for demands other than a starship. We see that here on earth today: people want to stop the space program and use the resources to improve life on this planet.

 

As you noted, this means that a species is going to have a small window in time where there are spare resources to build a starship. If for any reason (such as political division like we have on earth), they don't build the starship, then they will lose the capability.

 

This short window of opertunity will also slow down the rate of colonization.

 

In the Novels (the original and the sequal) they discuss what would happen if the Moties got out or were able to use the FTL drives. Thye talk about the fact that the population growth would exceed the rate of expansion from the core systems and so war would break out. This war would then also spread to the outer colonies, and would reduce the rate of expansion.

 

Yes, and that was with an FTL drive. Unless the FTL drive was instantaneous to anywhere, even FTL has a finite speed. I discussed this in a reply to your previous post that the inner worlds could not ship their excess population out past the colony worlds. So you either have war with the colony worlds for settlement or the inner worlds collapse and the population (and civilization) is drastically reduced thru war and/or starvation. Now, since it is known that the inner words are inhabited and their location is known, it would be easier for the outer colony worlds to ship their population back to the inner worlds rather than expand outward.

 

In that case, you get an optimum sphere size of colonized worlds and continual shifting of population within the sphere -- which both you and I have pointed out before, but SkepticLance ignored.

 

There may be many reasons for expansion, but there are also a lot of things that would slow down the rate of expansion, may be even to the point of 0 expansion or even contration.

 

Right. As far as I can see, none of SkepticLance's reasons for expansion are inevitable. All of them have counteracting processes that would eliminate the motive/expansion or reduce it to a crawl such that the expansion has not gotten even close to earth yet.

lucaspa.

You are niggling me because I a suggesting a range of possible motives for going interstellar. We are talking about possible a million species and 2 billion years. There are possibly thousands of different motives for going interstellar. Any of them will do.

What you are doing is changing the argument in the face of falsifications. Another way of putting it is that you are introducing ad hoc hypotheses to try to save your hypothesis. Remember' date=' your claim depend not just on going "interstellar", but having a [i']sustained, continued [/i]colonization program using sublight transportation such that one of the species would have reached earth.

You need a motive that gives you continued colonizations/explorations. So far none of the suggested motives have withstood critical examination to give you the certain, sustained colonization. Accept that. Yes, you can maintain possibility, but the arguments against that are just as strong or stronger. Conclusion: there could indeed be a million technological species in the galaxy but, if we are limited to less than 0.5c, there are very good reasons why none of them have made it to earth.

the data does say that an alien species never made a LONG TERM -- billions of years -- colonization of earth. If they had, they would still be here! BUT, it doesn't discount a complete colonization of several million years a billion years ago[/i]

 

For God's sake, lucaspa. If a species was on Earth one million years, it would leave so much garbage that we would be living in their land fills!

You took out a key phrase. I put it back in italics. And why would those landfills be on the surface? How much of our planet has rocks from a billion years ago on the surface? C'mon, do some research and give us some data! Yesterday the news was that a new oil well in the Gulf of Mexico had come online. It was 20,000 feet below the surface. So, yes we could be living on their landfills -- but they are 20,000 feet below us.

OR ... those landfills have already been eroded. 500 million years ago the Appalachians were 40,000 feet tall. What do you think happened to them?

Yet we have not found a single artifact. And please don't throw crackpots at me. Their hypothetical artifacts would not fool a five year old. Right now, we have NO alien artifacts.

I would think you would leap at those artifacts, since they are support for visitation. However, would the artifacts still be here even a million years afterward. I've already pointed out methods of degradation. What artifacts do you think would be immune and would last for a million years, much less a billion?

Let's forget moties. It is fiction and thus irrelevent to the discussion.

But the economic, social, and biological consequences of unrestrained reproduction are not fiction. Think of the novels as a thought experiment and speculation. After all, it was YOU who pointed out that we are engaging in speculation. So Niven and Pournelle's speculation based on economic and biological realities are relevant. You just don't want them to be because those consequences refute your conclusion. That's not a good enough reason.

You proposed population pressure as the prime motive for colonizing the galaxy using ships at 0.2c. But the speculation is that such population pressure is more likely to lead to cycles of trying to feed the population followed by catastrophic war for resources, and then back to barbarism. Now, instead of trying to ignore the speculation, try to show why it is inaccurate.

However, I am suggesting a species that controls its numbers when it must, and multiplies when it can. Are you telling me that such a species is impossible when we talk about a millions species over 2 billion years. I don't think so.

I'm saying that if such a species exists, then economics will ensure that it controls its population before it gets critical and will remove the motive for colonization. This is where the studies on humans -- who fit your profile -- come in. Increasing wealth causes control of population -- because the individuals "must" control their population to retain their wealth. And a civilization technologically advanced enough to make the generation ship you propose will be wealthy. Thus, already controlling their population. And there goes your motivation. The planet is not overcrowded and there is no population pressure for colonization.

Now, you propose a 50 years hop of 4 light years. BUT, we don't know that Alpha Centauri has planets. Is it even theoretically possible to detect an earth-like planet at that distance? I doubt it, but you can do the research to show me wrong. So, the ship can't just be engineered for that hop, can it? If Alpha Centauri doesn't have planets, then they have to keep going ... for they don't know how long. You can't engineer for that. You have to control population.

The way to determine habitable planets would be to send a probe. That's at least 50 years out and 4 years transmission time back ... assuming nothing bad happens to the probe. So, 54 years before launch of the probe until you even know if you can launch the colonization mission. Economically, there is no use even building a ship until the info is back and is positive. So now you have construction time. By this time, any political or social motivation for colonization has probably gone away.

by that logic, i may as well live in a chimney

And, if pollution continues, you will be!

However, some of the pollutants are greenhouse gasses. Since burning coal is still the cheapest form of generating electricity, even if you use hydrolysis, that means burning a lot of coal to make the electricity to make the hydrogen. And global warming is indeed global.

skepticLance why not just make and store electricity when the wind's blowing, and use it when it's not?

How do you store electricity? Batteries are the only method I know of now. Of course, making hydrogen and then using hydrogen fuel cells would be another method of "storing" electricity. But now you have the problem of transporting the hydrogen. And that's not trivial.

whats wrong with using nuclear plants?

Besides the operating safety issues and the possibility of releasing large quantities of radioactive and toxic materials a la Chenobyl? The tendency for rogue governments to use the plants to make bomb-grade uranium or plutonium (as Iran is suspected of doing)? How do we dispose of the spent fuel rods -- highly radioactive and toxic? And what do we do with the radioactive plant itself after it's worn out?

Remember, plutonium is several times more toxic chemically than cyanide.

Other than all these problems, there's nothing "wrong" with nuclear plants.

Hence why the hydrogen plant would have to be right next to the power generation plant. I haven't, however, accounted for the distribution of the hydrogen, which adds to its environmental cost - although gasoline goes through the same process as well.

But the problems are much bigger with hydrogen.

"That is, if such a pipeline were even practical to build. Given

hydrogen’s low density, it is far harder to deliver than, for instance,

natural gas. To move large volumes of any gas requires

compressing it, or else the pipeline has to have a diameter similar

to that of an airplane fuselage. Compression takes work, and

that drains still more energy from the total production process.

Even in this instance, managing hydrogen is trickier than dealing

with other fuel gases. Hydrogen compressed to about 790

atmospheres has less than a third of the energy of the methane

in natural gas at the same pressure, points out a recent study by

three European researchers, Ulf Bossel, Baldur Eliasson and

Gordon Taylor.

A related problem is that a truck that could deliver 2,400

kilos of natural gas to a user would yield only 288 kilos of hydrogen

pressurized to the same level, Bossel and his colleagues

find. Put another way, it would take about 15 trucks to deliver

the hydrogen needed to power the same number of cars that

could be served by a single gasoline tanker. Switch to liquid hydrogen,

and it would take only about three trucks to equal the

one gasoline tanker, but hydrogen requires substantially more

effort to liquefy."

"Among hydrogen’s disadvantages is that it burns readily. All gaseous fuels

have a minimum and maximum concentration at which they will burn. Hydrogen’s range is unusually broad, from 2 to 75 percent. Natural gas, in contrast, burns between 5 and 15 percent. Thus, as dangerous as a leak of natural gas is, a hydrogen leak is worse, because hydrogen will ignite at a wider range of concentrations. The minimum energy necessary to ignite hydrogen is also far smaller than that for natural gas. And when hydrogen burns, it does so invisibly. NASA published a safety manual that recommends checking for hydrogen fires by holding a broom at arm’s length and seeing if the straw ignites."

Quotes from same article as before

The point is that the plant in Wyoming would be more efficient than the car in LA, meaning that less pollutants would be emitted for the same energy use (theoretically).

You are thinking in terms of generating electricity. Instead, think of pollution in getting hydrogen from coal.

However, even in terms of hydrolysis, do you seriously think that renewable energy sources such as wind or solar are going give enough electricity to get the hydrogen you need? Remember, we use about 13 of million barrels of oil a day just in the US for fuel for cars and trucks. Think of how much hydrogen that is.

"Hydrogen is also about five times as expensive, per unit

of usable energy, as gasoline. Simple dollars are only one speed

bump on the road to the hydrogen economy. Another is that supplying the energy required to make pure hydrogen may itself

cause pollution. Even if that energy is from a renewable source,

like the sun or the wind, it may have more environmentally

sound uses than the production of hydrogen. ...

"Hydrogen could be derived from coal-fired electricity,

which is the cheapest source of energy in most parts of the country.

Critics argue, though, that if coal is the first ingredient for

the hydrogen economy, global warming could be exacerbated

through greater release of carbon dioxide.

Or hydrogen could come from the methane in natural gas,

methanol or other hydrocarbon fuel [see illustration on page

72]. Natural gas can be reacted with steam to make hydrogen

and carbon dioxide. Filling fuel cells, however, would preclude

the use of natural gas for its best industrial purpose today: burning

in high-efficiency combined-cycle turbines to generate electricity.

That, in turn, might again lead to more coal use. Combined-

cycle plants can turn 60 percent of the heat of burning

natural gas into electricity; a coal plant converts only about 33

percent. Also, when burned, natural gas produces just over half

as much carbon dioxide per unit of heat as coal does, 117

pounds per million Btu versus 212. As a result, a kilowatt-hour

of electricity made from a new natural gas plant has slightly

over one fourth as much carbon dioxide as a kilowatt-hour

from coal. "

But this isn't the end:

"When natural gas is cracked for hydrogen, about 40 percent

of the original energy potential is lost in the transfer, according

to the DOE Office of Energy Efficiency and Renewable

Energy. Using electricity from the grid to make hydrogen by electrolysis

of water causes a loss of 78 percent."

So, since most electricity is generated by coal-fired plants, that's a lot more release of greenhouse gases to make the hydrogen because the process of electrolysis is so inefficient.

All quotes from "Questions about the Hydrogen Economy" in Scientific American, May 2001.

BTW, when I mentioned binding metals to hydrogen for storage, my fuzzy memory was also thinking of metal hydrides as a way to store hydrogen. That's also in the article.

The plant in wyoming need not be a petrol plant. it could be a nuclear plant, thus significantly reducing the amount of polution produced powering x cars.

The plant is Wyoming is the one converting coal to hydrogen. It is that process that produces the pollution. It's not the generation of the electricity that is the problem; it's the production of hydrogen from coal.

Now, if you can get power to do electrolysis on the scale needed for all the cars out there, then that is a different story. But the problem so far is that no power source generates that much electricity. So instead you use less power and get hydrogen from the huge reservoirs of coal -- hence Wyoming. But that gives you lots of pollution -- both air and water.

BTW, if you are generating hydrogen by hydrolysis, then the plant is on the shore of an ocean. After all, you don't want to use fresh water -- that too is a scarce resource and getting scarcer.

lucaspa

 

All you said was that you did the sequence. You didn't tell my why it is valid to do so. The results don't justify the method.

 

The method matches TFQHE for electrons and predicts the mesons fractions using the same method.

Still doesn't tell me if the method is valid. Walk me thru why this isn't apples and oranges and the results are not coincidental.

The "waves" in particles and atoms are probability waves

 

True in QT but my work is done in classic theory where the waves are observed by experiment (TFQHE).

Irrelevant to my point. You are talking larger "waves". But the "waves" in QM are not the same as waves in classic theory. So to say that they (the waves) are equivalent is wrong. REmember your claim: that the waves in QM are the same as "cosmic waves". But since "waves" isn't being used in the same way and isn't the same phenonomon in QM and macro observations' date=' you can't make them be the same.

Also you still haven't told me what waves are observed for the "universe".

It seems that you have just defined everything as having nucleus and shell. I would not call the quarks that make up baryons to be a "nucleus" and "shell".

 

This is where I part company with QT there assumptions on quark structure are wrong.

Irrelevant. I am addressing the use of language. You are saying "nucleus" and "shell". We are not discussion the structure of quarks themselves, but whether the composition of baryons corresponds to a nucleus with an outside shell -- which is the structure we see in atoms with a nucleus and a shell of electrons. Are you saying there is an equivalent structure in baryons? If not, then don't use "nucleus" and "shell".

Just defining things the way you like isn't looking for what the universe really

 

I think that producing a theory that matches experiments is science, producing a theory that accurately predicts but does not explain is accurately defined as mathematical philosophy.

Again, irrelevant. You didn't address my point. To address my point you have to show that you are not just defining things to be the way you like. That there really is a nucleus and shell, not just defining them that way. That the universe does have classical waves, not just defining that it does.

Also, "producing a theory that matches experiments" is the same as "accurately predicts". Those are 2 ways of saying the same thing. Yet one you call "science" and the other "mathematical philosophy".

You are doing emotive work, not looking at what really is and what is really being said. And doing emotive work is not doing science. No wonder you have to hawk your theory on the Internet and not put it up for peer-review.

Hi Severian' date=' lucaspa!

 

the only review I've seen of Smolin's TwP book that I would even call a review (surveying the whole book, identifying the main themes, trying to judge what it really says) was by a German woman who is a Quantum Gravity phenomenologist----Sabine Hossenfelder

 

She goes by the name of Bee. here is Bee's review, if you are curious:

http://backreaction.blogspot.com/2006/08/lee-smolins-trouble-with-physics.html[/quote']

 

Thank you. This discussion within physics reminds me of the debate over heliocentrism. When Copernicus proposed that the sun was the center of the solar system and all the planets orbited the sun, there wasn't any data for it. Because people were still using circular orbits for the planets in heliocentrism, the data didn't fit heliocentrism.

 

In fact, the appeal was emotional -- the universe was SO much bigger than people thought.

 

There followed a 50+ year period where people argued whether heliocentrism was correct., but no one had the data or the theory to convince the others.

 

This looks similar. String Theory has an emotional appeal: source for the physical "constants", unification of Relativity and QM, and an expansion of the universe to new entities (strings and 'branes).

 

It's obvious that some funding is going to alternative ideas. After all, Smolin has a job. So does Milgrom (modified Newtonian mechanics). It sounds like Smolin wants more of the pie.

 

My objection is that Smolin took the debate to the lay public instead of fighting it out among physicists. There was no point. Politicians are not going to read the book (to change the funding priority); scientists know the controversies from within science. Therefore the book becomes another attack on science. Science doesn't need that.

Discounting his opinion... hard to say... but if being obnoxious, unprofessional, unproductive and childish isn't reason to ignore someone, what is?

Being contradicted by the data. That's the ONLY reason to discount an opinion within science.

We learned this with Galileo. It was his obnoxious, unprofessional, unproductive, insulting, and childish attitude that got him in trouble and caused his fellow scientists to bring charges against him.

Now, all the qualities you named can lead you to suspect that the data contradicts him. After all, if the data were on his side, he needn't resort to those tactics. However, you still have to show, by the data, that the ideas are wrong.

Ahh' date=' ok, I undestand now. Thanks.

 

Although I do remember reading an articla in new scientist (about a year ago I think) about changes in protiens and other non DNA changes being passed on to the ofspring (in the aricl I it even said that some foods might have chemicals that can cause these changes).

 

I can't remember exactly when, and I don't have the magazine anymore, but it does seem that some non-DNA changes might be passed to the ofspring.[/quote']

 

I subscribe to New Scientist (it's free, so you can also) and get New Scientist in digital form. If you can even get an idea of the month last year, I can look the article up. Absent the article, I don't see how non-DNA changes can be passed to an offspring.

 

Some foods contain mutagens for DNA -- grilled meat is one of these. Other foods contain anti-oxidants. These can help prevent mutations to DNA. So a person eating a lot of anti-oxidants is less likely to have these oxidative changes to DNA. Other than that, I can't think of anything I have read that would be even close to what you are saying.

I have been looking for the reference to the paper' date=' but am not able to find it. It was around 5 or 6 years ago (so I can;t bring the exact details to mind). If I remember correctly it was an article in New Scientist or some other magazine like it, that referenced an aricle in "Nature".

 

In the aricle they described research into the "Mad Cow" deseaes and how they worked. Mad Cow is caused by a missfoled protein that causes correctly folded proteins to be folled in the incorrect way (thus spreading the desease). The reserchers also found that some proteins cause missfolded proteins to be folded correctly. This research answered one of the puszzles about protein folding and how protiens "knew" how to fold correctly.[/quote']

 

OK, this is different than correcting a "mutated protein". A mutated protein is one where the amino acids have been changed by a mutation to the sequence of bases in the DNA.

 

When translation occurs, the DNA is first copied to messenger RNA. The mRNA is then moved (translocated) from the nucleus to the cytoplasm and to the ribosome. The ribosome actually makes the protein, but does so by adding one amino acid at a time. Thus the protein comes out as a linear chain. Do you know about R groups on amino acids?

 

Anyway, because of the differnt ways R groups interact with water, the linear protein chain folds into a 3 D structure. However, sometimes they need help. There is a class of proteins called "chaperones" that help proteins fold. They were first discovered in looking at transport of proteins into mitochondria. The proteins unfolded to get thru the membrane, and then had to re-fold:

 

"Since the 1950s, scientists have known that the information necessary for a protein to fold properly is encoded in its aminoacid sequence. However, in the past 15 years, researchers have discovered that matters are not quite that simple within cells. “In 1987, we were studying how proteins got into mitochondria”, says Arthur Horwich (Yale University School of Medicine, New Haven, CT, USA). “It was becoming clear that for this to happen, proteins had to unfold so that they could get through the mitochondrial membranes rather like a strand of spaghetti. The question we and others asked was ‘Do proteins spontaneously refold once they get into mitochondria or is some sort of machine needed?’”

 

Cells were soon discovered to have several such machines—called chaperones—that assist protein folding particularly when cells are exposed to stresses such as heat. Chaperones, explains Horwich, are proteins that have hydrophobic surfaces that recognise and bind to the exposed hydrophobic surfaces of improperly folded proteins. “This prevents non-native [misfolded] protein molecules making wrongful interactions with other molecules of the same sort”, a process that could cause aggregation, says Horwich. “Small proteins probably don't normally need chaperones to fold, but large complex proteins need kinetic assistance." " Chaperones: keeping a close eye on protein folding Jane Bradbury, Lancet 361: 5 April 2003, Pages 1194-1195

 

What is confusing you is that several researchers are hoping to use chaperones to combat genetic diseases where they think the effect of the mutation is to cause misfolding of the protein. They want to design chaperones to cause the misfolded protein to refold the correct way. This would, in these particular cases negate the effect of the mutation. It doesn't "correct the mutation" = changing the DNA back to what it should be, but it would stop the disease effect of the mutation by restoring the protein to the correct folding.

 

The offspring of a person with the genetic disease would also have the disease, because the DNA had not been changed.

 

There are several problems:

1. To correct the folding, the chaperone has to associate with the protein. But then the protein can't function. So the chaperone would have to dissociate after correct folding was achieved. Will this happen?

 

2. How long would the corrected folding last? After all, the incorrect folding was the way that the protein wanted to fold -- it was the preferred folding and reprsented the lowest energy state. So it follows that the protein would unfold a little and then refold back to the non-fuctional folding.

 

3. Will the chaperone be able to help at all? "once mutation enters the scene, the ability of any protein to reach its native, active state is strongly affected.” It may be impossible for even a designed chaperone to help.

 

Now, I have seen recent research that indicates hopeful preliminary data on designed chaperones to lessen the effect of a few genetic diseases.

 

"Also under investigation is whether molecular chaperones—the cell's ownchaperones—can be used to fix protein misfolding problems. Ulrich Hartl (Max Planck Institute of Biochemistry, Martinsried, Germany) is optimistic. He is studying polyglutamine diseases, in which genetic expansions of the nucleotide triplet CAG lead to long glutamine stretches in the encoded protein.

 

“When the polyglutamine expansion in proteins such as huntingtin exceeds about 40residues”, he explains, “its normal random coil-like structure adopts a conformation rich in β sheets. These can align regularly and form the fibrillar amyloid structures responsible for the disease process.” Hartl has shown that in vitro and in cells, increased expression of molecular chaperones—in particular, Hsp70—can suppress the cellular toxicity of polyglutamine proteins.

 

To achieve Hsp70 upregulation, Hartl used the drug geldanamycin, as has Nancy Bonini (University of Pennsylvania, Philadelphia, PA, USA) in her in-vivo studies on neurodegeneration. “We had already shown that Hsp70 expression in a fly model of a polyglutamine disease suppressed pathogenicity. As a proof-of-principle we wanted to see whether a drug that could boost chaperone activity could do the same.”

 

Working with a drosophila model of Parkinson's disease, Bonini found that geldanamycin treatment protected the flies against dopaminergic neuron loss.

 

Geldanamycin is too toxic for clinical use, particularly given that for conditions such as Huntington's or Parkinson's disease repeated doses would be needed to prevent the toxic effects of protein aggregation. And both Hartl and Bonini comment that no-one knows what other effects tampering with Hsp70 expression will have."

 

But none of this happens naturally. It requires human intervention and, to emphasize once again, the mutation is NOT corrected in the sense that the DNA is changed back to its original, pre-mutation sequence.

On point 1. Dak is correct. Controlling pollution in a factory is easier than in small motor vehicles. Nitrogen and sulphur oxides can be scrubbed out.

That isn't how the article described it. The pollutants can't be scrubbed out. They are just going to be emitted. It's just that they will be emitted from a plant in Wyoming instead of in LA.

Now, since the entire world is our "doorstep", I don't see how this helps. Yes, the smog in LA is less, initially, but then the entire planet becomes LA. This is progress?

In the near future, carbon dioxide will be pumped into very long term underground storage. Some researchers are even working on ways of bubbling the carbon dioxide through ponds filled with algae to remove the nasty gases.

What "nasty gases"? The plan would remove the CO2 -- the idea is that the algae convert it to sugar and oxygen thru photosynthesis.

Fusion power would be lovely. However, no scientists working in the field suggest it would be available before 2050 at the earliest. See the latest (September 2006) Scientific American for a good article on this subject.

I know. I said we needed it, not that we were going to get it.

Point 2. Hydrogen storage by metal bonding is a great idea, but it is not yet available. At this point in time, we can only use tanks.

I stand corrected. I misremembered the role of platinum in fuel cells. It's not to store hydrogen, but provide a catalytic surface for the electrochemical reaction. http://www.howstuffworks.com/fuel-cell.htm

Cars will have to have the high pressure storage, which means some leakage. Hydrogen doesn't need a crack -- it is small enough to diffuse thru a metal. But the leakage is going to be small compared to the amount of hydrogen used by the car.

lucaspa

The coal to hydrogen approach is only one way of doing it' date=' and as you said, not a smart way.[/quote']

 

But the only way now to get the quantity needed to fuel all the cars in the world.

 

Electrolysis by wind simply isn't going to generate anything like the quantity needed. Nuclear is theoretically an option, but the cost of nuclear plants is so high and the problem of waste disposal so tough -- economically and politically -- that it isn't viable to build enough plants to make enough hydrogen.

 

What we need is cheap fusion power. Then we can make all the hydrogen for all the fuel cells we could possibly need. Just one small problem ...

Lucaspa said :

 

Your argument on the presence of alien artifacts rests on the assumption that the geological record is complete.

 

Of course not! I have a degree in biology and a good understanding of fossilisation and its consequences. Probably only one organism in a trillion or less ended up as a fossil. There are heaps of gaps. What I am saying is that if an alien species is living on Earth' date=' it will inevitably leave vast amounts of materials (garbage) that is non-biodegradable - hence prime candidate for preservation. The vast bulk of that rubbish would never be discovered. However, it is inevitable that at least a few bits and pieces would turn up.[/quote']

 

1. You contradict yourself. If rubbish would turn up, then why not fossils of all those "gaps" in the fossil record. The reasons for the gaps also explain the lack of rubbish. Same reasons to explain the same type of lack of data. As I said, the data does say that an alien species never made a LONG TERM -- billions of years -- colonization of earth. If they had, they would still be here! BUT, it doesn't discount a complete colonization of several million years a billion years ago or a small colongy from 50 million years ago on back \and a visitation (but not colony) anytime in the past.

 

2. There are ways that degrade the rubbish. Fossils persist because they turn to rock. Coke bottles don't. Instead, metals rust and/or melt during metamorphosis, plastics degrade, and glass is ground to dust.

 

3. Of course, if you visit creationists websites, they do post what they claim are artifacts -- what you call "rubbish". Why do you discount them?

 

Haven't been paying attention to the immigration debate, have you? It's not "small numbers" of illegal immigrants we are looking at. Nor was it "small numbers" of Europeans that came to America in the late 1800s.

 

Everything in this world is relative. My use of the term 'small numbers' was clearly misleading. Sorry. The small size of those numbers is relative to the large size of the numbers left behind. Unless there is something massively traumatic (like the Irish potato famine driving people to America) the percentage of those emigrating is small.

 

I do not believe for a moment that a species as immensely capable as the moties could remain trapped on their world as Niven describes it.

 

Niven and Pournelle thought the matter out carefully. They always do. You "do not believe it for a moment" because it goes against what you want to believe. In the biological and physical situation postulated, there is no way for the Moties to get out of their system by sublight. Their population growth means that there aren't spare resources available to build a generation ship. Any Master trying to build one is going to either 1) be conqueored by a neighbor who puts resources into the military instead of a generation ship or 2) the resources are needed to feed and provide the other necessities of the expanding population.

 

The tramline system of faster-than-light is immensely cheaper and it is relatively cheap to build a ship to do that. However, due to the special spacial circumstance in the novel, the Moties couldn't use it (they came out inside a star). But we are discussing a universe where faster-than-light is completely impossible and species are restricted by physics to sublight. In that situation, the economic situation facing the Moties would apply to ANY species unable to control their population.

 

Our discussion recently was in relation to a world that already had a Dyson swarm. The economics in that situation are simple. In spite of your assertion that such a habitat is not a generation ship, it would, in fact, be relatively easy to convert. Essentially, all that is needed is an independent energy source such as a fusion generator, and suitable size ion drive engines (or some futuristic equivalent) strapped on. The habitat is already set up for long term survival.

 

You forgot the modifications to enable it to survive interstellar debris.

 

However, as I pointed out, any species building a Dyson swarm has no motivation for going interstellar. You ignored my extensive discussion of that point.

 

For one thing, it is going to take millions of years to exhaust the available living space offered by the swarm. Just think of the surface area! Those city habitats are going to have, in their volumes, billionsof times the surface area of the earth! For tens or hundreds of millions of years, whenever population gets too high in a ship, just build a new ship and put it into orbit next to them. Only when the entire swarm is such that it fills all available orbits around the sun will the species even begin to feel crowded.

 

Each habitat, for the economic reasons you are so fond of, will be large, and will be independent in terms of food and oxygen generation (assuming they are oxy breathers). If they follow a pattern similar to human, each will have a leader, or small group of leaders. Again, if they are similar to humans, it is inevitable that charismatic leaders will appear from time to time, and some of them, for religious or other reasons, will promise to take their people to a promised land.

 

I see you've just tried to introduce a new motive. Sounds like you are beginning to see the fallacy of the "population growth" argument.

 

However, within the system, they don't have to GO anywhere. Just make a new ship and put it into orbit. In effect, they are already in their "promised land". Your argument only works until all available orbits are taken. Also, notice that you now have the whim of individuals, not an inevitable reason for expansion.

 

Now, also remember, in order to undertake the interstellar trip, they must have population control. Otherwise they will starve or use all the breathable air. Between the stars, there is no source of new air -- no recycling system can be perfect (second law of thermodynamics). So what you have is all you've got. Population growth exhausts those resources and everyone dies. So, in order to even consider an interstellar trip, they have a means of controlling their population.

 

BUT, this means that the time to filling all the orbits in the Dyson swarm gets stretched out even more. Instead of tens of millions of years, it may be billions of years or never. They may never get all the orbits filled.

 

Instead of an inevitable expansion, you are down to another fraction: those species who have such an adventurous spirit that a whole city habitat will decide to invest in the danger, unkowns, and cost of conversion to take one of the city habitats on an interstellar exploration and colonization effort.

 

If, over a 2 billion year period, there are very large numbers of such species, then at some stage, this diaspora will occur.

 

Nope. Not certain at all. After all, over 2 billion years, very few species will have even filled their Dyson swarm orbits.

 

If, on the other hand, the species we are discussing, never gets to the stage of building a Dyson swarm, then there is every chance it will build space habitats anyway. When that happens, they will move those habitats to where raw material is available. Their equivalent of asteroid belts, Saturn's rings etc.

 

Wait a minute. In order to find the materials to build enough ships to have a complete Dyson swarm, you need the raw materials and all the planets in that solar system will go into the effort. The atmospheres for the necessary gasses and the body of the planet for the structure of the ships. In which case the it takes even longer to have population pressure! We are assuming filling a hollow sphere of approximately Earth's orbit. If you expand that volume, then you correspondingly increase the area of living space.

 

Once you have Dyson swarm habitats, you have no MOTIVE to go interstellar!

 

Today, there are more people living in Europe than there was 200 years ago, showing that there was room for more people in Europe, at the time so many were leaving. Yet a lot of people left Europe to go to unknown and potentially hazardous places to live. Motive is more than just; "have I got room to live, and enough bread on my table?" Remember, it is always a small percentage that leaves. It is always the most adventurous and entrepreneurial that do so.

 

So, you have abandoned the motive of population pressure. Now you are talking about economic and adventure motive.

 

Notice that people in Europe aren't emigrating anymore. Why? The economic and political motives are gone. There is enough wealth and political freedom so that people are content where they are. Similarly, people don't emigrate much from the United States. Emigration is from places that are poor and/or have political problems.

 

But, a civilization able to build a Dyson swarm is technologically advanced. This means that everyone is going to have enough wealth. The political aspect is taken care of with people having their own city habitat ships. Don't like the political system you are under? You don't have to build a ship to go to the stars, just build another city habitat. And you can start out small and add on later. A LOT cheaper than building a generation ship.

 

So, this leaves adventure. However, even adventurers had economic motives of greater wealth. Columbus wasn't exploring for the sake of exploring -- he was looking for a new route to the spice islands. How is this achieved by a one-way interstellar colonization trip? You already have wealth at home. If you desire more, there is opportunity there. If you want danger, work on the Jupiter type planets mining material to build new habitats.

 

All in all, any civilization that is capable of building in-system city type habitats has no motive for interstellar colonization. It doesn't even have motive for interstellar exploration. There is nothing out there that would convince people to invest the money in a ship that is never going to come back and realize a profit on the investment.

Come on - the guy is a respected physicist. You may disagree with him, but to completely discount his opinion, and urge others to ignore him, is a bit much.

The review did seem a bit strident and intolerant to me. String Theory is not as rock solid as Motl makes out. He must have had a cow when he saw: 5. Kaku M, Testing string theory. Discover August 2005 http://www.discover.com/issues/aug-05/cover/ There are also papers in physics journals that I've seen that indicate that the predictions made by String Theory are not being found.

Instead of stating Smolin's remarks on how to reform science, I wish Motl would have quoted Smolin instead of making these statements:

"In the sociological part of this book, Smolin complains that no one takes him seriously and tries to paint the mainstream physics community as a group of evil people. Also, he proposes "cures" for the things that he views as "problems". This includes new ethical standards of the science community. For example, one of his rules says that conclusions must be accepted by everyone if their author is a person of good faith. Another rule, apparently applied to the other theories, says that they must first present a full rigorous proof. "

These are very serious charges. They need to be documented by quoting Smolin instead of just saying that Smolin said this.

I personally think Loop Quantum Gravity is a cool idea. Don't know that it is correct, but then I don't know that String Theory or Randall's 'branes are correct, either. The data simply isn't there to say one way or the other. But scientists do get overly emotional sometimes when defending and attacking ideas. Look at the Gould vs Dawkins animosity.

Not every scientist is as rational as Milgrom:

"As its inventor, I would like it [MOND] to be a revolution, but I look at it coolly," says Milgrom. "I will be very sad, but not shocked if turns out to be dark matter." C Seife, Radical gravity theory hits large scale snag. Science 292: 1629, June1, 2001

its competeing with physics textbooks and physics popularizations, if you scroll down you'll find the elegant universe and other such books. I wonder where it is on the the big list of best sellers.

Again, this is good because ...

Implicit in your sentence, but unstated, is that Smolin's book is somehow exceptional. Why?

looking towards the future' date=' the switch to hydrogen power would be good, to take advantage of any future, green energy sources. also, now it would at least get the pollution away from the people. if we [i']are[/i] going to pollute, i'd rather it be done somewhere away from me.

 

one thing thats always concerned my about the idea of hydro powered cars: say you have a full tank and crash, rupturing your tank. wouldnt that be an almightily big explosion?

1. Moving the pollution doesn't really solve anything, does it? Since it is atmospheric pollution, it is going to get to you eventually. What we need is fusion power. Then we would have enough cheap electricity to hydrolyze water for hydrogen. Until then, the current methods of cooking coal just makes more pollution.

2. There are ways now to keep the hydrogen bonded to porous metals -- titanium is one, I think. Thus, you don't really have a pressurized gas in a fuel cell like was in the bags of the zeppelins. No more danger of explosion than you have with gasoline powered cars -- maybe less.

Why are we unable to power our cars with water? Is the technology just not ready yet, or is it physically impossible?

We use gasoline because it combines with oxygen (a process known as combustion) and combustion gives off heat and forms a gas that expands. This expansion moves the cylinders.

Now, think about it. How is water formed? It is the end result of combustion! That is, water is formed by hydrogen burning with oxygen. Thus, all the heat has already been given off!

In hydrogen fuel cells, the end result is water. And electrolysing water takes far too much energy -- think of how much energy is given off in a hydrogen flame -- so separating the hydrogen and oxygen requires at least that much energy. Where does that energy come from?

Currently, the idea is to heat coal in the absence of oxygen so that hydrogen is given off. That will be the source of hydrogen in fuel cells. A problem is that this process gives off more pollution than burning gasoline in cars. The politicians like Bush who push the scheme hope you are too dumb to realize this. Yes, less pollution in cities where the fuel cells are used, but more pollution overall that comes from the plants making the hydrogen. Scientific American had a good article on this about 2 years ago.

I was reading the part of the article that says:

 

 

 

I thought that part of the article was very funny...

 

Do kangaroos even lay eggs?

No. They are marsupials. They have live birth, but the young are so underdeveloped that they crawl into the mother's pouch -- which contains a nipple -- to suckle and finish developing.