SaberTail
I read their preprint[1] and they did a thorough job. They
investigated a number of the things I'd suspect if I were
looking for mis-reconstructed events or weird
backgrounds.So it's certainly interesting!That said,
particle physics history is full of 3 sigma particle
"discoveries" that disappeared with more data. They're
collecting more, so hopefully we'll learn more in a few
more years.[1]
https://lz.lbl.gov/wp-content/uploads/sites/6/2026/08/LZ_P
re...
|
> matthewdgreen
This sort of thing is really useful for helping people
to understand what the purpose of scientific
publication is. It's not about presenting finished
products to society, it's more like a Discord where
you communicate new findings with other authors. Often
the reason for a communication is because you found
something weird, and you want other people to know
about it so they can help you confirm or rule it out
as bad data. People shouldn't feel gunshy about this.
(My field even has a conference for failed results,
CFAIL.) I like to highlight examples of this stuff,
because I see so many angry online comments when a
paper turns out to be "wrong" or doesn't replicate.
|
> > stouset
Yep. Publishing like this gives a heads up to
those operating similar observatories to keep an
eye out for similar events. And it gives a nudge
to theorists that might help them start looking in
a more fruitful direction, appropriately caveated
that it may be a statistical fluke.
|
> > xaxbxcxdxe
People who stare down noise to see the truth.
|
> > megagpt2
They were - in the past. I imagine that right now,
Discord is their Discord.
|
> > irishcoffee
You have accurately described a email mailing
list. Where in the value-add here?
|
> > > EthanHeilman
> You have accurately described a email
mailing list. Where in the value-add
here?Pre-prints are basically a mailinglist
where you post your paper prior to peer
review.The value over a simple mailinglist
is:1. Stable URL and citation to enable other
work and discussions to cite and reference
it.2. Versioning of the paper, allowing
updates to be made without having mail out the
paper, while allowing everyone to find all
prior versions3. Host for a PDF and data that
might be quite large4. Centralized searchable
long term archive of scientific papers5.
Scalability, arxiv gets 30,000 submissions a
day, no one wants to receive 30,000 PDFs in
their inbox everyday
|
> > > gus_massa
No so wrong. The oldest journals started as
smailing list
:)https://www.scientificamerican.com/blog/info
rmation-culture/...
|
> > > ajkjk
You think that people's findings should be
communicated by email? that their email chains
are what should go into the permanent record
and be cited and printed out and included in
journals and such?would you include all the
quoted text in the reply-alls, or is that too
much?
|
> > > > tokai
Have you never seen a 'personal
correspondence' reference?
|
> > > > > evanb
Yeah but no matter how hard I look I
never seem to be able to read anyone
else's email. Maybe OpenAI's upcoming
models can help me find those
references.
|
> > > > > ajkjk
the fact that they are sometimes
communicated by email doesn't mean
that the best way to communicate them
is by email. Personal correspondence
references are specifically terrible
as references since you can't go read
them...
|
> > > > tomrod
That's how Linux is built.Science has too
many threads to do it successfully though
|
> > > > > Charon77
> would you include all the quoted
text in the reply-alls, or is that too
much?Only quote the relevant part and
reply to it, just like this very
comment.And Linux has a large mailing
archive of various lists and threads
that are searchable and available to
everyone and get this: free access
|
> > > > > > ajkjk
The linux developers' mailing
lists are not producing anything
like scientific papers...
|
> > > > > > bdamm
Kind of arrogant no? Linux kernel
development mailing lists are
producing something immensely
valuable with a much clearer
impact on economic indicators than
your average scientific paper.
Comparing them is hard, but it's
patently absurd to say there's
nothing being produced compared to
scientific papers.
|
> > > > > > ajkjk
Dunno who you're arguing with, I
didn't say they didn't produce
anything of value. I said they
aren't producing scientific
papers. Conversations are not like
papers. The scientists have
conversations (sometimes on
mailing lists!) as well. The
analog to scientific papers in the
Linux world are... scientific
papers. And the occasional essay
on the mailing list, which---get
this---would be more valuable to
humanity if it was subsequently
reproduced as a paper with
references and explanations and
the like.(Notwithstanding the
absurdity of academic publishing,
of course.)
|
> > > colechristensen
Instead of reading everybody's spam or having
to have a centralized body decide who gets to
send messages to the mailing list, journal
editors filter which things are worthy of
publication and in which journal such that
readers don't have to wade through garbage or
uninteresting results.
|
> > > matthewdgreen
If I had the email address of every researcher
in my field, I would never send a mass email
to them describing my latest goofy idea. I
would, however, send my latest goofy idea to a
conference with those same reviewers (if I
felt it was technically appropriate and
correct.)
|
> > > > XorNot
I mean we use to have newsgroups which
basically implemented this.Which of course
is the point: it is in fact quite similar
to a mailing list, just with some extra
protocol surounding it to make it
manageable.So the attempted snark about it
up thread is stupid.
|
> > > > > IAmBroom
Still inaccurate.A paper has a
(semi-formal) structure, including
TITLE, AUTHORS, and the all-important
ABSTRACT.Email guarantees none of
those.
|
> > > baq
It's a special purpose mailing list. The value
(your motivations for asking notwithstanding)
is in the special purpose, not in the mailing
list.
|
> smueller1234
Or this[2] 2007 Science paper on ultra high energy
cosmic ray source candidates ("anisotropy") that we
had to retract because significance started dropping
almost the day the paper was approved.It was a
fascinating experience as a junior member to follow
the collaboration internal conversation and
investigation on this, because a lot of extremely
principled scientists were clearly deeply worried
about losing their hard earned reputation. In the end,
I am convinced that we were simply unlucky.[2]
https://arxiv.org/pdf/0712.2843
|
> > WarmWash
Reminds me of the FTL neutrinos too, where the
scientist where pretty much "hey, something is
wrong, can you help us figure it out?" and the
general public were the ones screaming "OMG!
Physics is dead!"Then when it comes out as
measurement error, the public is all "Damn these
scientists are all hype machine clowns..."
|
> > > dguest
Unfortunately it wasn't just the public: it
caused so much uproar within the experiment
that two of the highest ranking members
resigned their posts [1].I was a bit dismayed
at the reaction within the physics community.
Experiments absolutely do need to follow
procedures like blinding and careful internal
review (especially before the data
unblinding), but you can only spend so long
designing the analysis before you unblind, and
there are opportunity costs to cross checking
everything. In an optimized community
experiments will inevitably make mistakes. And
once you unblind, it does no one any good to
sit on an anomalous result forever.[1]:
https://www.nature.com/articles/nature.2012.10
371
|
> > > pfdietz
That was a fiendish thing to debug; if I
recall correctly it was a slightly and
intermittently defective connector.
|
> > > dd8601fn
I'm fine with that. Put it at the feet of pop
science blogging.I'm less fine with the time
and resources spent on mouse models. They
already know you'd get the same utility from a
magic 8 ball, but they do it anyway.
|
> > > > gus_massa
Mouse models are useful to discard very
bad ideas. There was a recent experiment
to use bacteria to kill cancer
https://news.ycombinator.com/item?id=46306
894 They tried like 40 bacterias in vitro,
then like 9 in mice, and only 1 was useful
in mice and they will continue only with
that, perhaps in humans. Anyway, as you
suggest, there is a high chance it will
fail.Also, you can do nasty stuff to mice
that would never be allowed with humans.
In that experiment they injected cancer
cells in mice with a bad inmune system, so
they could get like 90 mice with cancer
and run the experiment in a short time. No
ethical committee would approve that in
humans.
|
> > > > IAmBroom
Your claim seems to be that testing
medicines in animals is useless, because
"everyone knows it's not going to
work".Congratulations. You've just reduced
all of medical science to the Tuskegee STD
experiment.
|
> > logdahl
Wow haha, that is a lot of authors! Never seen
this before!
|
> > > kens
Most horrifying is a 2014 Science paper on
Ebola with 58 authors, 5 of whom died of Ebola
before publication.
https://www.science.org/content/article/ebolas
-heavy-toll-st...
|
> > > thiagotomei
The ATLAS-CMS joint Higgs boson mass
measurement paper has close to 6000 authors:
https://doi.org/10.1103/PhysRevLett.114.191803
I think the final COVID consortium report has
something like 30k authors.
|
> > > smueller1234
As another comment points out: that's nothing
compared to high energy/particle physics!The
Pierre Auger Observatory certainly is a large
collaboration for the astroparticle physics
domain though. It's a big international
collaboration.Quick anecdote: my name (S
Mueller) is not on that paper's author list
because we had a rule that you had to be in
the collaboration for a year before getting
authorship. You stayed on for a year after
leaving. Very reasonable! At the time I was
nonetheless a bit bummed about missing out on
the big Science paper. I guess I'm on the
retraction though ;)
|
> > alexpotato
> we had to retract because significance started
dropping almost the day the paper was
approved.It's stories like this that raise my p(we
are in a simulation).
|
> GuB-42
> That said, particle physics history is full of 3
sigma particle "discoveries" that disappeared with
more data.The idea is that because 3 sigma means a
~1/1000 chance of the thing being explained by random
chance, 1 in 1000 experiments will produce a bogus 3
sigma result, and we do many thousands of experiments.
|
> > adgjlsfhk1
and also because a result always has the caveats
of "if we did our experimental design and math
right". A 1/1000 rate of experimental/code design
errors will double the number of incorrect 3 sigma
results.
|
> derektank
Are there any other candidate particles besides WIMPs
that the observation could be from, assuming it's a
real signal?
|
> > SaberTail
In one sense anything that passed all their
background rejection is a WIMP. To interact with a
nucleus through so much matter, it's not
interacting electromagnetically. The main
candidate for a strong force interaction would be
a neutron, and they did a lot of work to model
that and eliminate it as a background. So
definitionally it would be a WIMP.They were pretty
model agnostic in what they were looking for. They
modeled and simulated a number of different ways a
WIMP could interact with normal matter. If this is
a discovery, more data will be needed to figure
out the nature of that interaction and how it fits
into particle physics.But there's always a chance
it's something completely new, or some extremely
rare manifestation of things we already know
about, but have never seen before. And even if it
is WIMP, it may not be the right type of WIMP
(wrong mass, or wrong interaction strength) to
explain cosmological dark matter.
|
> > > imglorp
If neutrons are on the list, how are they
ruled out from a random decay event emitting
particles, from some mineral in the
surrounding rock?
|
> > > > physicsdude
The detector from which data is taken to
do this analysis contains 7 tons of liquid
xenon. It is inside of a larger detector,
which contains hundreds of tons of water
and more than 10 tons of a scintillator.
One of the functions of that outer
detector is to absorb neutrons and other
infiltrates coming from the rock.When
doing this kind of thing, the analysts
will plot the rate of events as a function
of "distance from the outer surface" and
confirm that it decreases, and in this
case "is 0" inside of the detector used
for analysis.But keep in mind that all
statements are made statistically, so it's
not that the event _can't_ be an external
neutron, but that it is _very_ unlikely to
be.
|
> > > > Nevermark
The experiment is set up to make any
already understood interactions some
combination of easy to identify or
extremely improbable.
|
> > > > SaberTail
They have a lot of shielding for the
detector, and also if there were a
significant source of neutrons they'd
expect to see other evidence, both in the
detector and in the separate "veto"
detector that surrounds the main
detector.That's not to say it can't be a
neutron, but it would be surprising if it
were.
|
> antonvs
The mainstream TV news report that I saw about this
ended with a comment about how we should continue to
fund this detector. Made me wonder if the nature of
this release involved forces other than purely
scientific ones. Apparently funding has already been
cut for the successor to the LUX-ZEPLIN detector.
|
> > physicsdude
Particle physics is not a particularly large
community. There is a hand-countable number of
experiments like this, and the folks working on
each of them know the folks working on each of the
others. The collaborations executing each
experiment are comprised of scientists employed by
multiple independent institutions, both public and
private, typically across national borders.
Internally, the collaborations have a democratic
structure with individual researchers acting as
institutional representatives serving in what is
essentially a parliamentary structure to make
decisions. The software to determine results is
always public within the collaboration and
reviewed well in advance of making any truly
public disclosure like this.Culturally, an attempt
to intentionally distort or misrepresent data to
suggest a result like this would not be tolerated.
You can imagine a bad actor writing a
single-author paper with fakery, but a
collaboration at this level is inherently critical
of itself and everyone holds each other
accountable.But mistakes do happen. Exciting
results or hints of exciting results can appear
due to well-intentioned researchers making
convenient mistakes which get glossed over for
psychological reasons and then add up to appear as
something significant. You can read about
"blinding" (which is mentioned in the paper) to
get a feel for the techniques researchers employ
to not only guard against fabricating results
intentionally, but even unintentionally.
|
> > > IAmBroom
The small pool also lends itself to a lack of
unbiased reviewers. If everyone in the
community is more-or-less tied to the
research, who can best objectively test it,
from a blinded POV?
|
> > > > physicsdude
That is a great point. I'm not sure if I
fully understand your question, but I'll
comment on both "testing," meaning doing
the analysis, and "reviewing," meaning
peer review.The point of "blinding," as I
mentioned it before, is to guard against
biasing the result due to choices made by
analysts while figuring out how to compute
their final answer. Part of that is just
psychological --- if an analyst _knows_
that the data is obscured, for lack of a
better term, in a way such that they can't
believe a signal that they see (for
example --- that's just one way to blind),
then they won't feel any emotion or
excitement about things they encounter
while constructing the analysis, because
they know what they're looking at isn't
real, and that helps them to maintain
objectivity. It's also common to have
multiple independent analysis teams for
something like this --- they know that
they'll have embarrassed themselves if
they don't all get the same result both
before and after unblinding, which
provides pressure to maintain
objectivity.As far as review goes ---
there are physicists who believe in dark
matter, and there are physicists who don't
believe in dark matter. But all particle
physicists and nuclear physicists use the
same core technical and statistical
methods. For a result like this, there
will be a few "core analysts" who do the
analysis, typically graduate students and
postdocs. Their advisors review their
work, through the lens of making sure that
they are doing so sanely. The
collaboration will also establish an
internal review committee to comb through
the documentation and software which
produced the result, not necessarily
trying to disprove what they found, but
really looking at it critically. Once it
gets to a journal, they'll get reviewers
who may be biased for or against the
result, and who may or may not work
directly on dark matter detection, but who
can all assess the methodology by which
the result was obtained. That's probably
the best we can do with humans involved.
|
> > > antonvs
I'm not suggesting distortion or
misrepresentation of the published result. The
actual preprint is quite clear on the nature
and limitations of the result, and there's no
reason to think that what they're reporting
didn't happen as described.However, the
context here is that the DOE has already
paused funding for the experiment's successor,
XLZD, for an unspecified amount of time which
realistically, is probably going to depend on
the next US presidential election. At the same
time, the DOE encouraged the LZ project to
develop scenarios for continuing to operating
beyond its current end date of 2028.Now,
here's what the NBC Bay Area report I
mentioned[0] ended with:> "All the more
reason, they say, to keep these machines
running. [...] They'd like to keep the
machines running, they wanna keep doing this
research, they're applying for funding now, so
fingers crossed, we'll have more updates on
this [...]"The media attention this received
was not the organic result of some journalist
noticing the preprint or the talk at TeVPA in
Japan. There was a major wave of synchronized
official press releases, coinciding with the
TeVPA talk, from Berkeley National Lab[1],
Brown University[2], SLAC[3], Brookhaven[4],
Stanford[5], University of Sydney[6], and
others including UMass Amherst and Imperial
College London.Now, these institutions are all
involved in the collaboration somehow, so it
makes sense that they would coordinate press
releases for a major result. The question is
whether this result warrants such treatment.
It's a single event at 2.6 sigma global
significance. Promoting it in this way was a
choice, and I'm pointing out that it seems
quite possible - in fact I'd say extremely
likely - that that choice was made with the
funding situation top of mind.[0]
https://www.youtube.com/watch?v=bf3aW0xTEEc[1]
https://newscenter.lbl.gov/2026/09/01/lz-sees-
surprising-res...[2]
https://www.brown.edu/news/2026-09-01/lz-dark-
matter-results[3]
https://www6.slac.stanford.edu/news/2026-09-01
-lz-sees-surpr...[4]
https://www.bnl.gov/newsroom/news.php?a=123133
[5]
https://news.stanford.edu/stories/2026/09/dark
-matter-detect...[6]
https://www.sydney.edu.au/news-opinion/news/20
26/09/03/lz-ex...
|
> > > > physicsdude
Thanks for clarifying, and my apologies if
I came off as argumentative --- what you
_are_ suggesting makes sense and is a
reasonable thing to wonder about.But I
don't see anything particularly strange or
coordinated is happening. From the
collaboration's perspective, it's quite
stressful having this event. They've
already unblinded, so it would be
unethical to do anything other than report
what they found. If they publicize it and
it's a mistake, then that's a big blow to
their credibility. But if they withhold it
and it's real, then they miss making the
discovery and/or bias their future
analyses on larger datasets without
disclosing that to the community. So they
are in a tough spot, and are safest to
just tell the world what they saw.This is
getting media attention because it would
be a big deal to the general public if
this ends up being a real. Someone in the
field wouldn't claim that it's real, but
the possibility is catnip to folks looking
for a sensational headline. That the press
releases are synchronized in time is
because the result was just released right
now and they're all doing their
commentaries right away --- for something
like this, each institution independently
negotiates a release with the local
researchers who are involved. They all
promise to wait until the result is
officially released, out of respect for
the scientific process, like you say, but
the different institutions aren't
coordinating with each other. They're just
all respecting their own researchers.Is a
2 or 3 sigma fluctuation worth a lot of
press? Personally, I don't think so. But
we don't know if it's a fluctuation yet,
and no institution is going to pass on
having made it clear, if this does turn
out to be real, that they were
involved.All that being said: I would very
much like these folks to continue to
receive funding. They are professional and
do excellent work, as demonstrated here.
|
pizzathyme
> it's far too early to claim a discovery, physicists
warn..."How do you even make sense of one event?" muses
Tom Shutt, a particle astrophysicist at SLAC National
Accelerator Laboratory and co-founder of the LZ project.
"We just decided we should publish and think really,
really, really hard about what that event could be."Very
hard to manage jumping the gun by reporters. Sounds like
they saw some new data. No idea what it is.Looking forward
to the follow up.
|
petcat
> The detector lurks 1480 meters deep in the Sanford
Underground Research Facility, in a former gold mine in
South Dakota.Glad to see such things getting re-purposed
instead of just sealed off and abandoned.
|
parineum
> If the new result is real, more signals should emerge
soon. LZ researchers have already collected three times as
much data as they used in the paper.It sounds like this
implies they've seen 3x more events but it seems like they
would have said that if it were the case. Have they just
gathered more data about the single event or is this 4
separate events they're talking about?
|
> SaberTail
Detectors like this work on exposure. They're always
on (except for calibration and maintenance), waiting
for events to happen. This paper was written with 2.8
tonne-years of data. That is, 4.7 tonnes of liquid
xenon for a little mmore than half a year. The
detector has 7 tonnes, and the 4.7 number reflects
cuts they made on parts of the detector that either
they don't understand as well, or have higher
backgrounds.As they better understand the detector,
they can use more of that mass. They have data from
it, but they just didn't use it. And they're always
collecting more data, too, as time passes.So the 3x is
saying they have something like 8.5 tonne-years of
data.
|
> > lofaszvanitt
Hm, they have 7 tonnes of Xenon. Events detected
all around in the matter, but the PMTs can
localise where the event happened. So they can
virtually segment parts of the detector where they
are sure all the outside effects are understood
and taken care of.
|
> IsTom
If this anything like CERN detectors, they get amounts
of data so vast that they have to discard almost all
of it to be even able to record it. Depending on
heurestics you use to discard data you might be
discarding what you are looking for and after
adjustment will get some new interesting events, but
still actually processing the candidates might take a
long time.
|
> > physicsdude
This raises what is (I think) an interesting
question. CERN is a collider, so they are _trying_
to produce lots of stuff, and they do (lots and
lots of stuff). They can't write it all to disk,
and most of it isn't interesting enough to try.The
work being done here falls into the category of
"low background physics" --- they aren't trying to
produce anything, and actually put quite a bit of
effort into doing the opposite, by removing all
sources of particles (e.g. sourcing materials free
of radioactive contaminants, physically cleaning
all surfaces and purifying all fluids involved,
etc).So the detector, if built properly, is fairly
quiet, and you try to write as much data to disk
as you can (e.g., if something even
fairly-potentially interesting happens, you save
it). Then when you analyze the data like this, you
ignore the majority of what you've got --- only a
teeny fraction makes it into an analysis of this
caliber.
|
> > > thiagotomei
I think this description is essentially
correct.
|
> gus_massa
They collected x3 more hay, and they still have to
processes it and try to find any needle mixed with
it.Hopefully it the new data may have 3 additional
events, or perhaps 2 or perhaps 4 or perhaps 10 or
perhaps... Or the reported event may be false event
caused by a lucky coincidence, and they may find 0
additional events.
|
> evanb
Whether or not they've "seen" 3x more events is a
little bit of a tricky question, because while they
may have captured 3x the data exposure (see sibling
comments) experiments often operate blinded to the
data. They can develop their analysis scripts, play
out various different scenarios via Monte Carlo
simulation, and get their whole pipeline working
without the bias of actually seeing how each change in
algorithm alters the outcome for the real data.Then,
at some point, they freeze their pipeline, "open the
box", run the analysis on the real data, and report
what they find. But they can only "open the box" once
per exposure, after that you can worry that human bias
can creep in.
|
naasking
They detected a single weird event, not necessarily a
particle.
|
scotty79
Why couldn't it be just a weirdly energetic neutrino
originating from the neighborhood of some black hole?
|
> physicsdude
At some level, it could be (and that would be an great
discovery as well!). It's a question of probabilities:
it's unlikely to be any of the things that we already
know about, but that doesn't mean that it's something
new. Unlikely things happen --- infrequently. As
stressed in the article and elsewhere in comments,
more data should elucidate what is going on. That's
the difficulty of these kinds of searches: there is
one event, and we can't make clear, confident
statements about one event.
|
> hershkumar
I actually saw one of the authors present the data
yesterday, one of the audience comments was indeed
that this could be explained by an astrophysical
neutrino striking the detector (all other neutrino
sources have energy thresholds much lower than the
detected data), but the data on astrophysical
neutrinos is sparse (in part why detectors like
IceCube exist), so I believe the argument is that the
chances that an astrophysical neutrino would strike
the detector is negligible.
|
> > scotty79
Thank you very much for this first hand info. One
might argue that chances of theoretical particle
existing and showing up are at least as
negligible.
|
> > > hershkumar
I think the WIMP interaction process via the
models they tested and the data on
astrophysical neutrinos from other detectors
gives at least several(?) orders of magnitude
of separation in the rate at which each would
strike the detector. Of course this would not
fully rule out the possibility that it is a
stray neutrino.
|
> procflora
Based on my very amateurish skim of this and a related
paper, maybe so? They simulated the neutrino
background as solar and cosmic ray atmospheric
sources, so any source with a different energy
distribution is perhaps a possible explanation for the
event, I think.But probably more likely is for this to
have been a particularly energetic event in the tail
of one of the known sources of neutron recoil
detection they did model. More events needed!
|
gwbas1c
I think it's cool that there's still unconfirmed
hypothesizes, and still unexplained phenomena in the
science that's investigating these hypothesizes.I hope
this turns into a real discovery about something; but even
if it's an equipment malfunction, hopefully it's a lesson
that can be turned into improving the detector.
|
> BurningFrog
Astronomy/Physics is overflowing with unexplained
physics phenomena these days.Especially after JWT
started looking deeper into the early universe.
|
> strogonoff
The moment there are no more unconfirmed hypotheses
you can assume something is wrong with sciences. All
provable models (theories, explanations) that we have,
or could have, are by definition wrong or incomplete.
|
> > tsimionescu
I'm guessing you're alluding to Goedel's
incompleteness theorem, but that really doesn't
apply to physics. It's a statement about certain
properties of formal systems - basically it tells
us that for any formal system that's at least as
powerful as arithmetic, it's impossible to prove
every statement that is true in that system.This
doesn't in any way mean that you can't in
principle describe with perfect accuracy with such
a system, in a provable way, every aspect of
physics. Sure, you might need a theorem that can't
be proved and be stuck because of that, but it's
not a given. Physics certainly doesn't depend on
all possible statements in that formal system to
accurately model the real world, and so Goedel's
theorem can't prove that the subset that physics
needs might not be all probable.
|
> > > birdland
I don't think Gödel is necessarily what is
meant here, there are very good information
theoretical(and other) reasons you can never
describe a system with truly perfect accuracy.
The map has to be become the territory for
genuinely perfect accuracy.
|
> > > > retsibsi
> The map has to be become the territory
for genuinely perfect accuracy.Why
couldn't the territory be losslessly
compressible?
|
> > > > > narnarpapadaddy
The currently accepted answer to that
is "the territory appears to be
randomized" (quantum mechanics)
|
> > > > > > retsibsi
Makes sense, but is it relevant to
the upthread claim that "All
provable models (theories,
explanations) that we have, or
could have, are by definition
wrong or incomplete"? (Not being
rhetorical and snide here, I'm
curious and aware I may be missing
something.)If reality has
irreducible randomness (an open
question afaik), and we're talking
about theories and explanations
(so we're not necessarily trying
to describe the actual state of
every particle in the universe,
but only the rules governing their
interactions), couldn't we have a
complete, correct theory that was
much smaller than the universe and
contained terms for the random
elements?There would always be the
possibility that it would turn out
to be wrong, but it could be
complete and correct, so it seems
like the original claim must
depend heavily on the word
'provable' and not on the
impossibility of describing a
system via a map smaller than the
territory.edit: but also, surely
'the territory is randomized' is a
contingent physical fact, and not
a necessary truth of information
theory. Until we know for sure
that there is irreducible
randomness, we can't know that the
information content of the
universe (including the actual
state of all particles at all
times) isn't losslessly
compressible, right?
|
> > > > > > narnarpapadaddy
The "elements for randomness" are
carve-outs for the parts of
territory the map can't contain.
The more granular the map, the
larger relative proportion that
falls into that set. Nobody can
predict the layout of my basement
from a globe of the world.We know
with a high degree of certainty
the universe contains things we
can't predict or observe, see
Bell's Theorem."Truth" doesn't
exist outside reality. There's no
substrate to hang it in.
Information theory is likewise a
subset of the territory, part of
the universe, not apart from it.
For these things to exist
independently, you need something
other than or bigger than the
universe to put them in. If such a
thing existed, sure, from that
perspective maybe a lossless
compression could exist. But
that's a metaphysical argument.
|
lordnacho
So you have 7 tons of Xenon as the detector, hoping that
some dark matter will bump into a nucleus. How do you
exclude other effects?
|
> SaberTail
To start with, they do a lot of work to eliminate
radioactive backgrounds in the materials they're
using, and they put the detector deep underground to
shield from cosmic rays.Additionally, when a particle
interacts with the nucleus, the ratio of how much
energy ends up as scintillation light versus
ionization is different than when a particle interacts
with an electron, which is most of the background
processes.Then, whatever is left, they try to model
using known processes. After all that, there's one
event that they can't account for. And that's what the
news is about.
|
> > gus_massa
I agree. Moreover, I'm not sure if it's the same
team, but in a similar experiment while removing
all the other effects, they discovered that Xenon
124 is radioactive, but the half life is super
long and no one had seen it before.
https://xenonexperiment.org/observing-the-rarest-d
ecay-proce...
|
> > > cogman10
Makes me wonder if all atoms with 2+ nucleus
elements (protons and neutrons) are
radioactive but the halflife is so far out as
to make something we'll never detect.
|
> > > > cwmma
Probably not, they have a pretty good
handle on why atoms decay, to the point
they can predict some to be radioactive
before it's actually observed to be (like
Bismuth-209).Also even if something is
REALLY REALLY long lasting, you can still
check for the halflife by observing enough
of it, they've been able to rule out
proton halflives under 10^34 years (the
universe is on the order of 10^10 years
old) but by observing enough protons (like
say 50,000 tons of water) you would expect
at least some to decay.
|
> > > > > cogman10
> they have a pretty good handle on
why atoms decayOh, they actually
don't. Radioactive decay, AFAIK, is
still an open physics mystery. We know
it happens, we don't know why, what
causes it, or if there even is a
cause. We can predict factors that
make it more likely.> to the point
they can predict some to be
radioactive before it's actually
observed to be (like
Bismuth-209).Right, but Xenon 124
wasn't predicted to be radioactive
which is what makes it fascinating. It
shows holes in what we can predict as
being radioactive which is what makes
me wonder about everything being
radioactive but the timetable is too
far out.
|
> > > > > > cwmma
I don't actually think Xenon-124
being radioactive was a surprise.
All the publicity related to
observing the decay for the first
time is phrased around 'hey we
observed something that's very
rare' not 'hey this thing happened
we didn't expect to happen'.Which
seems to point even more towards,
scientists have a pretty good
handle on which ones are
radioactive.
|
> > > > > > mr_mitm
Where is the mystery? Any system
can spontaneously transform into a
new state with a probability
greater than zero unless some
conservation law prevents it. In a
sense it's just quantum tunneling.
|
> > > > > > baq
The mystery is the details, not in
that it happens at all. Feel free
to submit a paper if you have all
the answers.
|
> > > > > > mr_mitm
Can you be more specific? I
believe quantum mechanics explains
all of radioactive decay. Unless
the GP meant that QM is
mysterious, I don't understand the
problem.
|
> > > > > > baq
I mean questions like could you
predict the decay of Xe-124
correctly? AFAIK theory
overestimates the rate
|
> > > > > > mr_mitm
Quantum Chromodynamics, path
integrals, and what other
mechanisms you need for deriving
the half life are extremely
complicated, especially for that
many particles, so of course it's
hopeless without approximations,
which can be wrong, or are even
wrong by definition. But the fact
that it's prohibitively hard to
solve the equations for such
complicated systems doesn't
indicate a gap in our
understanding. You don't even have
to go to xenon, this is already
the case for tritium.
|
> > > > marcosdumay
There's just no way deuterium is
radioactive, unless hydrogen is
radioactive too.
|
> > > > > gus_massa
Some theories predict that protons
decay, but the half life is like 1E31
or 1E35 years (compare to the Xe124
that has a half life of only 1E24
years). All experiments so far to
measure the proton decay have failed,
anyway.
https://en.wikipedia.org/wiki/Proton_d
ecayI don't remember anything specific
about deuterium, and the method that
Xe124 uses is not available, and I
can't imagine a razonable alternative
method, so my guess is that deuterium
is as stable as protons.
|
> > > > > > gus_massa
Too late to edit: Some conclusion,
wrong number. The correct half
life of Xe124 is 1E22, instead of
1E24.
|
> > > pfdietz
Those double beta decays are also interesting
because they can probe whether the neutrino is
a Majorana particle.
|
> > > vintermann
That's a pretty cool discovery in its own
right.
|
> > > > jakzurr
Wow! That's in
https://en.wikipedia.org/wiki/Xenon
now.Xe-124, half-life 1.1 * 10^22 years.
That's crazy.
|
> > martinpw
Yeah, it's funny, for experiments like this you
spend 90% of your time modeling and subtracting
noise, and 10% analyzing the signal that results.
Had the same experience in X-ray astronomy. 3
years building a detailed model of all the sources
of noise, then subtracting it out and finally
starting on the science.
|
> > > wuliwong
I worked a little on the Virgo interferometer,
I would say about 99.9% of the work on those
types of detectors is limiting and subtracting
noise. ( ≧ᗜ≦)
|
butlike
I'm out of touch and 5 years old, so please someone
explain to me, but I thought the galaxies were bound
together by divets in spacetime based on their mass
dictated by the Higgs field. Now its dark matter binding
the galaxies together?
|
rajaravivarma_r
I always wondered if it would happen in my lifetime. Hope
it turns out to be something interesting (AKA) dark
matter.
|
advisedwang
> Such behavior could require dark matter to be more
complicated than just a single new type of particle. For
example, the dark matter particle might have some internal
structure, like an ordinary atom, so it would only
interact if hit hard enough to excite it to a higher
energy internal stateI get a little shiver imagining that
the dark matter might be something like ordinary atoms.
Imagine that other 85% of the universe could have its own
parallel atomic table, chemistry, even some kind of life
utterly alien to us?
|
> isomorphic
I've heard this referred to as a "dark sector", or
"hidden
sector":https://en.wikipedia.org/wiki/Hidden_sectorThe
scary thought is that, were it true that there is
voluminous richly-interacting dark matter, we would be
the actual dark sector.
|
> > kstrauser
"Imagine a universe, like ours, overlapping ours,
except where some of its matter spontaneously rips
itself apart, and other matter can be mashed
together if you squeeze it hard enough." "That's
nightmare fuel! Fortunately it's probably
impossible, so far as we can tell."I can imagine
other scary thoughts, though. Ever read any
Warhammer lore?
|
> > > clarionbell
Good news: we have discoverd FTL! Bad news:
the ship came back *wrong*.
|
> > vld_chk
On this the same line of thoughts, so far we have
0 proof that all dark matter is _the same_. We
observe gravity effects but IIRC they very little
tell us about their own homogeneity. We very well
could have a few parallel sectors, one of which is
ours.
|
> evanb
Maybe there are even dark scientists trying to explain
the missing 15% of the universe! One such scientist,
easily pegged as a kook, suggests a model with SU(3) x
SU(2) x U(1) gauge symmetry, with one sector
spontaneously broken by a scalar field, and three
flavors of fermions to allow for enough CP violation
and masses spanning 10 or 11 orders of magnitude.
|
> hyperhello
It's possible that there could be an entirely
different charge mechanism that works exactly like
ours but they don't interact at all; but the whole
premise of dark matter is that it doesn't seem to have
any self-interaction outside of gravity.
|
> > gizmo686
The premise of dark matter is that it is something
with gravity that does not otherwise interact with
any of our detectors (e.g. "normal" matter); or
that any such interactions are weak enough that it
is plausible we have not noticed.By itself, that
does not exclude the possibility of dark matter
having other interactions which do not interfere
with our detectors.
|
> > > XorNot
But it does bound it: if dark matter has
self-interactions then the apparent
distribution would be different. Regular
matter forms stars and galaxies and all the
structures we see because it can
self-interact.Since where we see dark matter
mass shadows we don't see structure formation,
what self interaction it may have must be
very, very limited.
|
> > > stouset
Our observations are much more consistent with
a form of dark matter which does not
self-interact, or which does so incredibly
weakly.Don't ask me how or why, but this is
essentially the universal (pun intended)
consensus amongst cosmologists.
|
> > > > terminalbraid
That doesn't rule out "dark matter having
other interactions which do not interfere
with our detectors" Dark sector theories
which include other dark particles or new
particle interactions are not
controversial amongst cosmologists in this
space. For example there's a whole area of
study around "dark photons" which would
mix with our photons and interact with
dark matter.
|
> > > hyperhello
I guess so. If you could sort of measure the
dark matter distribution, there might be a
structure under it, but strictly speaking
isn't it limited to saying it's not at least
likely to emit light but does have mass.
|
> > > marcosdumay
It's very hard to explain the gravitational
halo around the galaxies if your dark matter
can interact with itself. If it interacted
like normal matter, it would have a
distribution similar to the gases, and not
spread way into intergalactic space.
|
> T-A
You might like this old paper
then:https://arxiv.org/abs/0903.0660v1
|
hirshi
How many years until we've discovered "everything"?
|
> jesse_dot_id
Probably never. We've only mapped like 29% of the
seafloor, actually explored like %5 of it, and we've
barely pierced the earth's crust.
|
> > kypro
I never understood why people cite this as a
demonstration for how little we humans understand
about our world.The reason we haven't mapped the
seafloor is because why would we? It's like
arguing we know nothing about biology because
we've only sequenced the genome of a fraction of
humans or something. It's not that we can't do it,
the reason we haven't done it is because there's
no good compelling reason to do it. What do we
expect to learn from mapping 100% of the sea
floor?As for the parents question - "How many
years until we've discovered "everything"?"I think
we may be fairly close to knowing everything we
can know and it's quite reasonable to assume we're
now comfortably on the tail end of the S-curve of
physics discoveries. I hope I'm wrong of course.
|
> > > jesse_dot_id
I cite it because we're barely scratching the
surface of our own world, which is one of a
potentially infinite number of worlds that is
encapsulated by the word "everything."Why
would we map the seafloor is an insane
question that immediately invalidates all
other opinions that you may have,
unfortunately. The human embodiment of that
meme with the pickaxe guy walking away from a
diamond strike if only he had swung once
more.It's so hubristic to assume that our
generation is the one that will discover the
answers to everything.
|
> > > > kypro
> I cite it because we're barely
scratching the surface of our own world,
which is one of a potentially infinite
number of worlds that is encapsulated by
the word "everything."I think maybe I was
assuming the parent was referring
specifically to physics discoveries while
you were assuming that they were asking
more broadly about how many years until
we've discovered everything
discoverable?Unless you are actually
arguing there's likely lots of physics
discoveries to be made because humans have
only photographed a fraction of trees on
the earth, or mapped a fraction of the
seafloor, or sequenced only a fraction of
the genomes of known species?
|
> > > ourmandave
I'm a complete layman but it seems like we've
got a long way to go and history will look
back on us like we do on Newtonian
Physics.Just given dark matter and energy,
things the standard model doesn't answer, and
our evolving tools (e.g. Grace telescope,
etc.).
|
> > > > kypro
To expand a little, my prediction is based
on the fact that we can already explain
the vast majority of physical processes
with extreme procession. The things we
can't explain tend to be very small, very
large or very quick. But there's almost
nothing in our day to day lives that we
can't explain anymore.This means that
today to make new discoveries we tend to
have to invest huge sums of money and
build experiments that we'll increasingly
struggle to scale significantly beyond.
For example, maybe humans could just about
build something 10x the size of the LHC if
we really wanted, but 100x seems
near-impossible. Maybe we can build
slightly larger telescopes, but again,
this is becoming harder due to the scale
we're already working at.So while I agree
there's probably lots of physics out there
to discover, the physics we humans are
actually likely to be able to discover is
rapidly diminishing. And the physics which
is likely to revolutionise our daily lives
is presumably even smaller more due to
scale and energy levels where mysteries
remain.But ultimately who knows, this is
just my opinion - an opinion I'm being
downvoted for because apparently HN
discussions these days are a place for us
circlejerk around the consensus view
rather than discuss differences in
opinion.
|
> vasco
You can know all the whats and hows and still have no
clue about why
|
> sph
May I strongly suggest you to read Asimov's short
story The Last Question for an
answer.https://users.ece.cmu.edu/~gamvrosi/thelastq.ht
mltl;dr: likely as long as the lifespan of the
universe.
|
amemi
Not well informed on the topic- but the title made me
think of the recently launched Roman Space Telescope.The
difference: LUX-ZEPLIN, which is underground, is waiting
to detect a dark matter particle itself. On the other
hand, NGRST seeks to observe the effects of dark matter.
|