Royston

I'm not convinced of the usefulness for an undergrad.

1) You (or at least "I") learn much more from attending talks, seminars, workshops, and conferences (or any other form of human-human interaction) than you do from reading papers.

True, but that's clearly beside the point...the context of the thread is finding information that is (for the most part) trustworthy.

2) If you're citing a paper in your work based only on (a) being on a topic somewhat related to your work, and (b) being published in a "list of reputable journals" then you should perhaps not cite it at all. If you're citing something because you rely in the information therein, then "I use it because it is listed in an okay journal" is not sufficient. If you cite a randomly-found paper solely based on being published in Nature and having 150+ citations because you have to fill the "overview over the field" section of your thesis, then you clearly have no overview over the field (which in many fields would actually be a lame thing to expects of someone below lecturer level, anyways).

I can't see that I even argued that, or more to the point, why you assumed that I was arguing that. As much as it's reassuring that my citations are not based solely on the source, or a tentative link to the subject, I still can't see why (from an undergrad perspective) that a name and shame of certain journals would not be useful. IOW, I simply don't have the technical ability to differentiate nonsense from legitimate. Sticking to reputable journals, at least, increases the probability that the information is more trustworthy than a free-for-all journal.

3) I do admit that one can feel very helpless when trying to find suitable interesting, readable, and helpful research papers about a topic, and fully understand why one would ask for assistance in this task. I do, however, believe that it is the duty of the research group (and in particularly the supervisor) to provide this help. Not in the sense of "here, read these papers I printed out for you", but at least in the sense of "Yin&Yan did something on this in the late nineties".

I guess, but one of the main learning outcomes of my dissertation, is that you have the ability to use and facilitate checkable and credible sources. So it is (to a certain degree) up to the student.

4) Let's face it: Already as of today Google scholar is probably more efficient at telling useful papers from useless ones than a compilation of "reputable journals" could ever be.

That really depends on the search term.

Besides, the only reason I've devoted 12 hours of my time each day to investigate complicated AGN feedback that agrees with cosmological timescales, is to say, hey look, I study astrofizzics....aren't I clever.

Hi,

i have been reading about iraq wars since my childhood. And there have been also many hollywood movies made about gulf war. But i just came to know that iraq which gets mention as bethlehem is infact a population of white skin african race muslims. So on tv and in media they show iraqis as good english and urdu speaking country, but infact is a african language speaking country but white in color. So their habitual lifestyle living is very much similar to africans, algiers, tunisia, algeria..etc.

So does americans have an affinity towards african like countries like nigeria, iraq etc???

Hi eric,

Muslims are a highly evolved alien race who descended from the planet, Klackshudrrrr. They were transported to Earth through a collimated proton beam.

I found one the other night, disguised as a used tissue. Luckily I managed to fend it off, before it's huge throbbing proboscis entered my face and forced me to write unintelligible shite on a science forum.

I've been buried in research, so sorry for the late response...but thanks all for the replies.

Who decides? How do they decide? This list of yours would be elitism, no doubt, and who would make it? The publishers of the "good" journals? There are de-facto lists of what's good and what's bad, but it's generally word of mouth.

I guess from my perspective, it's grabbing information that is 'to the best of my knowledge' (and therefore) less likely to be littered with poor papers. It's not so much elitism, more, it's the best I can go on (at my level). I can see why it would be considered elitism, but I'm perfectly aware that the peer review process is far from water tight.

Cha-ching! There's lots of money to be made by publishing hokey journals, particularly if you just pretend that you have a peer review process and don't have technical editors.

I overlooked the money aspect...so all I need is a web designer and a Baez filter

I think the people mainly interested in such a list are people not active in the respective fields of research, who happen not to be the target audience for research journals.

I'm not sure how broad a statement that is, i.e whether that's applicable to other fields of science (over physics). But again, from an undergrad point of view, would such a list not be useful ?

Nobody would believe that papers published in "reputable journals" are automatically legitimate, whereas those are not published therein are automatically crap.

Of course not, I gave the Lancet example for a reason. However, I agree with your other points, except that Perelman had reached notoriety in the mid nineties, long before his work on the Poincare conjecture.

This thread was prompted in part by this...open challenge and that I'm currently working on my dissertation, which has clocked up more than 60 references so far.

I've been quite strict in my sources, i.e sticking to what I feel are reputable journals e.g MNRAS (Monthly Notices of the Royal Astronomical Society), Astronomy and Astrophysics: a European journal, IOP et.c. My research has branched into (for me) unfamiliar territory such as experimental plasma physics, and simulation software and computational models for astrophysics. I've found that experimental data is harder to access over theoretical work, which is understandable, considering how prolific crack-pottery is.

Now, I realise certain papers leak through into reputable journals. A good example that led to the media shit storm was the MMR link to autism, that was originally published in Lancet, that swiftly got rebuked and debunked. I'm sure there are other such instances.

This leads to a few questions.

There is no definitive list as to what compromises a reputable source of scientific papers...why not ? I've come across the argument of impartiality, but this doesn't hold water for me...if you simply have something to go on, then why hasn't it been accepted by the more (so-called) rigorous journals. The argument that there is some elitism within science, is so littered with flaws, that I'm not sure where to start.

And, why is there this seeming proliferation of hokey sci journals popping up over the last few years. I don't get it...more avenues for espousing crap claims is just that, more avenues. The only effect it has, is that a slightly larger percentage of people are misinformed, it doesn't lead to new technology or advances in science, so is such a thing really dangerous ? IOW, has science gone about it's business regardless of popularity, or is there something I'm missing ?

The polar opposite of burying your cat, after it's been run over...

Anyhow here's my question

 

I'm doing s104 which is a introduction to all the basic sciences and fancy myself either working in chemestry or physics the problem is I did my gcses about 15 years ago. I've already got myself a gcse book on maths to remind myself what's what other than basic addition subtraction and multiplication and some percentages I havnt used any maths since school and am pretty rusty ( I did the open uni are you ready section and was confused with how to add and subtract fractions after a little internet snooping it all came back.

 

Anyhow could anyone suggest some of the more basic books to introduce me once again to chemestry and physics ? I forgot my periodic table so very basic is good . I did remember about adding atoms like h2o is 3 atoms 2 hydrogen and one oxygen and managed to work out what chlorine was made up of however as you can see I'm rather lacking in skills.

 

As for physics sadly other than basic magnetism I honestly don't recall anything I did at school so would have to pretty much relearn it all again.

I studied S103 (just over six years ago) and have a couple friends who studied S104. The topics are pretty much explained from the ground up. Admittedly I didn't do any preliminary study...(neither did my friends) but it's definitely a good idea to be prepared. I think getting hold of some GCSE text books is a good idea, so get one for each discipline i.e maths, physics, chemistry, biology and geology. The BBC GCSE bitesize site would be a good place to test your knowledge once you've worked through the books.

Good luck ! I've been with the OU for over 6 years now, and I've never looked back. It's been a very rewarding experience and is very addictive.

EDIT: Also, remember you can ask on here if you get stuck on anything...I'm sure somebody would be more than happy to help.

How does that make Issac less of a religious man, or his works less scientific in nature?

My point was, that you used an example where there was much greater pressure on people to believe in god (religion was far more ubiquitous in the UK back then). In any case, Newton wasted a lot of time writing theological nonsense. That time could of been better used contributing even further to science...he actually spent more time on theology than science BTW (kinda besides the point, but thought it was worth a mention).

For bonus points: If all the "rational thinkers" of the day had rejected Newton's contributions to science outright "for persisting in his sky fairy beliefs" would you say the church would be more or less power today as a result?

Surely any answer to that would be completely speculative...so pass.

So is manifest destiny, equality, self defense, protecting the poor, protecting the job creators, protecting jobs, protecting the environment, imminent domain, and many more.

I'm well aware of that, and I agree, but that doesn't negate that religiously motivated attacks, policies et.c are not a problem and need to be addressed, you know, shite like this a little lie from your doctor won't hurt you.

Another bonus question - which "evil" is more irrational?

 

1) The idea that just about any law abiding citizen has the right to own a gun, based on an anachronistic reactionary revolution-era constitutional amendment

2) The idea that a government has the right to decide whether average law abiding citizens have the right to bare arms

I've been gawping at this question for the last half hour, and I guess they're equally irrational, but I'm having a hard time trying to justify that (I'm very hungover BTW.)

If people are getting away with using religion as a tool for justifying irrational evils... just perhaps more rational people need to be involved in the dialogue*?

Yes, absolutely.

* again to be clear simply shouting "Sucks to your sky fairies!" does not constitute getting "involved" in the dialogue.

I dunno, you've got to start somewhere

Would you suggest that population is helped by knowing that there are others out there like me who "have their backs?"

Yes, I used to get a little annoyed when I saw examples of almost aggressive promotion of rational thought, say Hitchens and Dawkins et.c as it comes across as hypocritical. It's needed however, and judging by the state of politics in the US at the moment, i.e more extreme, right wing and religiously bolstered manifestos, it's needed more than ever.

Isaac Newton managed to be rational 6 days a week, go to church on Sundays, and still do more to advance every disciple of modern science on Sunday afternoons than most people (atheists alike) will contribute in a lifetime.

That's not a good example, the church had a lot more power back then, things (at least in the UK) have moved on somewhat.

So why can't we skip blaming the root of "religion" for all the irrational evils of the world and address the actual blatantly sick mentalities that are disturbing to most religious and non religious people alike?

Because religion is a tool for justifying irrational evils.

Though it is unlikely that such a thing would be fossilized after millions of years...

I actually have a coprolite, though I'm not sure what pooped it out. I'm sure there are plenty of examples that you could use to ascertain the average amount of dung produced by a large herbivore. It might be worth pointing out that dung was also a source of food for smaller dinosaurs. Here's an example of a sauropod coprolite...

So you have confidence in surveys where the survey takers filter out responses they don't like?

You really do need to back this up, and confirm there's a bias in the data for whatever reason.

iNow, I'm a bit confused by this thread, you've posted data that shows that acceptance of evolution is on the increase. What is interesting, is the shape of the graph concerning belief in a guided hand of evolution, verses a flat out denial of evolution is more or less constant. However the same sample seem to be changing their minds, i.e where there is an increase in one viewpoint, there's a decrease in another (or thereabouts), whereas the steady increase of acceptance of evolution doesn't follow this trend. I'm not sure what to make of this, but is it possible that science education in the US is actually working ?

Overlooking that the percentage who do accept evolution should be bigger, I'm not sure you're bringing anything new to the state of belief in the US. Considering if you're brought up in an environment where belief in god seems to be tantamount, and through fear, an individual can't be seen denouncing god (even through an impartial poll), I don't see that these results are surprising...but should be addressed nevertheless.

Personally I think the belief systems (with regards to religion) in the US are dangerous, and that such a prolific ignorance needs close attention...i.e I think a large population of the US are simply lying about their beliefs, and are following the herd through fear.

juangra, and questionposter, firstly, apologies for the rude post, it does nothing to bolster my arguments, and I really should know better than to post when I'm cranky. There's nothing worse than a hypocrite.

juangra, I guess we'll have to agree to disagree, that reality is solely described as particles. I only chose to vote waves and particles, because that's as far as my understanding takes me, and I realise it's far more complicated than that. I think the correct answer is that it is something more abstract, and I've already checked this elsewhere, with other people in the field (I guess you could argue that's an appeal to authority) but I feel they are trustworthy sources. I don't really wish to discuss the matter with you any further, thanks.

Regarding physics forums' date=' I kindly asked one moderator (in a personal message) to close the account. And I am considering to do the same here because it is a waste of time to debate with people who do not know the most elementary stuff but still pretend to be experts: Questionposter is an excellent example of this, but he is not the only.[/quote']

 

My bad, also remember you can use the ignore feature, if somebody is getting on your nerves. I hope I don't come across as somebody masquerading as an expert, I'm very careful to include my level of knowledge when I try to tackle more technical queries.

 

Moreover' date=' this is the second time that 'Royston uses ad hominem and insults against me. If my memory does not fail he was warned by a moderator in another forum.

 

Although I was warmly received when I joined the forum, I am seriously considering if I will continue here or not.

 

Regards.

[/quote']

 

I try very hard not to use logical fallacies in my posts, so if I did use an ad hominen, again my bad, but I don't recall this. Also, unless you're a member of my Uni forums, which I very much doubt, then this is the only forum I use. I am a member of the physics forums, but I've never posted on there, just a lurker.

 

Lets get back to discussing this very interesting subject.

blah, blah, blah

You've completed glossed over terms such as basic, and could be considered, there's only so much you can cover in a few sentences. I was setting the scene for a discussion. juangra, personally I couldn't care less what you think, you come across as an educated crank, and your attitude sucks. You've already been banned from the physics forums, and people like you make it hard for others to learn. I may get a mod warning for that, but it needed to be said. I've stuck you on my ignore list...along with questionposter, who ONCE AGAIN, has the temerity to lecture an expert with nonsensical drivel.

Sorry for the outburst, but I really wanted to have a decent discussion about the subject, not have it polluted with this guff.

Really quantum field theory is a theory of quantum fields not particles, which are rather a derived notion and quite a special one particular to "flat-like" space-times.

That's absolutely fascinating, thanks.

One of our tutors said pretty much the same thing, he then went on to use QED as an example, he had to keep it basic as we're studying an undergrad course. I guess quantum field theory can be reduced back down to more basic formalisms depending on the circumstances, analogous to the correspondence principle. So I guess the outcome of certain experiments can be viewed as a special case of QFT. I realise there are a number of quantum field theories, that seem to deal with particular problems, so I may be over simplifying here, but I'm hoping I'm on the right track.

Even more abstractly, one school of though is that the fields are not the primary objects, but rather the algebra of observables. This gets mathematically tough very quickly and the framework cannot cope with realistic theories.

Blimey, well I'll stick with basic QM for the time being, I'm actually just studying this out of interest i.e I have enough credits to obtain my degree already, but I'm absolutely hooked on the subject.

I'm going to vote waves and particles, because that's as far as my understanding goes for the time being (regardless of whether it's correct). It seems unfair to vote 'something more abstract', when I don't understand that level of physics.

This follows on from the thread 'what makes an electron orbit', but it's ten pages long (and counting) and gets a bit awry half way through. So I decided to start a new thread, and include a poll, where you can cast your vote, and include your reasoning to back it up. I've kept the description simple to just waves and particles, so it allows anyone to explain what they mean by (for instance) a particle.

Note, that I have not studied QFT, so I'll only provide a basic description from what I've been told, and then I'll provide a few examples to the whole wave-particle duality conundrum. It would be nice to hear a few expert opinions, as I know there's a few on here who have studied QFT. It would be doubly nice if they could provide some information, that could bridge the gap of understanding, for anyone who has not studied QFT.

Classically, a particle could generally be considered as a zero dimensional point, it can have properties such as mass, but point-like keeps the maths simple, and is ample for describing macroscopic behaviour.

In basic QM, the state of a system is described by a wave-function, which is the most complete description of that system. The wave function is not measurable, so is acted on by an operator, an observable is associated with that operator. The outcomes of the observable are dictated by it's eigenvalues. If the observable is position, then the act of measurement collapses the wave function, and what is detected is a particle. Taylor's diffraction experiment, or Young's double slit experiment, are good examples of this.

In basic QFT, (sticking to QED) particles can be considered as quantized excitations of a field. The number of particles are not fixed, and the use of operators (lowering and raising) create and destroy particles in that field. Applying QED to say a Mach Zehnder interferometer, still requires a wave and particle description.

The above definitions are probably far from perfect. However, some experiments still require a wave-particle duality interpretation, where as others do not, perhaps say a bubble chamber experiment. Are there more abstract definitions of a particle that could do away with the wave-particle interpretation in some experiments ?

Any corrections are welcome, but I'd be very interested to hear your thoughts on the matter (no pun intended).

Have a care with this statement.

 

What do you think the similarity of the classical oscillator equation is to the quantum wave equation?

 

Furthermore are you aware that an oscillator and a wave are different things?

He did say quantum oscillator, which is the analogue of a classical oscillator.

Not so much for your benefit, as you say you've studied QM however I'm happy to run through the derivation of this, but we'll be veering even more off topic. But classically (and restricting to simple harmonic motion) we have...

[math]V(x) = \frac{1}{2}Cx^2[/math] which is the potential energy of a simple harmonic oscillator.

[math]E_{kin} = \frac{1}{2}mv^2_x = \frac{p^2_x}{2m}[/math] which is the kinetic energy of the system, remembering that p = mv. So...

[math]E=\frac{p^2_x}{2m}+\frac{1}{2}Cx^2[/math] is the total energy of the system. C comes from Hooke's law i.e [math]F_x = -C_x[/math] that follows Newtons second law so [math]m\frac{d^2 x}{dt^2} = F_x = -C_x[/math]. This can be rearranged to [math]\frac{d^2_x}{dt^2} + w^2_0 x = 0[/math] where [math]w_o = \sqrt{\frac{C}{m}}[/math].

From here on it's simple to use the classical Hamiltonian function, and convert the variables to operators to construct the Schrodinger equation. If you follow through this derivation it should become clear how you get to this

[math]i\hbar \frac{\partial \Psi}{\partial t} = -\frac{\hbar^2}{2m}\frac{\partial^2\Psi}{\partial x^2} + \frac{1}{2} m w^2_0 x^2 \Psi(x,t)[/math]

This discussion doesn't seem to be getting anywhere, as you said, so I'll start a new thread and try to construct it in such a way that we have a more orderly discussion...because it is very interesting. I would also like to get some more insight on QFT (I've asked some experts elsewhere, so I hope my rudimentary understanding will be enough to kick things off properly.)

As an aside, Questionposter, a bit of friendly advice.

Please stop just grabbing tid bits of information and sticking them into discussions that are not related. It's if you're doing cursory glances at wikipedia, not bothering to understand what the terminology means, and whacking it into discussions. It's very frustrating for people trying to answer you're questions, because you're muddling things up and derailing threads, through people trying to explain to you what the terminology means, and why it's not related. Stick to short, succinct questions, understand the answer, then move on to something else, rather than jumbling stuff up. Sorry if that comes across as patronizing, that's not my intention.

juangra, I think it's high time you cough up, and state explicitly (rather than alluding to) what you mean by a non-classical particle. It is a very interesting debate, so I've done some asking around and, albeit wave functions are limited, and more modern treatments do not use them, I've been told the jury is still out, into how particles can be interpreted. IOW it is very abstract, and to palm off an interpretation as nonsense, just because a few text books use the word particle is a bit silly, no ?

Also, dropping the arrogance will do you some favours. You're making me suspicious.

While we're on the subject, I used to own some stick insects. My niece brought back some Peruphasma schultei (black beauty) nymphs from a school trip in London, see the photo on the left, of the last survivor. However, two of the nymphs, were not the same species (see photo on the right). They're fully grown in the pictures, but it was almost impossible to discern that they were different stick insects when they were nymphs.

You'll have to excuse the quality of the photo, but I was wondering if anyone could identify them. I've scoured the net and found one photo of these insects, but with no classification. The wing cases, although they never opened and I'm pretty sure they didn't have wings, are yellow (top set) and red (bottom set) with a mosaic pattern, similar to the black beauty wing casings. Yes, they're getting down to business, and the male is straddling the female. The female was roughly 7-8 cm, and the male 4-5 cm in length. So, any ideas ?

While I do have dogs that were passed down to me from previous owners, I also have a different type of relation with local animals, where they seem to rely on me occasionally for food and can come into my house without much trouble being caused, but are not a pet to anyone. Although, the alligator hasn't actually come into my house, but has been on my property, but it's more of a passive type, which is good. It's sort of fun having a bunch of animals around, there's often something different to see every two days.

The wildlife in the UK (overlooking marine and insects) is not particularly exciting, you'd be very hard pressed to come across anything dangerous, a disgruntled chaffinch perhaps...but no alligators. We have one venomous snake, the adder, but I've never seen one in the wild.

However, albeit not dangerous, we do get lizards in my local area, and the council have been very good, and have preserved their habitat. I'm like a kid in a candy store when they make an appearance.

...and 2 parrots, a Caique and an African Grey.

My sister owns three Harris Hawks, and I've been torn whether to bring up the 'keeping a bird in a cage' argument. She is training them to hunt. However, I've noticed, with her birds at least, they can sit perched for hours on end, with no desire to fly. I guess, I'm very ignorant to bird behaviour. So, is there a qualifying argument to keeping birds in captivity, beyond that animals in the wild spend their life in fear of being eaten, and trying to find food ?

I guess I find it hard that if one of the primary functions of an animal is taken away, such as flying, that it could be considered cruel. Again, I may be missing something, and this is in no way a judgement on the fact you keep birds in captivity. For all I know, your birds they have plenty of opportunities to fly around and do their thing...I guess I want to challenge my sister with some hard facts, or counter to that, know it's fine that she's keeping birds.

I didn't want to regurgitate an old thread, so I was wondering what pets SFN members had.

 

What prompted this thread, is that I'm now a proud owner of a coastal carpet python. I'm giving him a few days to settle into his new environment, before I start handling and feeding him, but he seems (based on his behaviour) very relaxed.

 

So, just wondering what pets you have, and if there's any reason why that particular animal / animals were chosen.

 

(Hints and tips would also be a plus )

BTW, if anyone has any pet mice or rats, I'm more than willing to look after them when you're on holidays

The typical answers for the shape of the universe are positive curvature, flat, and negative curvature. Is it possible that the curvature could be such that the entire universe is one closed timelike curve? One such that the Big Bang is caused by the Big Crunch? I'm not talking about a cylical model, but one where the end event and the beginning event are in fact the same event.

 

What would we need to look for to falsify this idea?

I actually asked the same question when I studied cosmology a couple of years back. I'm pretty sure CMBA (cosmic microwave background anisotropies) rule this out, due to not agreeing with (as elfmotat stated) rotational models. They don't fit CMB data. It maybe worth looking into Bianchi cosmological models, as further rotational models have been built from these, IIRC Hawking proposed a rotational model built on one of the many Bianchi classifications. This is from memory, so I'll dig up some links.

This is very high end cosmology though, and probably won't make sense unless you have an understanding of Lie algebra. Point being, there have been more advanced models after the Godel metric, but I'm pretty sure they've been rejected.

EDIT: I think I should have mentioned I don't understand Lie algebra...I've only studied and understood basic solutions to GR

I didn't want to regurgitate an old thread, so I was wondering what pets SFN members had.

What prompted this thread, is that I'm now a proud owner of a coastal carpet python. I'm giving him a few days to settle into his new environment, before I start handling and feeding him, but he seems (based on his behaviour) very relaxed.

So, just wondering what pets you have, and if there's any reason why that particular animal / animals were chosen.

(Hints and tips would also be a plus )

Eh ? Having an innate ability in a field, means a subject comes easily to a person. Another example, is art (say, illustration) which is also a man made concept. It's perfectly obvious that some people have a natural gift when it comes to drawing, over others, the same with dealing with numbers and logic.

There is little evidence to suggest that there these are innate abilities. In contrast, many young geniuses spend an extraordinary time into their talent. You will note that talented artists have spent an enormous amount of time to become talented. There are basic capacities that have a biological basis that will strongly affect or the outcome (such as a good memory, good senses, etc.). However, complex traits (artistic abilities, reasoning abilities) cannot easily be reduced to a simple basis are therefore much more dependent on training (and hence, interest). Again, if you simply do not like playing the piano, you can slog through hours without improving skills. If you are a Mozart, you will go through the same thousand of hours, with much more focus and learn from it.

I've been very busy the last few days, hence the late reply.

That was a pretty poor post on my part, (sorry I was in a rush) and should have clarified my point. What I meant by, a subject coming easily or more precisely easier to a person, doesn't mean a complex trait is innate, but that certain core attributes e.g memory or information processing can be the foundation for somebody finding a certain subject easier. There's obviously a difference between a subject coming easier, and already having the skills to perform more complex tasks e.g such as drawing. I personally see certain core attributes as a gift (for want of a better word), and they manifest into a talent.

I mainly had a problem with purephysics suggestion, that if a concept or subject is man made, then there are no hard wired (i.e hereditary) mental attributes, that would make somebody excel over another (given they're both very interested in the same subject).

because math is a man made concept, therefore it is not something anyone is born with the ability to do.

Eh ? Having an innate ability in a field, means a subject comes easily to a person. Another example, is art (say, illustration) which is also a man made concept. It's perfectly obvious that some people have a natural gift when it comes to drawing, over others, the same with dealing with numbers and logic.

i guess the main worry id say i have is the math, it really isnt my strong point :-/

My advice is to practice, practice, practice and practice some more, before you start your degree. Better yet, enrol in an applied maths course before you start, that covers calculus, vectors, and probability. I studied a general science course (biology, chemistry, and physics) and two maths courses before I embarked on my degree, due to such a large gap in my education. There's no point in starting if you're not sufficiently prepared, plus it will give you a taste to see if you really enjoy it.

EDIT: Also you can see if you have the necessary skills required, as timo explained.