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Gigantic Chinese telescope opens to astronomers worldwide (nature.com)
231 points by bookofjoe 19 days ago | hide | past | web | favorite | 123 comments

There's a cool 360 image -- https://goo.gl/maps/v4VkHhGmp5mfFk457 -- from the (near) center of the telescope.

Do you think that mesh is tight enough to skateboard on it?

Great image, but i expected a clear sky.

Buying or opening a new telescope is known to all astronomers to cause cloudy nights for weeks.

The sky is clear enough for a radio telescope to work fine. (Unless you try to go to VERY high frequencies, i.e. double digit gigahertz.)

Arguably the fact it's daytime is a larger problem for that sort of observations.

Previous record holder was the well-known Arecibo telescope at 305m diameter:


500m may not seem like a huge improvement over that but here's a picture that puts it in perspective:


Lost in the announcement is the fact that they're opening this for global research because... they don't really have anything queued up yet. High-aperture radio astronomy doesn't really have a hook right now.

Arecibo was built half a century ago now, and ever since has remained (by far) the most sensitive radio telescope available. Yet... it hasn't found much that we didn't already know about. FAST seems likely to sit in the same realm: it'll be able to see known phenomenon farther away, but that's about it.

We have plenty of radio sensitivity right now, what we need is broader coverage to pick up transient things like FRB's, and (as always) longer baselines for VLBI work (e.g. the Event Horizon "Telescope"), both of which which mean more dishes, not one giant dish.

I think this is a bit unfair: better point sensitivity has obvious scientific value, it just isn’t the most cost effective radio project if you have expertise in building arrays already.

And those extragalactic pulsar studies they hope to do sound pretty nice.

Is there anything preventing them from tuning up FAST so it's as or even more sensitive than Arecibo? Like, is it just a matter of better sensors or dish design? Maybe we don't need it, but cleaner data would be nice at least.

FAST will surely be better than Arecibo, absent some kind of terrible technical glitch. The point was more that, post-Arecibo (and again we're talking the 1970's here) there has been no rush to build more Arecibo-style dishes, because the perceived scientific benefit is low.

I see. Curious they just spent a big wad of cash on it, though I suppose they've been doing lots of construction work with marginal utility.

It is more sensitive than arecibo already.

Sorry, I couldn't help myself.

Real missed opportunity there to name it the Five-hundred-meter Aperture Radio Telescope. Bonus points if they detect an interesting pulsating signal and do as was done with the gravitational waves, shifting it into the audio band...

I'm hopeful that the scientific community will be happy to colloquially refer to this as the FARTiscope

”The 1.2-billion-yuan (US$171-million) telescope,”

This price is surprisingly low compared to other big science projects.

Seriously low. I'm impressed. Also it said in the article it only took half a decade to build, which is also pretty impressive for such a large instrument.

I wonder whether this is because they don't need to have a highly specified lens found in conventional telescopes?

Not sure why you're being downvoted.

This is correct to an extent, the surface of a mirror needs to be polished to a degree such that abnormalities in the lens are small relative to the wavelength being observed (I think it's the diffraction limit equation, not positive atm). Radio telescopes (with cm wavelengths) require much less precision than optical ones (with sub-micron wavelengths). This telescope, FAST, actually is made out of a collection of triangular (I think) sheets arranged into a kind of dome, if it were observing optical it would act like a disco-ball instead of a parabolic mirror. Arecibo is literally a hole in the ground with rocks and crap on the reflector.

This thing actually had "first light" observations with several holes in it from triangular sections that were fritzing just kind of fluttering in the breeze. The first radio telescopes were literally built out of post-coldwar trash just kind of rigged up in the back-yard. There's a major array going in in south Africa where the antennas are like christmas tree wires that are just kind of hammered into the ground, one of the PIs showed video at a colloquium I attended of his 10 year old kids setting them up. If anything in modern science can be called "low specification" it's radio telescopes.

it’s a radio telescope...

Labor costs are much lower?

Somewhat, though it's also a lot easier to build large radio telescopes because they're mostly a giant metal structure which is less specialized than other projects so it's lower cost compared to most scientific instrumentation which is nearly 100% bespoke for whatever instrument is being built.

Meanwhile, TMT is still facing tons of opposition: https://www.hawaiinewsnow.com/2019/09/26/solidarity-mauna-ke...

> Meanwhile, TMT is still facing tons of opposition

Which is one of the things that makes democracy and civil rights great: different people can express different perspectives and influence the decisions made.

People expressing different perspectives and influencing decisions isn't an absolute good. It certainly can be positive and desireable in many situations. In others it can be utterly destructive, such as the the anti-vax movement or climate change skeptics.

Your example is off the mark. What people mean by that sentiment is that as long as you don't harm others, you should have the freedom to do what you want. Climate-change and ant-vax are issues that impact everyone else on the planet.

No man is island. So even if you are just harming yourself by drinking or taking drugs you are also ruining your family and indirectly society by making that behavior more socially acceptable. So there shouldn't be absolute freedom in anything.

> you are also ruining your family

I effectively never had one, so does that make it acceptable?

> and indirectly society

I know plenty of drug takers that function fine in society[0]. I anticipate your response might be "they would function even better if they didn't", but perhaps forcibly removing choice from adults is also damaging.

[0] and some don't, to be sure.

For public safety, those that function well don't matter that much if the overall trend skews heavily negative though.

This is what it's like arguing with many anti-drugs person. Whatever you say, they'll counter it with anything to push their 'prohibitive' agenda.

It's not even that there's no room for compromise, there's no space even to discuss it, to try and understand their rationale. It's like being a kid again in a classroom with the teacher shouting at you that you can't do that and no they won't explain why.

The scary part is that drugs were only volunteered as an offhand example. Authoritarians (in this case openly) apply the same logic to literally any activity, such that even the most vague and indirect tertiary externalities can be twisted into an excuse to police other people. Even the most responsible engagement in [drug use]/[sex]/[motorcycle riding]/[controversial art]/[self-defense]/[political protest] is subject to their judgment and approval because your example might influence someone else!

But even though this loose standard can be stretched to justify literally any prohibition, in practice the only activities that get targeted in the name of community enhancement are the ones that make the group in power feel threatened or uncomfortable.

Maybe we need drinking licences. You need to pass multiple tests that cost a lot of money to administer, and if you are caught breaking the rules you get a fine or go to jail (depending on the legal framework, which rules you broke, and how good your lawyer is).

Okay, but you are conflating moral harm/duties with tangible physical harm. The first one is arguable, the second one (pollution of air, etc) isn't.

I don't think it is utterly destructive in the anti-vax movement. Dangerous and stupid, sure, but what if the government was trying to force you to put something else in your body that you thought was not in your best interests or that of your child? Isn't it an absolute good that you're able to speak up and resist?

> force you to put something else in your body that you thought was not in your best interests or that of your child?

It's not in the best interest of other children to let your children not be immunized.

One of the reasons immunizations work so well is because of herd immunity. The entire population doesn't need to be inoculated against every random mutation the virus will take. Enough of the population has good enough immunity that the virus can't take a foothold. But once you dip below a certain percentage, the virus gets free rein to spread and evolve again.

Effective immunization requires that we all mostly get immunized.

You don't have to convince me. I know all this and I'm not an anti-vaxxer.

> It's not in the best interest of other children to let your children not be immunized.

This doesn't change my point at all.

First, the idea that my child should be subjected to something harmful because it's better for other children doesn't fly with me. I doubt it flies with anyone. I vaccinated my kid for her benefit and for everyone else's, but if the choice is "everyone else" or "my kid"... I don't think you have to be a parent to see how that one shakes out.

Second, that's not how anti-vaxxers see it. They see it as bad for those children as well.

>the idea that my child should be subjected to something harmful because it's better for other children doesn't fly with me

They aren't being subjected to something harmful, they falsely believe that it's something harmful because they saw an infographic on facebook

>that's not how anti-vaxxers see it. They see it as bad for those children as well.

Yes, and this kind of toxic stupidity should not be tolerated as it puts everyone else at risk

If you want to boil this down to black-and-white you need to compare the past, present, and future deaths of the anti-vax movement against the solution of 'not tolerating' anything that doesn't meet your utilitarian ideal. And that's aside from the moral aspects.

It is black and white. Everyone who can needs to vaccinate otherwise we loose herd immunity. Full stop. Vaccines benefit far more people then they negativity affect.

You and authoritarian seem to be saying "anti-vaxxers are completely bad!" Well, congratulations. You're right. But no one here is arguing with you.

The issue is whether allowing people voice in influencing policy in a democracy is an absolute good if it means people like anti-vaxxers can still influence policy. I argued that from the point of view of an anti-vaxxer they are doing good, and that, you might find yourself in such a position one day. That's irrespective of whether the anti-vaxxers are right or wrong and if the hypothetical you is right or wrong.

And if it's not clear by now, (which it should be for anyone who read the thread): I'm not an anti-vaxxer; I'm not in favor of them; and nothing I've said here is in support of them.

You cannot say some people are negatively affected AND say it is black and white.

That is flat out wrong that vaccines aren't harmful. We have programs at the federal level in place that track and document the harmful effects of vaccines, including deaths caused by them.

If you wish to support your position better, you need to acknowledge the worries people have, not be deceptively dismissive of real worries.

Not an anti-vaxxer either, but it is absolutely not true that there is no potential harm from vaccination.

For one thing there's a risk of Guillain-Barre syndrome.

There's also an inherent risk with introducing anything at all into your body via needle -- where/how was it stored; what other quality controls were practiced?

Do you think there is more potential harm, both to an individual and to the people they come in contact with, from getting vaccinated or not getting vaccinated?

Of course getting vaccinated is the better option.

But that's not the question here. The question is whether someone should be forced to be vaccinated.

Not sure why this concept is so hard to get across.

It's not that respondents don't understand your position its because as a group we can't afford to accept it. The negative effects of abstaining from vaccination aren't felt merely by the families they are felt by everyone.

The 90% can't afford to let the 10% have their own way when it would hurt everyone. In other news you aren't allowed to do all sorts of things on your own property that threaten your neighbors safety.

> It's not that respondents don't understand your position ..

You're still not getting it. I don't have that position.

If children wish to go to a publicly-funded school and come into close contact with other children, then they should be vaccinated. Period.

If you want an exception for your child, then privately educate them.

The chilling effect you're seeing on your devil's advocate arguments are because anti-vaxxers have caused so much harm with their pseudoscience. There is no room for playing nice or entertaining a middle ground.

The government has stepped in and made public health choices for us already. For instance, we chlorinated and fluoridated the public water supply. If you want to drink bottled water, that's fine. This isn't even a powerful enough analogy though, because vaccination doesn't just impact individuals. Every act of rejection lowers the fitness of the population.

echelon, I agree with everything you write here.

Which tells me you're still not getting my point.

I don't understand the brouhaha around anti-vaxxers.

If some minority of children aren't vaccinated, how is that a threat to the rest who are? What's the point of the vaccinations if they aren't effective at protecting the vaccinated from the diseases carried by those who aren't?

I must be missing something, because it just looks like people meddling in the affairs of others. If a parent wants to have non-vaccinated children, I don't see how it's any different than a parent letting their children grow obese. It's their problem, live and let live.

You are missing herd-immunity.

A vaccine that only conveys, say, 20% protection to individuals can still convey ~100% protection to a group by tipping disease story from "spreads exponentially" (average_new_infects_per_person > 1.0) to "fizzles out" (average_new_infects_per_person < 1.0). That's called herd immunity. Even a modest minority of anti-vaxxers can sabotage herd immunity, leaving the rest of us with only the vaccine's individual protection margin.

Isn't herd-immunity concerned with those who aren't immune, so in this case, who aren't vaccinated?

Which just brings us back to worrying about the concerns of others.

What does herd immunity have to do with the lives of the vaccinated?

No because no vaccine protects everyone 100%. There are the young as of yet unvaccinated, the old, immunocompromised individuals and even those who are vaccinated can still actually get the virus just with far less likelihood.

An increasingly large population of infected risks giving the virus a foothold first in vulnerable populations, then in everyone especially as mutations in an increasingly large reservoir provide exponentially more chances to find more effective forms that bypass existing immunity.

A minority of stupid people can put everyone at risk. Ultimately diseases continue to wipe out species. There is no particular reason to suppose we are immune to calamity just because we have better tools to respond to it than dumb animals.

There is a very small portion of individuals who will have a bad reaction to vaccination and experience negative consequences up to and including death. These negatives are much much less than would be experienced by all people if the disease was allowed to thrive.

Its possible to imagine that given unlimited resources we could discover ahead of time whom might react so and avoid vaccinating them or further reduce such negatives but resources aren't unlimited so currently some die.

We are already killing some kids so that others may live and the majority already supports that as do I.

> There is a very small portion of individuals who will have a bad reaction to vaccination and experience negative consequences up to and including death. These negatives are much much less than would be experienced by all people if the disease was allowed to thrive.

This is very true, and there's no justifiable reason it should have been downvoted. The truth is more subtle than pro-vax or anti-vax dogma.

> Isn't it an absolute good that you're able to speak up and resist?

And yet we have lots of areas that are taboo: where speaking up or resisting will mark you as a danger, and you will be punished. #metoo

Another way to look at is that children have the right to not have their health jeopardised by the fact free opinions of their parents.

>Isn't it an absolute good that you're able to speak up and resist?

For the morons it's great, not so much for the millions of people exposed to diseases that had essentially been eradicated due to other people's stupidity

> People expressing different perspectives and influencing decisions isn't an absolute good.

I would say it is, as long as they're being honest (even if you judge their honest position to be wrong).

This was true for the ancien Grec, but in the 21 century manipulation at large scale are really efficient thanks to the technology. People honestly believe that vaccine cause autism and it doesn't change the problem it bring to the rests of us.

>People honestly believe that vaccine cause autism

These are also the scumbags that feed their autistic children bleach causing them to poop out their own stomach lining, and the parents think they are removing "autism worms"

Yes, the ability to protest is great. That doesn't mean that this particular protest is well grounded or positive.

TMT has fallen victim to an entirely unrelated political issue: the Hawaiian independence movement. There are people who believe that Hawaii is not legally/morally part of the United States, and they've chosen TMT as a highly visible project they can block, in order to assert sovereignty.

They make a number of claims to justify blocking TMT in particular. Their environmental claims are nonsense (nuclear-powered telescopes - imagine that!). They also claim that Mauna Kea is sacred to native Hawaiians, so that building a telescope there is desecration. That claim is actually extremely dubious, from a historical point of view. While going to the summit was taboo for most people in old Hawaii (as were many activities, such as men and women eating together), native Hawaiians also dug the largest rock quarry in all of Polynesia on Mauna Kea. There is also surprisingly little mention of Mauna Kea in extant chants from the old religion. But it's an oral tradition, so definitively proving that Mauna Kea wasn't as sacred as anti-TMT protesters claim is impossible. What's important is that the independence movement has made Mauna Kea's supposed sacredness a central part of their creed.

It's a sad situation, because TMT has the law on its side, and even with all the will in the world to accommodate opponents, TMT has no power to grant their central demand - independence from the US. The protesters fundamentally just want to block TMT entirely, as a statement about sovereignty over the mountain, and over Hawaii more broadly.

It is only great during a time when there is no instability between nations (which is not the case today). When you have nations that are vying to become a hegemonic world power , your own nation better be as damn efficient in building out its capabilities and protecting itself.

this is literally nimby

As I understand it, the opposition to the TMT isn't a NIMBY issue: it's more about a historically ignored group trying to gain influence over issues it cares about.

it's still nimby too

Not really. As typically used "NIMBY" has a component of hypocrisy. Just not wanting something to happen is "opposition". "Not in my backyard" connotes the idea that someone supports some project in principle, but not when it affects them directly. "I like wind power, but not when it blocks the view of my cottage", "I like high density housing, but not if it affects my property values", "I like mass transit, but don't want a subway station in my neighborhood."

In this case, "I don't want another giant telescope on my culture's sacred mountain" isn't about astronomy at all, it's about the culture (and the larger perspective of indigenous interest in local resources, and respect for a pre-existing treaty that wasn't quite honored -- these folks aren't primitives or hippies, they know very well this is a political process in the real world).

The majority of the indigenous interests support the telescope. This is about a minority of a group trying to gain status at the expense of everyone's interests.

They would equally oppose a luxury hotel or a housing development.

I don't think it's the same as NIMBYism either, because the people who oppose it aren't all in the area, and there are cultural issues and issues of colonialism involved.

That said, the idea that NIMBYs won't oppose a luxury hotel or housing development is laughable. My NextDoor is filled with people posting proposed development of our downtown, criticizing it with specious reasoning, and trying to rally people against it. The nature of the development doesn't matter. How much it will improve our property values doesn't matter. How much it will help with housing or traffic doesn't matter.

A luxury hotel... I can already hear them shrilly decrying how we don't "need to bring more people to the area," as stupid an argument as that would be for a hotel.

I was trying to conjure up an image of how most island economies are glad, at least initially, to see development that brings jobs.

I don't know how to flesh it out better.

Would they oppose a 5th luxury hotel being built next to 4 other luxury hotels?

> Would they oppose a 5th luxury hotel being built next to 4 other luxury hotels?

IIRC, the anti-TMT protestors would ideally like all the telescopes on Mauna Kea removed. However, obstructing the construction of the new one is the most practical present course of action for them.

I don't really see opposition to progress as great. But I mean that in general sense, there are some limits, and I know nothing about this specific case.

Unopposed progress is why we are now having concerns about the environment.

A wise comment befitting an account with that name.

I took your comment to mean, and I agree, that progress is subjective. For example if I oppose mining pits which utilize child labor, I would effectively be opposing the progress of technology which require the rare minerals that come out of them. Still progress though.

It's good that they can voice their opposition. It's bad to you that they're opposing progress according to your definition of progress. There is a distinction.

The other side of this is that there is an element of obstructionism built into the model of democracy. Too much process, back and forth, judge-intervention, lawsuits, counter-lawsuits, voting and representation, etc. It would be ideal if we simply allowed everyone to vote on it, and go with the majority outcome.

Affording ourselves insight into the cosmos I think is unreservedly progressive.

If Paris can move graveyards and cemeteries underground for progress, surely something similar can be arranged to enable progress on the one hand and afford people the ability to honor their ancestors and culture.

Oh, don't get me wrong. I fully agree that looking and moving towards the stars is progress we should be working towards and doing so delicately if necessary. There are too many fixable and silly-things happening in the world today that absolutely demolish our ability to progress as a society.

Why would anyone have a problem with a telescope? They produce almost no light and are also very quiet. I doubt the produce much traffic unless it's some museum as well.

Also putting a telescope near your home probably hinders addition of other things that produce light pollution or am I wrong?

because the telescope is supposed to be built close to the summit of the Mauna Kea volcano, which is a sacred site for the natives. It'd be analogous of putting the telescope into the middle of Jerusalem.

Historically, Mauna Kea is not the Jerusalem of the old Hawaiian religion. It's barely mentioned in the remaining oral tradition. There are other locations that were far more important, from a religious point of view (e.g., Kīlauea). It was taboo for normal people to go to the summit, but old Hawaii had a lot of taboos, and native Hawaiians also mined a huge amount of volcanic rock (which is great for making adzes) from the mountain.

The old Hawaiian religion we're talking about, by the way, fell increasingly out of practice from the early 1800s onwards, when the Hawaiian monarchy broke the taboos, defeated the priesthood in battle, and converted to Christianity. What we're actually discussing is a modern reinvention of the old religion, in much altered form. This modern version is heavily entwined with a political movement - Hawaiian independence.

But even if one accepts the modern practitioners' claims about what the old religion says, this isn't like building on the Temple Mount in Jerusalem. It's like building a mile away, beyond a ridge, in a location you can't see from the Temple Mount. TMT isn't at the summit, specifically because the project wanted to avoid any religious sites.

The old religions of the Americans have been practiced in stealth because they were punishable by death.

The fact that you go to Mexico and it seems like everyone is Catholic is because that’s what you had to make it look like if you wanted to not die.

It does not mean that the old religion disappeared. It means you won’t see it unless you are very deep inside the circle of trust.

The fact that you’re suddenly hearing about people practicing these things is not “new age” nonsense, it’s people finally having the visibility and support to do something publicly that it wasn’t safe to share until very recently.

It’s also people who may have never grown up with it, but whose great grandma practiced bits and pieces, who are re-learning from the handful of knowledge keepers how to begin again. That too is not “new ageism” it’s an endangered species growing its population again. It’s a delicate process that is just as important as any telescope.

And lastly, you may want to adjust your tone. You are talking about the murder and total cultural suppression of your opponents’ ancestors. This isn’t about the old CinePlex getting torn down, this is people’s basic tribal identity and their direct ancestors’ slaughter and slavery. These are not things you should just roll over with bravado.

I don't think you know what you're talking about, with all due respect.

The old Hawaiian religion was suppressed about 200 years ago, not by outsiders, but by the Hawaiian monarchy itself. Whether or not that was a good thing is a difficult question. The old social and religious system was extremely oppressive, with a dominant priestly class. The religion involved human sacrifice and strong strictures on behavior that people nowadays would find very troubling. The decision of the Hawaiian monarchy to break the power of the priests could be viewed as positive, as far as it allowed greater social freedoms to most Hawaiians.

You say that the new practitioners of the religion are essentially just coming out of hiding, and practicing the same religion they've privately held for a long time, but that's not entirely true. Some of the central claims they make about the religion (e.g., Mauna Kea as the most sacred place in the religion) just do not square with what's known about how it used to be practiced. Other elements, such as "kapu aloha," are clearly very recent inventions. It's very naive to just ignore the entire political context of the religious revival (the Hawaiian independence movement and the attempt to create a separate national identity) and the historical evidence about the religion, and accept all the claims made about the religion by the leaders of the anti-TMT movement, who just happen to be independence activists.

Jerusalem has had actually high levels of development, despite high density of folks living there. I think everything from trains to some crazy cable car ideas (I assume the later won't happen) are in the cards. Is this level of development allowed on Mauna Kea? It seems MUCH higher impact than a telescope. Look at some photos just for the residential density in Jerusalem.

It should go to the Canary Islands, where there is 100% support:


The Mauna Kea site is a better one, in terms of observing conditions. It's higher, drier, has fewer cloudy nights, better atmospheric turbulence conditions, etc.

Maybe we can knock down the Vatican and build this telescope, since we are in the business of ignoring the local's wishes.

It's also a place of immense cultural significance to the native population.

It appears that there was widespread support 18 months ago, even among Native Hawaiians: https://www.westhawaiitoday.com/2018/03/26/hawaii-news/poll-...

But the same article says that in 2016 support was much lower.

I wonder what is happening to change the level of support over time. Maybe the 2018 poll was just an anomaly.

The parent article (hawaiinewsnow.com) makes me sad, because it sounds like opposing the telescope is becoming a way of feeling cultural identity. The desire to feel a part of something is satisfied by mobilizing in opposition to something. I would like to believe that cultural expression and belonging can coexist with modern scientific inquiry. From this page it sounds like the project has done a lot of work to minimize the impact and do community outreach: http://www.maunakeaandtmt.org/facts-about-tmt/

Surprised to see no mention of tourists or cellphones. We learned about this telescope in astronomy class on Tuesday and our professor said the place was inundated with so many tourists that it was impossible to get any useful data due to the noise generated by all the cellphones. Part of the reason the telescope was built in such a remote area was to reduce the amount of radio noise from terrestrial sources.

That's surprising. I went there recently, and you aren't permitted to bring any electronic devices whatsoever - you have to leave them in a locker and then take a ~30 minute bus ride to the telescope.

They're also very strict about checking: you have to go through two different x-ray machines to check you didn't sneak any electronics through.

Perhaps the no-devices policy was introduced after the interference issues were encountered?

No, the no devices policy would have been there from the start, its as basic as forbidding open flames at a petrol station.

The need for X-ray machines due to tourists ignoring the ban is a more likely development.

Are those truly x-ray machines? Not just magnetic coils? Seems overkill and I'd object to being exposed to ionizing radiation just for the purpose of validating my claim that I don't carry any electronic communication devices.

It's actually a pretty standard setup in China anyway... Pretty much anytime you go onto an inter-city bus / train or into a crowded space (museum / exhibition centre) you will go through a metal detector and your bag through an x-ray machine. So it makes sense that they'd just use the standard setup that the local security company would be used to.

Most likely it's X-rays for your stuff and metal detectors to make sure you're not trying to smuggle anything past the X-ray machine.

No, it wasn't there from the start. The no electronics policy only started within the last two years. I know someone who has been there and has the pictures on her phone.

Maybe the tourists are present only a few hours in certain days. The article mentioned some discoveries so it must be working.

Those 'discoveries' are just confirmations of prior discovery by other telescopes of a particular repeating fast radio burst.

You can't discount it that easily: they report bursts unobserved by other instruments, which could be a second burst mechanism that hasn't been seen before due to its lower flux.

Also FAST has discovered about 100 new pulsars, in at least one case they detected a pulsar at a position Arecibo had observed three times already and not finding anything.

And that is as expected, the article mentions that this telescope is more sensitive but it has a smaller field of view so it is used to get better images of areas indicated by a different telescope that has a much larger field of view.

Did they build a football/soccer field next to it so that we can realize how gigantic it is by looking at the pictures?

More likely so the workers had some recreation while on assignment!

I just came here to comment on that :)

This is a smart move by China. There are a lot of reasons to do big science projects other than accomplishing the science itself. One of the biggest is that you get a lot of the smartest minds around the world in the same place as one another. The country that is hosting them will receive more benefits than the other countries participating (though everyone wins in some way). You also are more likely to get the spinoffs that always come off from working on difficult projects.

China is also building a super collider that's larger than CERN. The big question though is if they plan on doing an international effort (and if so, can they attract international scientists while operating an authoritarian state?) or if they plan on doing it only nationally (seems much harder to do and not as effective).

They have loose plans for building one, there is no current construction, or indeed even a definitive descision. Even when the chinese decide is uncertain: could be next year, could be in three years(1). The only thing that exists is a conceptual design, that isn’t even sited!

(1): https://indico.ihep.ac.cn/event/9832/session/0/contribution/...

FAST is actually having difficulty hiring (on-site specialists like operations director) the smartest minds because it's in a jungle in small-town China.

But yes, overall China is executing an excellent "brain drain" (not meant in a negative sense) by being willing to invest in these "keystone" projects when other countries are tightening budgets.

Telescopes generally have this problem though. Because it sucks to live out in the middle of nowhere and you typically want to bring your family (which means you need cities to support things like schools and recreation. Most labs/research sites I know are like this. China Lake is an exception. But even Groom Lake has has Vegas near it).

> There are a lot of reasons to do big science projects other than accomplishing the science itself

One is national prestige. I'm not sure that's a good reason (if that's what's happened here).

I think it definitely does help. National pride is definitely a factor that matters. You can say that your country is on the forefront of science. Personally I'm very happy to spend a lot of money on science. It helps push humanity forward and is good for the economy (ROI is high in the long run, though maybe not in the short term. Which is why government funding is better than commercial)

At the risk of misrepresenting chinese efforts, my point was a bigger scientific instrument might just be willy waving. Blowing resources doesn't necessarily get results.

If someone claims a new supercomputer place, the first thing to ask is whether they're getting real performance out of it.

(I'll repeat that this a question, and not an assertion that china's making a mistake)

Oh I think I misunderstood what you were saying.

> Blowing resources doesn't necessarily get results.

> If someone claims a new supercomputer place, the first thing to ask is whether they're getting real performance out of it.

So like TaihuLight[0] and Tianhe[1]? ([2])

I still think these machines add to national pride, but you're right that the money would be much better spent if it ALSO did actual science. I don't think these kinds of moves are as beneficial, because the benefits that I described in my first post are well known in the community (though not sure if they are well known by the public or even Rick Perry (though I know he's been told)).

[0] https://top500.org/system/178764

[1] https://top500.org/system/177999

[2] I work on super computers and from my understanding (I haven't personally used Taihu or Tianhe) is that these computers are "Linpack machines" (linpack is the metric used to quantify the rankings). That these computers are extremely difficult to work with (all super computers are difficult to work with, and so these are HPC guys telling me that they don't want to work with those machines and are much happier to work on machines like Summit, Sierra, or even Titan) and so not much science is actually done on them.

Whoa, you work in HPC? Wow.

I understood that the TaihuLight etc. were based on SW26010 cpus and as these use scratchpad rather than automatic cache hierarchies I assumed they were a bugger to program therefore were less efficient (it's not that simple but you know what I mean).

But I checked on https://en.wikipedia.org/wiki/TOP500#TOP_500 which gave, for this machine, Rpeak (theoretical peak) of 125 PFlops[0] and Rmax ("the highest score measured using the LINPACK benchmarks suite") as 93 PFlops. Which really wasn't at all bad compared to the US machines, so I wondered where that left my assumptions. But you now mention they're hard to use.

I'd assumed that if linpack was written and tested, you just used it and got the peformance. Apparently not?

(I don't work with supercomputers, just in case you hadn't noticed)

So a big part of what's hard in HPC (really depends on what you do in the area. I mainly just use the machines to run stuff. You don't write software on the machines) is getting things to install (and run as expected). The people that maintain the machines will generally have your basic stuff installed (things like GCC, clang, your intel compilers, python, hdf5, etc) and you can load different versions using modules. Anything not there you need to do a local build of (your software and anything that your software depends on that isn't a super common library). Building these packages can be a real pain because architecture is so different (some people work on things called Data Parallel Primitives that try to make these easier. One common software that uses this is VTKm. They us a lot of template metaprogramming, which results in crazy errors that are hard to read but many times works more easily). Basically take the frustration you have for building things from source and multiply that by at least 2.

So basically what I've heard about Taihu is that installing any packages and writing code for the system is even more of a pain (like adds months to your work (probably an exaggeration)) to write for. Libraries that are commonly used aren't supported and so many things need to be written by hand (including all the optimization). So they go (from my knowledge) fairly unused. Hence calling them Linpack machines (someone got linpack running and submitted test results. Doesn't say how utilized the machine is).

But this could also be people in the labs playing up lab pride too. So take everything with a grain of salt. I want to try to be fair here. (US labs do have lots of internationals at them, not just western countries, plenty of Chinese nationals. They just want smart people).

As for performance, it depends on a lot of things (it is actually REALLY hard to measure). Linpack is just a good baseline and has been highly optimized. But it doesn't tell you how fast your software is going to be because frankly your software could be completely unoptimized. It is highly dependent.

That said, having the fastest/biggest HPC computer doesn't mean too much. No one is running across the entire machine at one time. It is generally a lot of different programs and groups working on the same machine. There are benefits though. It is easier to have a single big machine than many smaller machines and it does enable you to do the science you want to do if you do end up needing a huge capacity. More bang for your buck. And for only a few hundred million dollars too, not a bad price.

Fascinating stuff, thanks!

What is the percentage of the sky it can observe? Should be fairly small.

This telescope moves the sensor head across the surface, changing the actual angle of the observation. The big poles around it are what suspends the head over the surface. It has actually a huge angle of observation. According to WP, 60° in its small 200 m aperture and 26.4° in its 300m aperture.

FAST can also move it's "mirror," the shell has some huge number of triangular sections on wires, so it should be able to point even more than arecibo which has an immutable reflector. Both have adjustable focal points (sensor head) on wires like you describe.

Keep in mind that this is the the range of motion of the primary beam, not how large a patch of the sky is visible to the receivers.

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