Hacker News new | past | comments | ask | show | jobs | submit login
Neil deGrasse Tyson AMA (reddit.com)
242 points by pbj on Nov 13, 2011 | hide | past | web | favorite | 62 comments

So, so many excellent quotes in that discussion. My favorite:

"Kids are never the problem. They are born scientists. The problem is always the adults. The beat the curiosity out of the kids. They out-number kids. They vote. They wield resources. That's why my public focus is primarily adults."

Preach it, dude.

Interestingly, South Park has been conveying this message message for over 10 years, and I think the generation that grew up watching South Park innately understands this already and at a younger age.

Really interesting. A couple of physics things I did not know that Neil mentions:

1) The fact that an electron has no known size -- it's smaller than the smallest measurement we have ever made of anything.

2) That Quarks come only in pairs: If you try to separate two of them, the energy you sink into the system to accomplish this feat is exactly the energy to spontaneously create two more quarks - one to partner with each of those you pulled apart.

Huh, I thought Quarks only existed as triplets.

They only come in "colorless" sets. The "colors" (which are just suggestive names and have nothing to do with light colors) are Red, Green, and Blue, along with anti-Red, anti-Green, and anti-Blue. Therefore, there are basically two options: mesons, which contain a quark/anti-quark pair (e.g. one Green and one anti-Green) and baryons, which contain quark of each colors (RGB, or antiRGB). Tetraquarks, pentaquarks, and hexaquarks have been searched for in experiment and would not violate the colorless rule, but have never been found. Physicists would prefer to be able to calculate from first principles whether such states are possible, but it turns out that no one knows how to do the calculation because of the non-perturbative nature of the strong force.

[Many caveats. For instance, any given hadron (the collective name for things made of quarks, which to date means only mesons and baryons) is not actually made up of quarks with definite color, but rather a quantum superposition of many possibilities. I think mesons, for example, are always a balanced superposition of R-antiR, G-antiG, and B-antiB. So you could never point to a given meson in an experiment and say "that meson was blue-antiblue".]

See also:

Q: Since time slows relative to the speed of light, does this mean that photons are essentially not moving through time at all?

A: yes. Precisely. Which means ----- are you seated? Photons have no ticking time at all, which means, as far as they are concerned, they are absorbed the instant they are emitted, even if the distance traveled is across the universe itself.

And we, as humans, are emitting photons right now. Little pieces of us are right now instantly traveling across the universe and colliding with other stars, planets, etc., or flying through the void - instantly - to who knows where?

This answer bothered me. Is he just saying that any supposed delays of "light" we can set up through experiment are really just delays in instantaneous absorption/emission pairs, or is he talking about entangled photons, or some preferred space of simultaneity, or photons not being particles but vectors in a timeless configuration space?

I loved this reply. Clarifying and correct, as far as I can tell.


Most probably he is talking about the fact that proper time for all events in Photon's own frame is zero, i.e. a frame that move with speed of light will notice that all events are instantaneous.

> Photons have no ticking time at all, which means, as far as they are concerned, they are absorbed the instant they are emitted, even if the distance traveled is across the universe itself

Yes. Or another way of looking at it, from a photon's perspective the Universe has no size at all! I love that.

Obligatory xkcd:Prairie http://xkcd.com/967/

re electron: It's probably more accurate to say "size" has no meaning at that scale. Particles turn into waves, spacetime isn't smooth, etc.

>It's probably more accurate to say "size" has no meaning at that scale

Not at all. Size has unambiguous meaning down to the Planck scale (10^-35 meters) and electrons simply haven't been probed at scales smaller than 10^-22 meters. They could very well have heretofore-undetected structure (e.g. preon models) on the scales of 10^-20 while still have fifteen orders of magnitude (about the relative span between an atom and the radius of the earth) over which distances are perfectly sensible.

Likewise, before the deep inelastic scattering experiments of the 60's, physicist had no direct evidence that neutrons and protons had any internal structure. All they could say is "we know that if they have internal structure, it's smaller than this length scale".

[FYI: The Planck scale is (arguably!) where the notion of size becomes murky because quantum fluctuations in the background spacetime (against which the sizes of things are measured) become substantial. Of course, no one has ever seen (even indirect) evidence of a quantum fluctuation in spacetime. And, as is well known, appling quantum mechanics to gravity and spacetime is full of difficulties. But most physicists believe there are such quantum effects because it seems damn near impossible to reconcile a classical spacetime with quantum everything else.]

Size of what, then? Its not a particle. Having internal structure doesn't mean volume makes sense. You're right that distances do make sense, and he probably meant the electron has no known internal structure. But I don't know how you'd talk about size unless you mean a zone of probability of where it is.

It is a particle. With a wavefunction. HN isn't the best place to teach quantum mechanics, but suffice it to say that the notion of spatial wavefunction spread is completely separate from the idea of particle being point-like vs. having internal structure of significant volume.

It is a particle, just because it has a wavelength doesn't mean it's not a particle.

An elephant has a wavelength it's just that it's rather small compared to the elephant

Indeed. See De Broglie's equations.


My personal favorite:

Q: If you could add one course to a student's curriculum, what would it be?"

A: Course title every university should offer: "How to tell when someone else is full of shit"

He is one of my heroes. So charming, funny and educating at the same time. His speech on the islam downfall in the 13th century due to some "prophet" claiming that math and devil were interconnected was much enlightening on how religion actually stops scientific progress.

I was in the middle of one of his talks and heard this exactly. I agree...but allow me to just correct one thing.

The "prophet" was a sheikh/imam in Iraq (?) that said math and Satan were connected. Islam had - up until that time - managed to have some pretty amazing feats.

That said, it's interesting how we blindly take advice from men with authority. Whether that's religious figures, famous people, or politicians.

Thanks for the correction kloncks!

Not trying to excuse myself, but I'm simply not good at remembering details. Would have to watch the video again!

No worries!

It's my view that religion often isn't the thing that impairs scientific learning. Rather it's men's interpretation of those events.

Just needed to make that subtle correction :)

Ideology is a superset of religion, and like fire, it can be used for either creation or destruction.


"Ghazali has sometimes been referred to by historians as the single most influential Muslim after the Islamic prophet Muhammad.[6] Others have cited his movement from science to faith as a detriment to Islamic scientific progress.[7]"

Does that one instance preclude all of the other people that contributed to science, who also had faith?

deGrasse's observation was that when a scientist reaches a point where he can't explain, or understand something often he attributes it to God... And then years later someone else find it's explanation, until he stumbles onto the next problem.

It's all good. I gues it's okay to put God where your knowledge limits you, or the current more wide one, but just don't spread it that it's because of God.

e.g. God is "what we don't understand"

Here's his lecture on this, "The Perimeter of Ignorance": http://www.youtube.com/watch?v=S1HXuiIBF3I

Thanks again! I somehow remember different setting, or just different link, or video cam, but it's the same lecture that I watched months ago.

It would help if their faith is what drove them to pursue scientific endeavors. And that is sometimes the case, in fact. But for every "understand the mind of god" faith-driven scientist there are at least one thousand screaming, irrational, dangerously unbalanced regressives who are one papal bull or fatwa or Dianetics away from ushering us into a brutal and stupid dark age. Like many human inventions religion can be a great thing, but it often isn't.

It would seem then the indoctrination of individuals is the issue here, not religion in itself. The current process of propagating religion through the oral teachings of priests and the dead letter of holy texts has given rise to fanaticism, pitting groups against one another.

Not disagreeing/agreeing, but do you have any evidence to back up the claim "for every "understand the mind of god" faith-driven scientist there are at least one thousand screaming, irrational, dangerously unbalanced regressives"?

No, sorry. This isn't Wikipedia.

Exactly. Just because I declare something doesn't mean I have to back it up with facts. I trust my gut. That's where the truth lies.

Not every turn of phrase entitles you to a link, you literal-minded buffoon.

Great! Hostility. A welcome addition to a discourse. What you said wasn't a turn of phrase. You stated it as a fact.

Q:What is your favorite fact about the Universe?

A:That is will never end. That it's on a one way trip of expansion. Something that many find to be philosophically unsettling. My view is that if your philosophy is not unsettled daily then you are blind to all the universe has to offer.


That's nice and all, but most humans in the world (including the western world) don't have the luxury of being able to let themselves be unsettled daily :/

Most of them could have this luxury. They pick other luxuries first.

Which is, in my view, a mistake. Those who seek out challenge tend to end up with a lot more luxury than those who don't.

This is probably a privileged viewpoint which is only possible in certain cases, i'm guessing (i'm not saying that you or me are privileged, necessarily...just that it's still a 'luxury' to some extent)

So he's skeptical of the singularity but he thinks we'll be able to live forever in a lifetime or so. Weird.

They're two very different ideas, even if they're often shared by the same people.

The singularity is all about AI surpassing human intelligence. On this front, I can tell you after having studied a lot of AI for the past three years, we are not close. We're a lot further than many people think, but still not quite that far.

As for extending lifespans, this is something we've been doing from the dawn of medicine. We've been making significant strides here for thousands of years, and as Aubrey DeGray puts it, we've become very efficient mechanics on the car that is the human body, and we're only getting better at it. There's a lot of research being done on slowing the aging process and beating genetic disorders, which are two of the largest barriers to extremely long lifespans for humans.

I agree with your premise. I too am skeptical of a singularity although I am hopeful of at least a Feline level of intelligence within the next decade. But the way these things go, the space of ideas is probably non-euclidean and certainly very high dimensional. It is possible that in the dimensions we are used to looking at things a singularity seems far away but is actually right smack in front of us in another dimension. So I remain agnostic.

Note also that - at least as far as I am aware - we have not managed to extend lifespans. Erastothenes for example lived till 82, at or more than the current expected lifespan of many western and first world countries. We have only increase the probability of arriving near the maximum life span by dealing with famine, war, diseases and optimizing diets and nutrients and lifestyle.

Well, we've increased average lifespans significantly, which matters to a great many people more than if .001% lived to age 200.

That said, is there any way to know if we've increased the maximum lifespan? It seems that accurate birth-date records in many parts of the world didn't start until the 1900s, as there's even difficulty 'verifying' the oldest person in the world today.

You're probably right that on the top end we haven't seen a ton of progress though, I think that first we have beat the things that tend to kill you in old age (cancers!) before we'll start dumping major resources into actually preventing the damage from aging itself that causes us to top out a little after 100.

Hopefully we'll also manage to reap an affordable vaccine or cure for malaria and some of the nasty diseases of tropical poverty in the next 20 years too, which will help that average skyrocket even more.

Has anyone considered the idea that perhaps this "AI" has already arrived in the form of the collective intelligence of the Internet? That perhaps the "Singularity" is simply a shift of scope in terms of consciousness from the individual to the group? Much like multicellular organisms evolving from single-celled creatures?

I just think this makes a lot more sense than the whole "we will build a conscious robot" thing, especially since many of the innovations that are used as evidence of an approaching singularity have helped human beings become ever more tightly interconnected.

This isn't quite the feedback loop that the AI singularity folks talk about, but the Internet is one heck of a positive feedback loop, much much tighter than technological progress feedback loop before it. Makes me excited for where we'll be 5, 10, 20 years from now as the rate of acceleration speeds up.

I don't think this started with the internet; the internet just made collective consciousness vastly more efficient. Just as information is processed algorithmically within the brain, information also passes from person to person via language, print, technological invention, etc.

We all want to believe that our consciousness is fully independent, but it's pretty hard to separate from our memetic history. Perhaps someday we'll be able to wire our brains together physically via wetware, and our philosophical questions about individually will take on a whole new level of complexity.

> The singularity is all about AI surpassing human intelligence.

This is a common misunderstanding. According to Kurzweil's timeline, AI surpassing human intelligence is only a stepping stone to the singularity, the former happening around 2029, the latter around 2045.

Rather, the singularity refers to the point at which the exponential slope representing technological progress begins to approach infinity. What this mathematical model means for reality is anybody's guess, and the majority of the predictions that have been made are pure conjecture.

It's not a misunderstanding, it's a different theory that also falls under the umbrella of "singularity". http://yudkowsky.net/singularity/schools

To me, the name actually seems like a better fit for Vinge's or Good/Yudkowsky's predictions than Kurzweil's. They both have specific "singularity" points, while Kurzweil's "singularity" is just an ever-growing exponential (or super-exponential).

He also suspects we're a decade or less from discovery of life on another body in our solar system.

I'm not skeptical of the singularity but I can see how/why an intelligent person could be. (Though I do feel it's worth considering that semi-sentient software could precipitate singularity-like changes without being able to pass the Turing test. I mean, it's sort of inherently myopic that we base the distinction of when a machine has crossed the threshold of sentience based on whether or not it's as smart as/smarter than a human. That could turn out to be a completely useless metric.)

My understanding of the arguments in support of meaningful extension of human lifespan (trending towards immortality) in the foreseeable future is that we're ±100 years from a development that results in (let's say) a 20 year bump, before those 20 years are up we will have accomplished a 60 year increase, within the following 60 we'll have managed to tack on 180, etc.

I do think mind uploading is probably a much more sustainable approach to Immortality for Everyone!®—then again, that's a lot of electricity.

"we're ±100 years from a development that results in (let's say) a 20 year bump, before those 20 years are up we will have accomplished a 60 year increase, within the following 60 we'll have managed to tack on 180, etc."

Predicting the future by extrapolating a trend without bound, that's kinda like the singularity. I have trouble with this sort of thinking. It's a little too pat, a little too wishful, requires a little too much reliance on faith. Things are never that simple. You can't just find one screw and keep cranking on it indefinitely. Progress relies on the occasional blacksmith[1].

And this is good. It helps social mobility. I have a hard time imagining a metric that wouldn't entrench a tiny set of haves if it grew without bound. Monotonic progress perpetuates the status quo, like trees stunting the ground around themselves. To avoid it requires periodic creative destruction. Ends of eras. The saturating of metrics.

(If I could still edit my original comment I'd replace 'weird' with 'interesting/weird'.)

[1] http://en.wikipedia.org/wiki/Johannes_Gutenberg

you don't need to live till they discover immortality, you need to live till the rejuvenative rate of extension of existing lifetimes crosses one year per year. (i think i stole that from nancy kress)

Why is that so weird?

Anyone interested in NdGT, check out the show he hosts: Nova Science Now


You can watch full episodes online, no commercial interruptions after they start. It does a good job at filling the popular science video niche, in addition to Through the Wormhole with Morgan Freeman.

I have been looking for a good science show, but Nova scienceNOW wasn't it. Not so much the content as the absolutely juvenline format.

Can someone explain how I have misunderstood and the show really is meant for kids? Because it's designed like a kid's show, complete with silly music, wacky editing, colourful demonstrations/analogies to illustrate scientific principles, and narration that sounds as if written for a toddler. In this respect it's almost as unwatchable as Michio Kaku's (who's ordinarily a bright guy) weirdly infantile Science of the Impossible series. (It's also an incredibly American show, formatwise, extremely brash and loud and fluffy.) I started watching the show as I'm a fan of Tyson, but I ended up disappointed.

For now, the only regular series (as opposed to one-offs like Jim Al-Khalili's excellent shows on atoms and chemistry, or Sagan's Cosmos) I consider worth watching is BBC's Bang Goes the Theory (http://www.bbc.co.uk/programmes/b00lwxj1), which is fairly obviously targeted at teens, but has some good content. Two of the hosts are fairly annoying generic twentysomethings who do the show as though it's some kind of music video programme, but the third guy is an adorable geek with an obvious passion for science and engineering, and they have some assisting hosts who are quite quirky.

I can't agree with you more, on one hand the technical detail is somewhat increasing in American shows, but the over production and gimmicky nature certainly overshadows it. I'm always impressed by the technical level of BBC shows in comparison, but the best content is online, usually in lectures, and not TED.

They probably think they need the flashy production style to attract mainstream viewers, and in the US, perhaps that's true.

But I was similarly annoyed with Brian Cox's Wonders of the Solar System, which is beautifully designed and calmly edited, but comes across as really fluffy thanks to the lack of scientific detail and the gushing, ultrapositive personality of Cox, who describes everything as "brilliant" and "mindboggling". I like Cox, but he's a bit over the top.

I've found myself hunting down online content such as TED, and also Nottingham University's work, such as the periodic table of elements series (http://www.youtube.com/user/periodicvideos).

> Popular science, sometimes called literature of science, is interpretation of science intended for a general audience. http://en.wikipedia.org/wiki/Popular_science

Conflation of genres imo, both science shows and "popular science" shows can be enjoyed independently of one another, similar to how adults may enjoy both drama and comedy. From what I've seen of Bang Goes the Theory on youtube, it appears to be a clone of MythBusters and cover much fluffier one-off engineering problems simple enough to reproduce on TV.

On the other hand, ScienceNow is more of a newsmagazine that highlights what several different researchers are currently working on, and why they are interested in that problem. Ex: natural language processing robots, growing human ears on mice for reconstructive surgery, etc.

It's true that "Bang Goes the Theory" has elements of Mythbusters, but it's focused on the science as opposed to the action movie stuff. The programme is basically "popular science -- you know, for teens!". Their magazine style format typically has one segment where they put a scientific hypothesis, law or principle in practice by building various gadgets. Other segments are news-related stuff, such as (just after the Japanese earthquake) a long segment on the science of tsunamis. I'm not in the target demographic at all, so I don't really follow it, but I appreciate their focus on educating kids and encouraging scientific thinking about young people.

Glad to hear my programmes are well received. If you haven't seen it, you should also check out "Secret Life of Chaos" - on YouTube.

Jim Al-Khalili (Twitter: @jimalkhalili)

That was unexpected! Hi! Will check out the Chaos programme. I actually watched your doc on the aftermath of Fukushima earlier this week, and was very pleased with how balanced and low-key it was done; it was also unexpectedly moving.

"The Story of Electricity" and "Everything and Nothing" is also in my queue. And your University of Surrey session! You're a prolific guy! Between all the documentaries and books and radio programmes and lectures, do you find any time to do science research at all?

"pedagogical enthusiasm" - my new favorite term.

Registration is open for Startup School 2019. Classes start July 22nd.

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact