In the spirit of the Lindau Meeting, we present a dialogue between a Nobel laureate and a young researcher. This interchange started online, where it continues to unfold. Here is a digest of this conversation, which has developed across time and space

Mao, Minnie Yuan

Mather, John C.

NASA Technical Reports Server

'tiij''':UI!.'' 
A conversation 
about observation 
In the spirit of the Lindau Meeting, we present a 
dialogue between a Nobel laureate and a young researcher. 
This interchange started online, where it continues to 
unfold. Here is a digest of this conversation, which has 
developed across time and space. 
"I'm trying to figure out 
what my role is in the 
world of astronomy. " 
Dear Professor Mather, 
[t was really lovely to meet you at the 
Lindau Meeting. [had a wonderful , thought-
provoking week that left me feeling buzzed 
up and raring to do science! 
My name is Minnie and I've just started a 
postdoc at the NRAO. I submitted my PhD 
on the cosmic evolution of radio sources in 
April and will (hopefully!) graduate from 
the University of Tasmania in December 
this year. New Mexico is somewhat different 
from Tasmania, but I'm really enjoying it 
here - especially being based at the array 
operations centre for the Karl G. jans1:)' Very 
Large Array (VLA). 
This brings me to why I do astronomy: I 
love observi ng. [ love the process of deciding 
to 'look' at something, setting up the 
telescope, waiting in breathless anticipation 
for the photons to hit the detector, or 
watching the cross-correlations dance across 
a computer screen. I even love reducing the 
data, knowing that shortly I will be seeing 
something no one has ever seen and using it 
to answer my science questions. 
What do you think will be the most 
importan t result to come fro m the JWST? 
Will they be driven by predicted theories 
or by observations that yield completely 
unexpected results, which we couldn't 
possibly have known had we not observed 
something new, as was the case with the 
Hubble Deep Field? 
I love my new job. Learning aU about 
the VLA isso much fun, but now that I'm 
starting to get used to the fact that I'm no 
longer a student, I'm trying to figure out 
what my role is in the world of astronomy. 
Clear skies, 
Minnie Yuan Mao 
''After aU these years, 
we still have a hard time 
making a theoretical 
supernova explode." 
Dear Mirutie, 
Thanks for your letter! I Like to be caUed 
John; I'm still not used to formal titles. 
My owl1 passion for physics and 
astronomy has a lot to do with a desire to 
build tllings. When I was a teenager [learned 
a lot from the Scientific American monthly 
feature called The Amateur Scientist, and I 
borrowed tlle 3-volLune book series Amateur 
Telescope Making from the library over and 
over again. I did build a small telescope, but 
II O C TO B E R 20 12 VOL 490 NA T U RE 55 
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"liliN']1 PHYSICS MASTERCLASS I 
I didn't have the patience to grind a mirror 
- I bought that. I also loved thinking about 
electronics, and I wanted to be a ham radio 
operator, so I assembled a Heathkit AR-3 
radio receiver (with vacuum tubes) and read 
The ARRL Handbook from cover to cover, 
over and over. 
There's a wonderful book by Martin 
Harwit called Cosmic Discovery that lists 
the greatest d iscoveries in astronomy, and 
shows what made them possible. In almost 
every case, the discovery came from new 
equipment, and in a pretty large fraction 
of cases the equipment was designed for 
some other purpose. So I see a path to 
great discovery: imagine a measurement 
that could answer a question, and build 
something to make the measurement. Then, 
either you answer the question, or you find 
something new. But in either case, it will 
be something nobody else could do. Have 
you given any thought to good strategies fo r 
making your own discoveries? 
That leads to your other question: what 
will be the most important d iscoveries 
with the JWST? Of course, I don't know 
specifically, but it seems that surprise is 
part of importance - if everyone knows 
something already, it is not a discovery. No 
theorists or obser vers predicted the correct 
story for galaxy formation before the Hubble 
Space Telescope was launched, neither group 
predicted cosmic dark energy or dark matter 
(though Fritz Zwicky saw evidence for dark 
matter in the 1930s), and neither predicted 
the nature and abundance of planetary 
systems beyond our own Solar System. My 
friends doing numerical simulations of stars 
and galaxies in supercomputers agree that 
they are not going to predict what we will 
find wi th any certain ty - the complexity is 
just too great. And after all these years, we 
still have a h ard time making a theoretical 
supernova explode. 
NASA's John Mather says discoveries come 
f rom new equij>ment. 
So, I think the JWST will lead to some 
great surprise that nobody is even thinkin g 
about today. Perhaps, you will be the one to 
fi nd that sur prise. 
With best wishes for your new role as a 
Discoverer! 
John Mather 
"Learning is not just about 
accumulating information; 
it's also about the process of 
getting that information. " 
Dear John, 
I like the 'discoverer' tag: I think that 
is what science is about - the discovery 
of new things, new phenomena, new 
concepts, new ideas. 
Minnie Mao beli eves in j>ushing a 
telescoj>e's capabilities. 
You asked if 10 given any thought to good 
strategies for making my own discoveries. 
I've thought about this a lot. When I was 
applying for postdocs at the end oflast 
year I looked for jobs that had a telescope 
support element. I wanted a job that would 
let me get to know the telescope. I figure 
that understanding a telescope's capabilities 
and limitations will enable me to ask science 
questions that the telescope is able to answer. 
I did my PhD in Aus tralia where I spent 
a lot of time at the Australia Telescope 
Com pact Array (ATCA). I learned so much 
by being on -site, th ings like how m uch 
microwave ovens affect observations at 
13 cm (a lo t!). Experiences like these enabled 
me to understand my data intimately and 
hence distinguish real science from image 
artefacts and other distractions. As sud l , 
I felt like I was able to tailor my projects to 
make the most of the ATCA's capabilities. 
Conversely, the VLA has dedicated 
telescope operators who observe fo r you. 
I wish I could do m ore of the observing 
myself though. I think learning is not 
just about accumulating information; 
it's also about the process of getting that 
information. I could go away and read all 
the how-to manuals about the telescope and 
its data products, but un til I actually see the 
telescope work, and reduce the data myself, 
I will not truly understand it. 
I feel like I'm at the tail -end of the 
generation of astronomers that gets to 
actually play with telescopes. Hands-on 
observing is fast becoming obsolete. 
W hat will happen to the next generation 
of astronomers who write proposals for 
telescope time' We're always going to have 
people churning out good, solid science. 
But is anyone going to have the expertise to 
S 6 I N AT U RE I VO L 4 90 I 11 OC T OB E R 20 1 2 
© 2012 Macmillan Publishers Limited. All rights reserved 
com e up with somethi.ng truly innovative? 
Unless you are directly involved in the 
building and commissioning of a new 
telescope, do you th ink you can rea lly 
understand it enough to design creative 
experiments that will produce ground-
breaking science? 
Clear skies, 
Milmie 
"The challenge is to 
use our imagination to 
the fullest . " 
Dear Minnie, 
I like your strategy of'playing with 
telescopes' to understand their capabili ties 
and limitations. I think it's important because 
so many great discoveries happen at the very 
edge of capabilities. The am azing story of 
the early galaxies is only barely discernible 
from tiny coloured dots on the Hubble deep-
field images, and it has taken tremendous 
persisten ce on the part of the observers and 
instmment builders to know how to: (a) get 
scientific discoveries from little coloured 
dots; and (b) get better equipment to see 
them more clearly. Similarly, what we know 
of exoplanets has come mostly from people 
who knew how to push the capabilities of 
existing equipment (first), and then pushed 
to get better equipment (after the richness of 
the discoveries becanle apparent). 
You seem a bit concerned that you won't 
be able to learn enough abou.t telescopes 
without touching them. I have that feeling 
too, but I think we are more and more ab le 
to experience things we can't see or touch. 
After all, astronomy is all about things we 
can only see from immense distan ces! I'm 
writing th is on a computer run ning on 
hardware I've never seen, based on quantum 
mechanics that hardly anyone wlderstands. 
At NASA, I'm working on a gian t telescope 
that for years existed only in the imagination, 
along with a few documents and viewgraphs, 
and now two of the four instrwllents are 
delivered and all of the mirrors are finished. 
So, the challenge is to use our imagination 
to the fullest! Hands-on observing is a way to 
build that imagination, but total immersion 
in using something you can't touch still 
works. So to answer your question, yes, I 
truly expect there will be many people with 
the expertise to come up with something 
tmly innovative. We are building the JWST 
so that a generation of people who were not 
even born when itwas started will be able to 
use it for breathtakin g discoveries. 
Fear not, just dive in! 
Jolm 
"What I do object to is 
the complete removal 
of the astronomer from 
the observing and data-
reduction process." 
Dear John, 
I'm really pleased to hear that you're 
not worried about the reduction in 
hands-on observing opportun ities. While 
hands-on observing is something I enjoy 
passionately, I guess I can understand that 
it's not necessarily vital to being a brilliant 
astronomer. 
Having said that, I disagree that 
lmagination can replace the wealth of 
knowledge garnered from sitting in front 
of a terminal and actually being in control 
of a telescope. You say "total immersion in 
using someth.ing you can't touch still WOrks'; 
but is that really true? To use your computer 
analogy, you can read hWldreds of books 
about computers, but you learn most about 
how to use your computer by sitting at it and 
actually playing with it. 
In my last letter, I focused on being 
physically at a telescope to use it. Obviously 
th is is not feasib le for telescopes sud l as 
Hubble and the JWST. But even in these 
circw11Stances, what I do object to is the 
complete removal of the astronomer from 
the observing and data reduction process. 
Radio telescopes are m oving towards a 
model where the astronomer puts in their 
observing request and is then prOvided 
with completely reduced data. I wlderstand 
that this is somewhat necessary due to the 
exorbitantly large sizes of the data sets, but 
I still find it troubling. 
Twenty years ago if you wanted to use 
a telescope, you went to the telescope, 
you observed, and you were responsible 
for reducing your data and analys ing it. 
Nowadays, hands-on observing is becoming 
less prevalent. Science isn't suffering yet 
because the astronomers still retain their 
observing and data-reduction experience. 
But what happens 20 years from now, with 
a new generation of astronomers? I'm not 
convinced that truly innovative ways of 
exploiting a telescope will be possible when 
the telescope users are obi ivious to the 
observation and data reduction processes. 
What are you planning on doing with the 
JWST? Will approved observing programs 
deUver completely reduced data? Will the 
astronomer even know when their proposed 
objects are being observed? 
Clear skies, 
Minnie 
"There is never the final 
answer to anything, only 
the best answer we think 
we have at the time." 
Dear M.innie, 
I agree completely that hands-on 
observing is the way to go when possible. 
There's nothillg like actually touching 
things and studying them in person to get 
acquainted. One wOUlrul't (l hope) marry 
somebody over the internet without meeting 
h.im/her! But as time goes on we all get used 
to ignoring the inner working of thing, 
as long as they are reUable. Hardly anyone 
even knows how a car works dlese days, or 
even suspects dlat it has perhaps a hundred 
microprocessors running Uttle dedicated 
tasks. So we get to concentrate on top- level 
issues, like where to go and how fast. I think 
modern astronomy has go tten to that point 
too - we have software packages with 
mi.lJjons of Unes of code, and we trust that 
somebody ha made them work righ t. And 
we have observatories widl complexities 
d1at are completely hidden from the user 
most of the tinle. Of course, the sceptical and 
cautious user (a real scientist) will not believe 
evelything in the users' manual for either 
a telescope or a software package, and will 
find a way to test every important feature, 
otherwise we will have a lot of non-science. 
I th.ink dle real break' through science will still 
come from people who push the capabilities 
of these tools beyond their design limits and 
test what happens. T hat will take familiarity 
with deSign, and lmagination to pictme what 
cannot be seen. 
About JWST, there's no such th ing 
as completely reduced data from any 
ob ervatory. We do expect that the 
observers will receive data already 
converted into units of astronomical 
brigh tness, according 
to dle best cal ibration 
information and 
algorithms we have. 
But if an object is 
very fain t, it wi U 
have to be observed over a long period of 
time with m ultip le exposures that have 
to be combined; the process of doing the 
combination is not so sinlple, and the 
cautious observer may want to do it h.im/ 
herself. But that's stu'! a very long jwnp 
from data gathering to interpretation of 
the objects way out there - that remains 
the observer's remi t. And there is never 
the final answer to anything, only the best 
answer we think we have at the tim e. And 
yes, the astronomers will know when their 
proposed objects will be observed. (Smal.l 
caveat: we are setting up the telescope to 
have a Uttle autonomy, so if an observation 
cannot be completed in sequence, the 
telescope will automatically go to the next 
one on its list.) 
I find it very exciting to know of the 
discoveries made by people working far 
from my own specialties. And once in a 
while a conversation occurs that starts a 
new field of research , just from asking a 
question about something that is obviolls 
to one person but not to anodler. We have 
dark matter in astronomy dlat i a total 
mystery. But there is a form of dark matter 
in genetic material too, and just lately it was 
announced that it is extremely lmportant: 
the dark matter between dle genes is 
actually millions of digita l swi tch es. I don't 
know when a brea.kdlrough like dl at for 
dark matter and dark energy will occur for 
ast ronomers. But why not? And in another 
area of astronomy, suddenly we know that 
there are as many exoplanets as there are 
tars, dlat small ones are very abundant, 
and that many have been expeUed into 
space and have no star ally more. 
So I think one of the most interesting 
ways to phrase a question in science is: "If 
X happens, then what?" What do you think 
are interes ting questions? 
All dle best, 
John 
To see this conversation continue online, visit 
Lindau. nature.comllindaulonline dialogue 
11 OCTOBER 20 1 2 VOL 490 AT U RE S7 


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