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So sharp and quick witted at that age.
What a great interview
So interesting to hear the street-level policy effects of the Carter administration talked about like this. It adds something intangible to this video.
It's too bad that talk shows aren't like this anymore. The Letterman producers from the 1980s deserve kudos for finding interesting guests (not only Grace Hopper, but also Isaac Asimov, Doc Edgerton, Don Herbert, and plenty of others).

Aside from Neil deGrasse Tyson or Dr. Fauci, it's pretty rare to see a scientist on a late night show now. For all the empty talk about the importance of STEM, it's pretty unlikely that you'll see a pioneer of computer science.

The flip side is that this was the _only_ place you ever saw them. It's not difficult to find endless videos of Neil deGrasse Tyson or Dr. Fauci on YouTube today. In the 1980's, you didn't see people like Grace Hopper or Asimov _at all_ except for this sort of appearance on a talk show or maybe something brief on PBS if you were lucky to catch it at the time it was broadcast.
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That's true, and there were only the three commercial networks and PBS (as of the 1970s) on which to catch appearances.

Radio was somewhat more open, and Asimov writes of hearing (and not recognising) his own voice coming from the radio in his autobiography (his wife clued him in).

That said, I just searched Invidious for any appearances of Kim Stanley Robinson, one of the most notable current science fiction authors, on any of the late-night shows (Colbert, Kimmel, Fallon) ... and there's nothing. Though tons of other videos featuring KSR:

https://yewtu.be/search?q=%22kim+stanley+robinson%22+%28kimm...

The fastest reactions in our body (hydride shifts, very small rearrangement of atoms to maximize charge stability) take a mere picosecond. This nanosecond is 1000 times longer than a picosecond. Try to imagine that the molecules in your body are spinning at crazy frequencies and rearranging themselves incessantly at that speed.
I had a genuine Grace Hopper nanosecond from when she visited my high school. Sadly lost now.
I loved this!

It ties so well the another comment about the speed of computers on the front page:

> On a 3GHz CPU, one clock cycle is enough time for light to travel only 10cm. If you hold up a sign with, say, a multiplication, a CPU will produce the result before light reaches a person a few metres away.

<https://news.ycombinator.com/item?id=31769936>

The foot has been criticized for being an arbitrary measurement with no real relation to a repeatable physical distance.

However, it turns out that a foot is within 2% of the distance light travels in a nanosecond!

Because of this, the foot becomes really convenient when talking about latencies. For example, if something is 6 inches away from the cpu on a motherboard, the lowest possible latency to reach that is 0.5 nanoseconds.

Time to push for the adoption of feet everywhere /s

Reminds me of the whole "Fahrenheit is awesome because 0°F is too cold and 100°F is too hot"

(BTW, for me 0°C is too cold and 40°C is too hot)

Celcius is nice because -30 is the limits of cold that I want, and +30 is the limits of hot
> For example, if something is 6 inches away from the cpu on a motherboard, the lowest possible latency to reach that is 0.5 nanoseconds.

Isn't that going to be insignificant compared to everything inside the computer on both ends?

Not if you're making computers.
To expand on this: if you're designing / building / assembling a computer or cluster, and components are 6" apart, then the minimum latency for communicating between those components is 1 nanosecond.

Given clock speeds of multiple GHz, that means spending an entire clock cycle or more simply communicating between components.

See also the case of the 500 mile email: https://www.ibiblio.org/harris/500milemail.html

(A Sendmail misconfiguration resulted in a maximum response time of 3 milliseconds, or roughly 500 miles of travel at the speed of light. The observed behaviour was that a uni campus computer could send email only within a 500 mile radius, as noted by the statistics department.)

> Given clock speeds of multiple GHz, that means spending an entire clock cycle or more simply communicating between components.

Yeah that's expected isn't it? That's why we have caches on die. Nobody is out there expecting main memory reads to retire in a clock cycle, let alone IO! I don't think even lower tier cache access retires in a single clock cycles. That's just not how processors work these days.

It's not just single systems.

It's clusters. It's datacentres. It's tools which span the globe. Or extend into space.

The Web by default is now transacted over HTTPS. This means that every session requires a TLS handshake:

- Client hello

- Server hello + key

- Client key exchange.

- Server finished.

- Client finished.

- Data transfer begins.

That's six exchanges, and three round trips. For an antipodal set of hosts, at 300ms per trip, that's nearly 2 seconds just to set up a session. If you're communicating with a Moon base, it's eight seconds.

And if you're using a tool or protocol which presumes cheap or fast round-trips, and uses a lot of round trips, you may find it's unusable.

Some years back a multi-campus site rolled out a remote-console tool that worked across platforms in datacentres --- we had both Linux and Windows hosts.

Working locally with the DC one building over in the campus, or even with a facility elsewhere in the province, performance was laggier than local, but tolerable. The team operating out of Dubai was waiting five minutes to see login screens presented.

Distance is time.

TLS1.3 removes one roundtrip. HTTP3 (QUIK) remove more by combining the TCP handshake with the TLS handshake.
SPAs return those roundtrips with a vengence.
Which gets back to my, and Hopper's, initial point:

Space adds time.

If you're doing something, anything, which involves communicating between two or more components frequently, then the further apart those components are, the longer it will take.

(It's also more likely to be affected by other issues --- latency, unreliability, interference, injection, exfiltration, ...)

And that will grow linearly with distance as a multiple of interactions.

There's a lot of code and processing which presumes delays are small and components are near. As those assumptions are violated, performance tends to degrade spectacularly.

Love your comment, this quick rule is critical, but... Don't forget that the relative permittivity if PCB material is roughly 4, so the rule for circuit boards is 6" per nanosecond :)
A similar heuristic is very useful for acoustics: the speed of sound is close enough to 1 foot/ms to be a great rule of thumb for estimation.
Or... rule of foot, for the compulsive unit-cancelers out there
Welcome to the UK in 2022!

You'll even get a crown logo emblazened on the nanosecond ;)

I thought if the US ever switched from Imperial we should just switch to light-nanoseconds since its so close and then make fun of the metric folks for being Earth-centric.

Units of weight / volume would be a pain though since a cubic light-second of water is about 7.118 US gallons and weighs (@1g) about 59.227 lbs at the melting point of ice.

Of course, we should still go with base 8 like the Yuki tribe (spaces between fingers instead of fingers because that's how many bottles you can carry).

Light nanosecond depends on 'second', which is litteraly earth centric :-)
Less Earth centric than the distance from the North Pole to the Equator. We'll still use seconds on Mars.
And you can use feet on Mars, despite there being no actual feet there.

The second is 1/86,400 of a nominal Earth sidreal day. More or less.

Slightly less with time as the Earth's rotation is in fact slowing.

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That was charming. Great demonstration of scientific communication. Great visualization.
Sometimes I forget how militarized the computer industry used to be, probably still is, in one way or another. For every Stallman and Aaron Swartz there’s a Grace Hopper dressed in military attire while talking about computers.

Sad, too, that I haven’t seen any news in here today about Assange’s extradition to the US, at least not on the front page.

I saluted her once. No idea who she was, she was an old lady standing at a bus stop on base, wearing an odd (dated) uniform with an unusual rack of ribbons.
Is there a long version of this story?
I'd heard that in the army, once you reach General, you get to pick out your own uniform (she made it to some level of admiral during her service)
I love this so much. Computing is right up against the limits of the universe and seeing that your 4 ghz processor has a cycle time of about 7 light-cm shows you exactly how close we are to that limit. Looking at the computing time spent on accessing a remote server 8000 km away also keeps things in perspective.
Can we take a moment to acknowledge her incredible presentational ability? She was charming, wry, slightly subversive, and still conveyed a really cool scientific concept in one brief talk.
I've noticed that the prep-school-to-Ivy pipeline is great at producing people with that quality.

I just checked and, sure enough, that's exactly what she did.

[EDIT] The quality of being a confident, engaging conversationalist and presenter, I mean.

For her it was The Hartridge School and then Yale. Hartridge, in its modern form as the Wardlaw-Hartridge School, runs a bit over $40k/yr by the time you're nearing the end, down to about $16k for pre-k, though many won't be paying full sticker price.

Charming, wry, and slightly subversive is all her personality. However, more than a few people who have been on the receiving end would argue with you about "charming" and "slightly".

Presentation ability, however, was learned and practiced a lot.

She used to make all her subordinates give oral reports weekly on written articles she would pass out and then discuss as a group.

If you committed any of various presentation sins, you had to dump a quarter into the penalty jar.

Her subordinates got very good at presentations.

This is the first time that I've ever heard her speak. I have to say, she's amazingly charming and charismatic.
"...we should hang one over [programmers' desks], or around their necks so they know what they're throwing away when they throw away a microsecond." Relevant forty years later.
That line really stuck with me
My grandfather got his PhD because he lost an argument to Grace Hopper because she had a PhD and he didn't. He was working for the Navy at the time, and he wanted to use a higher level language for some operating system they were building. Grace Hopper thought that higher level languages were only suitable for business applications, not other computing purposes where performance was more important.

This is a link to a paper he wrote about one of the first cross compilers that they had built: https://dl.acm.org/doi/abs/10.1145/367436.367477