
Giant Molecules Exist in Two Places at Once in Quantum Experiment - jonbaer
https://www.scientificamerican.com/article/giant-molecules-exist-in-two-places-at-once-in-unprecedented-quantum-experiment/
======
mirimir
Damn, it wasn't so easy to find the article, because TFA doesn't explicitly
provide author names, even. But the link in the image title led to Fein et al.
(2019).[0]

So what I'm curious about is how far apart those "Two Places at Once" are. And
if I'm understanding Fig. 2 correctly, it's _large_. That is ...

> Fig. 2 | interference data. a, Counts as a function of the transverse
> position of the third grating with a sine-fit (solid black line) yielding a
> visibility of 25 ± 3%. The optical grating power was 1.2 W for this single
> scan. Counts are dark-rate-corrected and normalized to the control
> measurements.

... with peaks at ~200 nm, ~430 nm, ~680 nm and ~900 nm.

But a 25 kDa molecule is only ~4 nm in diameter.[1]

That's amazing!

0) [https://sci-
hub.tw/http://dx.doi.org/10.1038/s41567-019-0663...](https://sci-
hub.tw/http://dx.doi.org/10.1038/s41567-019-0663-9)

1)
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3055910/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3055910/)

~~~
gmueckl
Thank you!

Rant: Not linking to the source article is a crime conmited by many outlets
trying to report on science. I do not understand that practice. It is even
worse when the researcher's institution does this in a public press release
(MIT is consistently guilty of this). Are these people afraid that their
watered down "explanations" are so wromg that even a cursory glance over the
paper will show this?

Some news sites such as Ars Technica provide the links. They even have
agreements with major publishers that allow them to bypass paywalls and
provide their readers with links to the the published full text as well.

~~~
benologist
There's a dated document that leaked at the start of the decade called The AOL
Way that sheds a lot of light on these tactics -

[https://www.slideshare.net/cartercole/the-aol-way-leaked-
pla...](https://www.slideshare.net/cartercole/the-aol-way-leaked-plan)

External links are used for SEO and generally reserved for partner-websites or
their own properties to recirculate traffic. Here we have an article reposted
from space.com to scientificamerican.com that only links to nature.com and
livescience.com. Future US owns space.com + livescience.com, and Springer
Nature owns scientificamerican.com + nature.com.

~~~
nerdponx
It doesn't need to be a link. A citation at the bottom of the article would
suffice.

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aazaa
The original paper, fortunately linked in the article, is quite readable:

[https://www.nature.com/articles/s41567-019-0663-9](https://www.nature.com/articles/s41567-019-0663-9)

I was expecting it to discuss the largest species previously shown to
demonstrate an interference pattern, but unfortunately there was none.

Other points of note:

Regarding the choice of molecule, and specifically fluorination:

> An intense neutral beam of intact molecules is a prerequisite for our
> experiments, but soft neutral volatilization and post-ionization of complex
> molecules is an outstanding technical challenge. While matrix-assisted laser
> desorption and electrospray ionization are useful tools for molecular
> analysis, the charged beams they pro- duce are incompatible with the
> stringent dephasing requirements of interferometry. Continuous effusive
> thermal beams, on the other hand, suffer from thermal fragmentation for
> masses beyond a few kilodaltons. This can be overcome via fluoroalkyl-
> functionalization of the molecules, which adds mass, reduces the
> polarizability-to- mass ratio and increases volatility

The group sees another factor of 10 increase in the ability to measure
interference:

> With advances in beam sources for biomolecules and metal clusters26,27,
> techniques to cool the particles below 80K (refs.28,29), and refined
> grating26 and imaging technologies30, our experiment is scalable and will
> push matter-wave interference and macroscopicity tests by another order of
> magnitude24

The Coriolis effect was corrected at least in part mechanically rather than
purely computationally:

> Compensation of the Coriolis effect is critical to obtaining high-visibility
> interference fringes in LUMI. By tilting the gratings, we introduce a
> gravitational deflection that opposes the Coriolis shift ...

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toxicFork
Please correct me where I am wrong, I have only studied quantum physics as a
hobby.

I dislike this description of things existing in two places at once, this is
because I believe that objects exist in one place, then they move to the next
place.

The interference pattern only highlights the probability of where the particle
will be when it's next observed, or "where it moved to". The object does not
interfere with itself, it's the probability wave that is interfering with
itself, and the wave is something separate from the object but is related to
it.

The particle does not exist anywhere between its current position and the
next. It does not travel in a "linear" or other way, if at time t it was at
position 0 and at time tNext it was at position 1, at time tNext*0.5 you
cannot assume it was at position 0.5, or both "position 0.5, slightly higher
up" and "position 0.5, slightly lower down" at the same time.

In another way, in my mind, the object exists here, then it exists there, but
it did not exist at the time between here and there, unless you happened to
have observed it. Then of course "there" would be where you have made the
observation because you have given it something to interact with.

I guess my issue is, at what moment does the article say that it exists in two
places at once? Are they inferring this from the fact that there is an
interference pattern?

To quote: "[1] Every particle or group of particles in the universe is also a
wave—even large particles, even bacteria, even human beings, even planets and
stars. [2] And waves occupy multiple places in space at once. [3] So any chunk
of matter can also occupy two places at once."

I guess my problem is with [1] "is also a wave". I think that "there is a wave
related to the object" but not "the object IS a wave". Then [3] does not
follow.

~~~
toxicFork
To go further, I have a colleague who says there are actually no particles,
only waves interacting with other waves. I am trying to get him to make a
proper thesis out of this but he is busy trying to earn money to support his
family. If there are any theories about this, please link them in the thread!
It sort of resonates with what Richard Feynman has been demonstrating in some
of his lectures but I have not been able to find the right keywords to search
the internet, or the best way to ask scientists.

Problems of hobby scientists...

~~~
xcodevn
It is called Quantum Field Theory.

~~~
toxicFork
Thanks!

~~~
Sharlin
And it has been _the_ mainstream quantum theory for decades. Nothing new. But
physics doesn't concern itself with what "actually exists", only which models
work the best. Whether fields or particles are ontologically more basic is a
question as of now relegated to the realm of metaphysics. Some physicists have
opinions in one way or another, others just subscribe to the "shut up and
calculate" school of thought.

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scotty79
> Because physicists already knew that electrons had mass and were definitely
> particles ...

I think that evidence for existance of particles is pretty old and should be
reconsidered. I think we 8should more carefully treat the data that convinced
physicists that matter is particles, before they knew matter is a wave. Maybe
it's counter productive to percieve matter as made of particles with particle
qualities (what are those? pointlike, with specific (even if unmeasurable)
momentum, position energy).

Maybe momentum, position and energy is not something 'particles' have all the
time. Maybe it's just something they manifest only while interacting.

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im3w1l
> That’s big enough that the researchers had to account for factors like
> gravity and the rotation of the Earth in designing the beam emitter

Will this provide us with insight into how gravity and the quantum world
relate?

~~~
ojnabieoot
I have not read the paper, am not an expert, and can't judge with 100%
reliability - but my understanding is no, I don't think an experiment of this
type will necessarily provide the insight into a quantum nature of gravity.

The effects described here are purely Newtonian - in particular, the earth's
rotation and gravity are the same "kind" of impact, just an F=ma force which
deflects the beam of molecules in the same manner that gravity deflects a
stream of water out of a garden hose or the earth's rotation deflects a
Foucault pendulum. In general I think I quantum gravitation experiments would
require very low-mass particles in a very high-mass gravitational well: high-
mass particles on Earth will be dominated by Newtonian gravity and quantum
effects will be extremely difficult to detect.

The relation this does give insight on is between Newtonian and quantum
physics - the fuzzy boundary between determism and randomness - which is
itself interesting, but also better understood. Perhaps a more precise
measurement may reveal that the gravitational deflection is significantly
more/less than expected from classical gravitation in a way that can only be
explained with a new quantum theory, but that is quite speculative and almost
certainly not supported by the evidence in this particular experiment.

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rafaelvasco
Soon, things that are today considered fantasy and disregarded as mysticism
will become science facts, just as electricity and magnetism were alien things
a century ago. In the end we will realize that every myth comes from a true
source. Everything can be made to be, once you put enough energy to make it
manifested; I have absolutely no doubt in my mind about this, since I've seen
and read things that are well beyond from what is common knowledge;

------
ycombonator
Listen to this episode where Sean Carroll talks about Superposition of larger
objects [https://podcasts.apple.com/us/podcast/52-many-quantum-
worlds...](https://podcasts.apple.com/us/podcast/52-many-quantum-worlds-sean-
carroll/id1265002699?i=1000444468426)

------
Altheasy
The scientist who find the point where super position stops will get the Nobel
price for sure, I could give you a hint, it is less than my cat, I'm sure it
never been in two places at once (Schrödinger is right about his cat too)

~~~
nabla9
Superposition is not stopping as far as we know it.

Cat typically weighs 3,6 – 4,5 kg. De Broglie Wavelength of 4 kg cat moving
1×10^-10 m/s is 1.7×10^14 m.

You cat is in many places at once, those places are just very close to each
other.

~~~
bobm_db
Something I don't quite understand about quantum mechanics and the MWI... At
the point the atom passes through the diffraction grating, it has a quantum
superposition. According to MWI, reality has "branched", right?

Then the two realities interfere with each other to form the probabilistic
pattern at the detector. So, according to MWI, reality has "merged" again?

If we accept the mulitiverse idea of MWI, doesn't that mean at some point
particles aren't able to marge with their branched-reality versions?

~~~
evanb
The "at some point" doesn't have to do with time. It has to do with the rest
of the wavefunction of the universe. If the atom becomes entangled with
everything else (in fact, a single quantum-mechanical spin suffices) the two
branches become orthogonal and the interference terms from 'merging' vanish.
We say the wavefunction 'decohered' when it becomes too complicated to see how
to reverse this effect---as more and more particles get involved it becomes
hopeless.

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Ceezy
It s a PROBABILITY of being at the same position and not a position per say.

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hi41
Since the molecule of 2000 atoms exists in two places, it doubles the mass.
Doesn’t this break the law of conservation of mass and energy. Can someone
please explain how this is possible.

~~~
gewa
From a quantummechanic standpoint its wrong to say, that its at two places at
once. I really dont like the Headline. Superposition means, that it didnt
decide for one of the two possible states, and so these both exist in
superposition.

~~~
heavenlyblue
Can you say it’s moving between two places with an infinite frequency?

~~~
chousuke
My own understanding of QM at this point is that it's sort of wrong to think
of anything being exactly anywhere, ever.

The way I intuit it, QM systems seem to be described by their wavefunctions
sort of the same way a bunch of sine waves together makes music. You could
have a QM system that is spatially (mostly) at X, represented by a wave
function, or at Y, represented by another, but the third option, a
superposition, is the combination of those two wave functions.

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freecodyx
i feel like my brain is too abstract to accept the idea of something can be at
multiple places at once, feels like a chess game, in which every possible move
is already known, you only chose one at a time, and thus you decrease the
possibilities toward your goal, and there is no go back.

~~~
ozmodiar
I have trouble with this especially since I’m not sure if the language they’re
using is just creating a misunderstanding.

My example is quantum entanglement, which judging from a lot of sci-fi, people
think means you literally have the same particle in two places, and changing
it in one place changes it instantly in the other. Really it just breaks
entanglement and you now have two different particles (so you can’t use it for
FTL communication, hear that sci-fi authors?). It took me awhile to understand
that, and I’m sure I have similar misunderstandings about this.

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mrfusion
So could you have these two places be inside and outside a black holes event
horizen?

~~~
wcoenen
No. That would allow objects to gain energy by quantum tunneling, which (as
far as I know) quantum mechanics doesn't allow.

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Stay_frostJebel
Finally they can get started on quantum superposition human teleporters. I
want to see Neptune but I want to be home by dinner.

~~~
Koshkin
Here it is:

[https://solarsystem.nasa.gov/planets/neptune/overview/](https://solarsystem.nasa.gov/planets/neptune/overview/)

