* Posts by the small snake

265 posts • joined 13 Aug 2021

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NASA: Mars rocks won't make it back to Earth until 2033

the small snake Bronze badge
Boffin

Re: Unnecessary complexity

If Perseverance carries the samples then if it fails you need something that can get to where it is to retrieve them. Worse: if it gets stuck somewhere where it is clear other rovers will also become stuck then samples are effectively lost.

If none of this happens you are merely left with requirement that Perseverance must both be able to return to wherever the sample return vehicle lands, and be able to unload samples. Both of these, particularly first one, will limit what you can do with Perseverance mission, which is undesirable.

Is the $10 billion James Webb Space Telescope worth the price tag?

the small snake Bronze badge
Boffin

Re: Total waste of money... yes, it is.

Well now. If you know all the things you say, then you would not have said 'Lets see a side by side comparison of the Webb imaging with the current best earth based telescopes', would you? Because you would have understood that such a thing is not possible. Unless you are a different coward but I think you are not.

But you did say that.

And if you were as clever as you think you are you would also have noticed that I did not claim JWST was worth $10E9 and indeed in other comments I have said that probably that it is not (but that in recent history it should not have been cancelled for a sort of inverse version of Concorde fallacy). Certainly it is extremely dear compared with ground-based telescopes (I believe VLT was about 1/10 price).

And finally you would not have made this really very stupid comment:

Yeah, sure having a mongo IR mirror in space is nice for the very small number of IR researchers (its not a big field) [...]

I mean, that is really an impressively dumb thing to say. How many gravitational wave astronomers were there ten years ago? How many are there now? How many radio astronomers were there before 1933? How many X-ray astronomers before 1958? Here is thing: if no instruments for a certain type of astronomy exist then the number of astronomers working in that field will be very small, and that tells you nothing at all except that instruments do not exist.

I am sure you are not a stupid. But your comments are stupid. Probably that is why you make them anonymous of course. Well, I am done replying to stupid comments: is entertaining to make fun of them but not so entertaining.

the small snake Bronze badge
Boffin

Re: Total waste of money...

Lets see a side by side comparison of the Webb imaging with the current best earth based telescopes.Like the LBT or GTC. I know the Hubble did not hold up too well against Keck I let alone Keck II. Or even compare Webb imagery with some of the other 6m telescopes for that matter. (Not BTA-6..).

Sadly that is not possible. Is not possible,because the Earth has inconvenient atmosphere with inconvenient water vapour etc which is opaque to most infrared. If you want to make a good IR telescope you put it above the atmosphere, and preferably at L2. That's why Herschel was at L2, and why JWST is at L2. The things that Herschel did and the things that JWST is doing can only be done in space and really can only be done somewhere like L2 (or perhaps in permanently shadowed parts of Moon as someone said).

JWST is not a super-Hubble: it is a different thing. As I said in other comment, probably there will never be a super-Hubble because visible-light telescopes can work well on the ground: IR telescopes can not.

the small snake Bronze badge
Boffin

Question unclear

Should JWST have cost what it did? No, not nearly as much.

Was there a point, early in project, when it should have been abandoned in favour of cheaper alternative? Probably yes, with hindsight.

Was there a point recently (say last five-ten years?) when it would have been better to write off JWST? No.

Given what JWST cost, would this money have been better spent on ground-based telescopes? Not answerable: JWST is very much money – I think VLT cost was approx 1/10 of JWST so could have built really large number of really large ground-based telescopes (VLT is four 8.2m telescopes, four 1.8m telescopes, is usable as interferometer with really enormous baseline). But no ground-based telescope can do what JWST can do.

Will there be more big visible-light space telescopes? I bet not: ground-based things are now so good we do not need a super-Hubble I think.

Is what it cost a lot of money compared to what idiot politicians waste on stupid schemes? No: if you want to get more money for good causes do so by sticking sharp things up rear end of idiot politicians, not by taking relatively tiny money from science projects which make being alive mean something.

Mars helicopter to take a breather, recharge batteries

the small snake Bronze badge
Boffin

Try to think. Adding another panel would double the mass of the panels, and double the effect of the panels on the airflow over the blades thus making the blades less efficient meaning it needed more power to fly, some combination of bigger batteries (more mass) or shorter flights.

The thing was meant to fly three times. It has now flown twenty-nine times: almost ten times as many flights as it was built for. And it is not dead yet.

the small snake Bronze badge
Alien

Re: Nothing there....

Ah, poor Zanzibar, your life must be so empty with no sense of wonder or curiosity. Of course you will say it is not empty, because, lacking any sense of wonder or curiosity, you can not know what you lack.

But you suspect, do you not? And it burns at you, and you hate the people who are not damaged like you, the people who do have curiosity, the people who do have wonder and seek understanding of new things. So you spend your time searching out posts about exploration and curiosity and wonder and trying to spread a little of your grey depressing emptiness: trying to make everything a little worse. And you succeed: you do make everything a little worse, a little greyer, a little more empty. Well done.

I see you have turned up on threads about JWST images now as well, posting your idiocies. Ah well.

the small snake Bronze badge
Boffin

Ah yes, And all the people who have worked for years on this did not work this out. Clever you.

Hint: dry dust, small dust, dry atmosphere, static electricity.

James Webb Space Telescope looks closer to home with Jupiter snaps

the small snake Bronze badge
Boffin

Re: Wait till the press tour is over.

Certainly I think resolution will be lower than spacecraft close to planets (for instance Juno), simply due to physics of telescopes. But this is not what they are for: JWST can observe at wavelengths which have not previously been possible and so will give us information we previously could not have: certainly not from ground-based telescope and to date not from spacecraft near planets either.

First-ever James Webb Space Telescope image revealed

the small snake Bronze badge
Boffin

Re: Larger still

Yes, all of physics is mathematical model.

But if you can establish a finite (no need for infinitesimals or any non standard number system) lower bound for the probability of life in some volume, or equivalently a finite lower bound for the probability density over some spacelike surface, then in an infinite homogeneous universe (so assuming flatness, no weird global topology, cosmological principle, all as I said earlier) then probability of life is 1. Not 'approximately 1', 1.

And it is easy to establish such a finite lower bound in fact: simply compute the probability of life spontaneously arising due to quantum effects (this is related to Boltzmann brain idea). This is very small but it is finite. Real bound will presumably be far higher but we do not need it: we can just use this one.

I am done here now as it seems increasingly you are arguing from some weird philosophical position and I have no time for those, at all. I am scientist (well, mathematician) I do science not silly word games.

the small snake Bronze badge
Boffin

Re: Larger still

enganglement does nothing for causality.

the small snake Bronze badge
Boffin

Re: Larger still

Am very aware that infinite sums can be finite: am mathematician. Indeed this is one such case: divide universe into hubble volumes, chance of life in each is c, chance in n is infinite number of hubble volumes ... chance is 1, unless c is 0 which we know it is not.

what you are missing is homogeneity (one of implications of cosmological principle). All these volumes are the same, have the same laws of physics same amount of matter. You keep throwing the dice of arrangements of that matter you will get life with nonzero probability in each one.

yes cosmological principle is principle ie assumption. So is flatness (rather than just approximate flatness), then spatial infiniteness and blah. But given those assumptions probability is in fact 1. See comments by Michael Wojcik who goes into some detail.

(Of course most of it will be causally disconnected from us, and none of this means we should decide Earth does not matter.)

the small snake Bronze badge
Alien

Re: An honest, possibly dumb question

It was about $10 billion. This was too much and much more than it should have been.

During 2020-2021 the UK government wrote off (which means 'threw away' I think) £8.7 billion on PPE they could not use.

OK picking UK government as comparison is unfair as they are both very dim and very corrupt, but $10 billion is not so much.

the small snake Bronze badge
Boffin

Yes you could do that I think, at the cost of halving the useful telescope time.

However it is important that those spikes are very very dim: if you are looking at some object then in order to see those spikes show up at all the object would be vastly over exposed. In the image for this article every object has these spikes around it, but you can only see the ones from the vastly overexposed foreground stars.

Indeed is possible to see from this image how dim these spikes really are: if you start from the very spiky star just to left and up from centre of image, now look at vertical spike from it. A little way up it crosses a red galaxy, which clearly brighter than the spike at that point. That galaxy is red, so it is presumably a member of the background field not the closer-to-us galaxy cluster. Perhaps it is 10bn ly away or more I do not know. But it appears comfortably brighter than the spike.

If JWST was to take a useful image of the foreground star which is making the spikes then they would not even be visible.

the small snake Bronze badge
Boffin

Re: Can someone smarter than me...

OK. If JWST operates at 1000nm (near IR, this image is near IR) and has mirror 6.5m its angular resolution limit is about 1.8E-7 radian. So we can ask: how far would it have to move for the parallax between two objects it is looking at, one of which is 4.6E9ly and the other is about 13E9ly away to change by this amount? Is quite easy to calculate this: l = 1.8E-7(1/d1 - 1/d2)^-1 where d1, d2 are the two distances.

Answer is ... about 1300ly. or about 10 million times orbital radius of Earth, or about 330 times distance to nearest star. But a bit less than 5% of the way to centre of our galaxy, so not that far, really.

So parallax is not a problem here.

Also optically it is all 'at infinity': for the same reason you do not need to refocus your camera when taking a picture of something on km away and something two km away you do not need to refocus a telescope when taking a picture of something 4.6 billion ly away and something 13 billion ly away.

the small snake Bronze badge
Boffin

Re: if the dark matter theory is right

I'm no physicist, but I know that Einstein already took us beyond Newtonian physics.

However in these regimes GR and Newton gravity should agree extremely closely, so if MOND is true (I think it is not) GR is also falsified.

the small snake Bronze badge
Boffin

Re: Larger still

Oh yes agree with that. But if universe is spatially infinite, then probability is not just very close to 1: it is 1.

the small snake Bronze badge
Boffin

No, and it will not do so. The spikes come from three things: the overall shape of the mirror, the edges of the mirror segments and the struts which hold the secondary mirror.

The first two you cannot do without (the design of the struts is chosen so that their spikes overlap with those from the mirror segments).

The last one you cannot do without if you wish to have a mirror which contains individually adjustable segments, or which can be folded up for launch. You could by building really enormous spacecraft deal with the second, but you still need the first for very large mirrors.

Note that the spikes are extremely dim compared to the image: the reason they appear so bright in this image is that there are foreground stars which are extremely bright compared to the objects of interest in the image which are therefore grossly overexposed in this very long exposure.

the small snake Bronze badge
Boffin

Re: Can someone smarter than me...

Do not be silly: do you realize just how far the telescope would need to move to make an effect like that even detectable?

the small snake Bronze badge
Boffin

Re: Can someone smarter than me...

This is gravitational lensing. The light from these distant galaxies has passed large massive objects (galaxies in the foreground cluster) and has thus 'changed direction' (really: it has travelled in a 'straight line' (geodesic) through spacetime which is curved by these massive objects), which gives rise to this distorted appearance.

the small snake Bronze badge
Boffin

Re: if the dark matter theory is right

That is least convincing article I have ever read. Well no it is not, but it is very unconvincing. In particular notice the littly tiny caption on their second table:

Similar to Figure 1, but for Mond with hypothetical particles that only interact via gravity called sterile neutrinos. Notice the lack of clear falsifications.

Wait, wait: MOND with hypothetical particles that only interact via gravity called sterile neutrinos. Right yes, I see, so you patch up MOND to make it work with particles which only interact gravitationally, but which we cannot otherwise detect. Yes, yes, we could perhaps give those particles a name, could we not? Something like, I don't know, 'dark stuff'? 'invisible matter'? 'invisible stuff'? Hmm, hmm, yes.

the small snake Bronze badge
Boffin

Re: Correction or have I misunderstood...?

At that distance the Earth does not eclipse the Sun completely so some of the Sun is always visible. However JWST orbits around L2 so Sun is likely never shaded for it.

Reason for L2 in fact is that Earth and Sun are both in approx same direction so you can put heat shield up and protect against heat from both the large objects at the same time (also Moon I expect). Anywhere else you either need to be too far from Earth which lowers bandwidth or you need two shields. So L2 is brilliant for this.

the small snake Bronze badge
Boffin

Re: Larger still

As other commenter said, on current assumptions chance of life elsewhere in universe is 100%. 'Other assumptions' are here that universe is spatially flat, not topologically strange on large scales and therefore infinite, and also that is homogeneous on large scales.

Behold: The first images snapped by the James Webb Space Telescope

the small snake Bronze badge
Pirate

Re: Remember when?

Is in fact strong argument that JWST should have been cancelled. It was so far over budget that it was likely at various times clean start would have been cheaper.

Not that it is not amazing, but perhaps two of three 2-billion dollar JWSTs would be more amazing.

the small snake Bronze badge
Boffin

Oh no this is not true. See for instance HR 8799: direct image of a system with at least four planets. The movie is amazing.

the small snake Bronze badge
Alien

Re: Planetary pedantry

Is funny you get downvoted for stating what any linguist would say was obvious. Prescriptive language people really get everywhere sadly. Like lice.

the small snake Bronze badge
Boffin

We can see a planet 1000 light years away in that detail?

We cannot. The background of that image is not the planet or the star (and is rather confusing).

JWST resolution limit is about 1.9E-7 radians at 1000nm wavelength. At 1000ly WASP-96 (the star) would subtend about 7E-11 radians so is hopelessly unresolvable. WASP-96b is much smaller. Indeed if orrbital radius from Wikipidia (0.045au) is correct, is not possible for JWST to resolve planet as separate from star even (this is about 7E-10 radians).

This is not what they are doing however: WASP-99b moves across its star as seen by us, so what we do is watch the star as it does so: the light from the star is (slightly) blocked by the planet, and some of the light also passes through the atmosphere of the planet so the spectrum of the light that reaches us changes slightly. From these changes in the spectrum we can conclude things about the atmosphere of the planet. Particularly significant is evidence for clouds which WASP-96b was formerly thought not to have.

Soviet-era tech could change the geothermal industry

the small snake Bronze badge
Pirate

Re: what if ...

You'd better have a fire crew standing by for dealing with misses as well, because things like trees, plants, and houses are much better absorbers of microwaves than metals.

Do not aim at the metal thing, is wast of time: aim at the ground around it. Tank does not work well travelling through boiling rock. Works even less well when rock solidifies. Also probably rock will boil explosively.

Big Tech silent on data privacy in post-Roe America

the small snake Bronze badge
Alien

Re: Democracy

Do you believe that the framers of the constitution wanted to include the right to those things? I don't.

Yes, this is the funny thing. Several of the people who wrote the constitution owned slaves. Perhaps some of them thought that black people were people but am sure none of them thought that they should be treated equally as white people. Very unlikely any of them thought that women should be treated equally to men.

Who would care what these people thought other than for historical interest?

Imagine if physics was done this way. We would have committees which sat trying to pore through the writings of Newton and insist that the laws of physics must be as he wrote them. Occasionally rulings would be put forth making General Relativity or Quantum Mechanics illegal.

Increasingly seems that problem is that human beings are simply too stupid to survive.

the small snake Bronze badge
Alien

Re: Democracy

If you actually had ever spoken to a woman would know that very many women are not lucky enough to have completely regular menstrual cycles. Two regular cycles is approximately 8 weeks so it is trivial that many women do not know they are pregnant until more than 6 weeks have elapsed.

Whatever hit the Moon in March, it left this weird double crater

the small snake Bronze badge
Boffin

Yes. Were no craters 28 Feb, were two 21 May

the small snake Bronze badge
Boffin

Re: Bouncy space junk?

This is interesting possibility. I tried to find estimates of impact rate but could not find anything simple. Good place to start seems to be NASA Lunar Impact Monitoring Program and then perhaps NELIOTA Project: first seems not to have publications yet but second does (but I did not read it).

My uninformed guess then is that impact rate is so low that chance of two unrelated impacts in 82 day period (between Feb 28 2022, May 21 2022) causing overlapping crater is within epsilon of zero.

Cookie consent crumbles under fresh UK data law proposals

the small snake Bronze badge
Boffin

Re: Straightforward solution

So how do you think the browser is telling the server that you are logged in next time you go there? By magic?

No, it is not by magic: it is by sending a little bit of data which the server looks at and says 'oh, that is that nice coward person again, they have authenticated themselves with me, I need not ask them again'. You can call this little piece of data and elephant, or a fish if you like, but what it is is state.

SpaceX reportedly fires staffers behind open letter criticising Elon Musk

the small snake Bronze badge
Pirate

Re: Unclear on this whole employment thing

pfft. Musk is a rich: rules are not for the rich, they are for peons.

the small snake Bronze badge
Alien

Re: Careful what you ask for

It suggests that if SpaceX does not explicitly state that, for example, murder is unacceptable, then (according to the letter writers) SpaceX implicitly endorses murder.

'Clause 9: Things which are illegal are not acceptable.'

Not so hard eh.

SpaceX staff condemn Musk's behavior in open letter

the small snake Bronze badge
Alien

Re: This is what late stage Elon looks like

I see the muskovites (perhaps those ones too) hate you: is generally a good sign when they do. But if was me I would worry Musk has amphetamine psychosis or something similar to that. Know nothing about his drug habits if any but it smells like that (and I have first-hand experience of this). If it is this is as you say very sad and he should get treatment.

Your 'techbro bat' comment is just stupid: the techbros are very pro Musk he is their now tinfoil god.

Meteoroid hits main mirror on James Webb Space Telescope

the small snake Bronze badge
Boffin

Re: How are impacts detected?

Given they do not know the exact time of impact ('between May 23 and 25') is presumable not direct detection of event but perhaps discovery that mirror segment is now not aligned suddenly or is slightly deformed and needs adjusted.

the small snake Bronze badge
Boffin

Re: Would something like an temporary protective bubble help?

Answer is simple: if it is survivable you can neither see it in time nor predict it, and by far your best chance is to allow it to pass through your structure so it does not deposit its kinetic energy in it (a 1g object travelling at 20km/s (seems to be average speed for micrometeoroids) has KE equivalent to about 47g of TNT which is about half a hand-grenade I think).

If it is not survivable then perhaps you can see it in time but ... it's not survivable: a 1kg object at 20km/s has KE equivalent to about 47kg of TNT, and you are not flying a shield which can defend against an impact like that). Even in this case your best hope, by far, would be to hope it just makes a hole but probably any such impact would destroy the telescope.

You could certainly fly several telescopes for the cost of defending one and that would be by far the best approach.

the small snake Bronze badge
Boffin

Re: Would something like an temporary protective bubble help?

Let us assume your shell can be deployed in 1 second (using no more than solar power and not completely destroying the alignment of the telescope due to vibration, so this is pure fantasy). These objects are travelling at upwards of 10km/s and perhaps are 1mm across. So you must detect it 10km out. You will need a telescope to do this, which we assume will use visible light, say 500nm wavelength.

So Rayleigh criterion: we need to be able to resolve this thing. theta = (1/1000m)/10000m = 1E-7. lambda = 500E-9m. D = 1.22 lambda / theta which is approx 5m. So to see this thing you will need a telescope with a 5m mirror working in visible light.

JWST main mirror is 6.5m so this telescope is smaller ... a bit. Oh but you must cover the whole sky with this: you will need many of them pointing in all directions. Let us say 6?

But of course you will need multiple observations to estimate trajectory. And spotting it 10km out is hopelessly later than you must really spot it, perhaps you really need 100-1000km away. So say 100km now D = 50m. Perhaps you could work in UV make it a bit less? Say 25m dishes, 6 of them.

Think of the kind of missile detection and tracking systems warships have, but the objects you wish to track are travelling at mach 30-100 or more, are the size of rice grains or smaller and have no convenient hot exhaust. And they can come from any direction in the full sphere. And the system must run from solar panels, must run cold to not disturb the telescope, must emit no vibration and have no real moving parts (momentum, angular momentum) and can not emit any kind of exhaust or anything which might land on the mirror or optics.

Yes this is not even slightly possible

the small snake Bronze badge
Boffin

Re: Disappointing

Such a shield would have to be both transparent at all wavelengths the telescope operates at, manufactured to as high a tolerance as the mirror is (no point in using cheap crap UV filter in front of your expensive Leica lens for instance), and strong enough to not simply fail and spit vapourised shield meteoroid as well as fragments of both at the mirror. Also, after it has done all that magic, it must not end up covered in opaque marks, or deformed in any way.

Probably (certainly) better just to let the object hit the mirror.

NASA's InSight doomed as Mars dust coats solar panels

the small snake Bronze badge
Alien

Re: Insight?

Because I am annoyed by people who think that they know better than my friends who actually do these things and that insulting them is fine. All while very clearly knowing nothing. If that annoys you then ... good.

(No I do not do these things, am theorist, do not work for any space people. Just know people who do.)

the small snake Bronze badge
Terminator

Re: Insight?

Not he

the small snake Bronze badge
Alien

Re: Insight?

NASA seems to have given up on the 'try it and see' approach

You may have heard there is a helicopter on Mars which shows that this is as stupid a statement as sounds it is. There is also a (failed) digging experiment attached to something called Mars InSight I believe: try it and see, sometimes it fails.

but in something like this the worst that could happen is that it just doesn't work.

Oh do not be so fucking stupid: the worst that could happen is that something goes wrong with all this added complexity which kills the spacecraft before or shortly after it gets to Mars. Perhaps you have heard of Schiaparelli? Something went wrong with it which killed it. Perhaps you have even heard of Beagle 2? Something went wrong with it which killed it. That something was to do with the deployment of the solar panels, very likely.

Perhaps like me you watched JWST disappear from top of Ariane and saw the panels deploy and knew that now there was at least a chance it would work: Solar panels are critical to these missions: if their deployment fails then the mission is dead: is a total and immediate loss. If you are flying such a mission you do nothing which even might hinder deployment of panels. Not cleaning them might limit mission life; a fancy cleaning system which breaks deployment kills the mission.

Perhaps also you have heard of very famous quote:

Mars Is Hard

That quote turns out to be true and it means that people who want to land things on Mars are extremely careful to add nothing which might kill the mission. Anything involved with the solar panels might kill the mission.

And finally you guys with your half-formed ideas are just really funny: do you really think mars people have not thought of these things? Because there is wonderful thing called search engine, and if you search NASA Tech Reports Server you will find ... 921 hits for 'dust solar panels cleaning mars'. Turns out they have thought of many, many things. The people who worked out you could land a thing the size of a car on Mars using a crane turn out to have thought of other things too. Quite a lot of other things.

the small snake Bronze badge
Alien

Re: Insight?

So, it just never occurred to anyone on the development team that dust accumulation on the solar panels could be a problem?

Perhaps since many other spacecraft on Mars have died because their solar panels got too dusty it did occur to them, yes. Because perhaps people who design spacecraft are not stupid people you see, and they have also landed other spacecrafts on Mars and they know how this works.

And perhaps they worked out that, because the solar panels are very large (2.2m diameter, 2 of them), because moving parts (large moving parts) add mass and complexity and risk, because moving parts cost power if you ever move them, because scraping abrasive dust across the panels is likely to make things worse not better, because in any case the dust is attached to the panels by electrostatic forces as environment is extremely dry (and no, can't just take squeegee bottle and pour water all over pristine environment and spacecraft) so probably would not come off anyway, and and and ... perhaps they worked out that this was not realistically possible.

So they accepted that of planned mission of 709 sols they might have to live with, maybe, 1400 sols or so (currently at 1235 sols). Perhaps a mission double the planned length might be counted as a success, don't you think?

What am I missing here?

What you are missing here is that you are not even smart enough to realise that people who design spacecraft which land on Mars are both extremely smart and extremely experienced at the problems of landing and maintaining robotic spacecraft on Mars.

Pictured: Sagittarius A*, the supermassive black hole at the center of the Milky Way

the small snake Bronze badge
Boffin

Re: Design Flaw

Working out the mass does not help: you must change either distribution of mass, or how gravity behaves with distance. Many people have worked hard on the second idea with not much success. The first idea has a name and that name is 'dark matter'.

'Dark energy' from GR point of view is just nonzero cosmological constant. Not clear why for 80 years everyone assumed it must be zero since is free parameter of theory which needs to be decided by experiment. We have now done experiments and found it is not zero.

the small snake Bronze badge
Boffin

Re: Design Flaw

if you assume light dissipates its energy as it travels, then you get a red-shift

Just one more spear in this cranky idiocy. You do not get a red shift if you assume that. This is easy to understand even for crank I think. Consider two people: one is standing near star, and she is counting the waves as they pass her. Another is standing far far away and counting the waves from the star as they pass her. And spacetime is nice and flat and not expanding or anything. First person counts certain number of waves per second. Other person counts number of waves per second. If this rate of waves passing is different – if the frequency of the light entering the volume of space between them is different – then waves must be building up in this volume of space, which cannot happen.

This does not happen for other waves: for sound for instance. If I talk to you though a thick wad of sound-absorbing material then my voice becomes faint: it does not become deep (different frequencies may be absorbed differently but individual frequencies are not changed).

It also does not happen for light as we can easily experimentally test and as we test every minute of every day. Shine a laser through a long length of fibre-optic cable: what comes out at the other end is same frequency, but very very dim.

But that is not what happens with distant stars, at all. We can look at things in distant stars which we know have very well-defined frequencies which we know what they are: spectral lines. And we see those lines are shifted to the red: they appear to have lower frequency. That means, that these stars must be receding from us.

the small snake Bronze badge
Boffin

Re: The great flash

The observation is that the energy density of waves gets weaker as they spread out. Maybe "dissipate" is not the right word for this, as it implies energy being lost.

May have noticed that this happens for light as well. SN1987Avisible with naked eye I think (apparent magnitude 3) but you could stare at it for long time, no trouble.

Yes SN1987A was quite bright. Is famous quote: which is brighter: SN1987A viewed from radius of Earth's orbit, or hydrogen bomb pressed against your eyeball? Answer: SN1987A is brighter ... by a factor of about a billion.

Yet when we looked at it it was quite dim ... because it was far away.

the small snake Bronze badge
Boffin

Re: Design Flaw

Obvs you are crank, but can't resist...

Given proper length of path of light ray is zero how is it you think light loses energy?

Climate model code is so outdated, MIT starts from scratch

the small snake Bronze badge
Boffin

Re: Taking the average

Milankovitch cycles are not changing the orbital radius: they are changes in orbital eccentricity, axial obliquity and axial precession. Orbital eccentricity changes are due largely to Jupiter but also Saturn. These cycles are pretty well understood over short (few million years) times thoigj there is probably chaos in longer (billion) year times. End result of these is change in northern hemisphere (where most of the land is) insolation which drives climate change.

Is funny that you thought it was changes in radius: either you can't read wiki page or you are lying, or both of course.

Also everyone knows solar luminosity changes (in fact models of stellar evolution are things I have worked on though for early universe) and it would be extraordinary if such changes had not driven climate change. We know for instance that luminosity has increased very significantly over time: by factor of at least 5/4 in last 3 billion years for instance, and early-dim-sun is a problem people worry about I believe. And there will be shorter term variations no doubt. We also know that solar luminosity change since say 1950 is nowhere near enough to drive observed climate change since then, because we have good measurements of both things. That is what the IPCC section that you are lying about (or more likely you did not manage to read it) says.

So please: stop lying. And now I really will stop: arguing with liars and idiots is a waste of my time.

the small snake Bronze badge
Boffin

Re: Taking the average

Hydrogen has a lifetime in the atmosphere of one to two years and any hydrogen leaked into the atmosphere means you are wasting it. CO2 has atmospheric lifetime of hundreds of years and is an inevitable consequence of burning carbon. These two things are not the same.

And yes it is expected that CO2 level changes would probably lag temperature in ice cores since these changes were not driven by large emissions of CO2 but rather by various factors of which most significantly Milankovitch cycles (orbital changes). CO2 concentration and climate are in fact correlated: either can drive the other. For recent glaciation cycles there was no huge civilisation puking out CO2 so we expect (and see) a lag. Now there is and it is leading climate.

Ah well there is never any purpose arguing with denialists like you is there: it is like arguing with mud. I will not reply further.

the small snake Bronze badge
Boffin

Re: I just have to LAUGH at the level of cluelessness here...

I know it is hard to understand esp when you don't want to. Climate is the long term average of weather. This means individual weather events ('it is hot today', 'there is a big storm') are not climate, but the long-term averages of them are. As climate changes both the probabilities of certain events and the actual values of various characteristics of those events will change.

It is sometimes (but not always) possible to ascribe individual events or their characteristics to changes in climate with good probability. As modelling and understanding improves this becomes easier but it is very seldom certain. Example might be long hot dry (or long cold wet) spells in mid northern latitudes: because climate warms far more in arctic than at equator this means jet stream slows (less angular momentum to shed) which means it will become much more wiggly and this can result in these long trapped weather patterns. So would expect these to become more common and it seems they are. But it is still questionable to say that individual events are due to climate: their statistics are, certainly.

Is easier to ascribe things which are directly sensitive to these averages, for instance plant growth. Is very well attested that growing season in UK is far longer that it was even in recent history for instance.

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