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David Neilson

@dtneilson.bsky.social

100 followers 230 following 33 posts

Physicist and Optical Communications. Bell Labs

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Physics 39%

Political science 17%

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David Neilson @dtneilson.bsky.social · 4h

That’s longer than Jansky was alive 😢

Reposted by David Neilson

Robert “The Bobby Yaga” McNees @mcnees.bsky.social · 4h

The Very Large Array, part of The National Radio Astronomy Observatory, was formally dedicated #OTD in 1980.

It was renamed the "Karl G. Jansky Very Large Array" in 2012. Happy 45th birthday, VLA! 🧪 🔭 📡

An image from the movie “Contact” shows Jodie Foster’s character listening to headphones in front of a line of VLA radio dishes that stretch off towards the horizon. One of the dishes is my shaggy golden doodle Linus, wearing a post-surgery cone around his head.

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Reposted by David Neilson

Robert “The Bobby Yaga” McNees @mcnees.bsky.social · 14d

Happy 120th birthday, special relativity!

Albert Einstein introduced special relativity in the paper "On The Electrodynamics Of Moving Bodies," published in Annalen der Physik #OTD in 1905. 🧪 ⚛️ 🔭

Manuscript: onlinelibrary.wiley.com/doi/abs/10.1...
English: www.fourmilab.ch/etexts/einst...

A black and white photo of Albert Einstein, around age 25, sitting at a desk. He is a wearing a flannel suit and resting his right arm on the desk. Einstein is looking to the left of the photographer in this posed photo.

The first paragraph of the paper, in German. Translated to English is reads:

It is known that Maxwell's electrodynamics—as usually understood at the present time—when applied to moving bodies, leads to asymmetries which do not appear to be inherent in the phenomena. Take, for example, the reciprocal electrodynamic action of a magnet and a conductor. The observable phenomenon here depends only on the relative motion of the conductor and the magnet, whereas the customary view draws a sharp distinction between the two cases in which either the one or the other of these bodies is in motion. For if the magnet is in motion and the conductor at rest, there arises in the neighbourhood of the magnet an electric field with a certain definite energy, producing a current at the places where parts of the conductor are situated. But if the magnet is stationary and the conductor in motion, no electric field arises in the neighbourhood of the magnet...

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Reposted by David Neilson

Ethan Siegel @startswithabang.bsky.social · 17d

Finding good information is hard.

A study done on 2.5M pregnant women who took Tylenol during pregnancy showed no adverse fetal effects.

However, pregnant women with untreated fevers had increased fetal risk of:

Neural tube,
Heart,
And abdominal wall,

Defects.

Plus cleft palate and more!

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Reposted by David Neilson

Henry Legg @henrylegg.bsky.social · 21d

On a side note: Whilst writing my data analysis lecture this week, I discovered that the spurious correlations on tylervigen.com now come with AI explanations!

They're brilliant: Here's the explanation why GMO corn growth in North Dakota correlates with Google Searches about headaches.

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Reposted by Siegfried Hekimi, David Neilson

Marc Veldhoen @marcveld.bsky.social · 21d

With the viral season upon us, the debate over vaccination will flare up again.

It remains strange to watch: the advantages are many, well established, and increasingly better supported by evidence, including benefits against non-communicable diseases.
1/10

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Elizabeth Jacobs, PhD @elizabethjacobs.bsky.social · Sep 4

RFK Jr. rolled out that old chestnut again about how healthy Americans were in the 60’s, so here’s a fact check.

In 1965:

-42% of American adults smoked; it’s 11% now.

-The infant morality rate was 24.7/1000; it’s 5.6/1000 now.

-Overall life expectancy was 70 years; it's about 77 years now.

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Reposted by David Neilson

Paul Guinnessy @paulguinnessy.bsky.social · Aug 13

I love Christine's writing

"Those of us who have been lucky enough to live in countries that have had several decades without a war can cling on to our fantasy that we are in some way in charge of our destiny, that peace is our right and the norm."

"Peace is not the norm." I think we forget that.

Beauty and the Beast

The game we're all caught up in

christinapatterson.substack.com

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David Neilson @dtneilson.bsky.social · Jul 28

“Give me your tired, your poor,
Your huddled masses yearning to breathe free,
The wretched refuse of your teeming shore.
Send these, the homeless, tempest-tost to me,
I lift my lamp beside the golden door!”

Reposted by David Neilson

Robert “The Bobby Yaga” McNees @mcnees.bsky.social · Dec 1

The mathematician Nikolai Ivanovich Lobachevsky was born #OTD in 1792. He developed a non-Euclidean geometry that shows up in areas ranging from relativity to the designs of M.C. Escher. (1/n) 🧪 ⚛️ 🔭

Portrait: Lev Kryukov (wikimedia)

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Reposted by Bertrand Guillaume, David Neilson

LIGO Scientific Collaboration @ligo.org · Jul 14

The LIGO Virgo KAGRA study of #GW231123 was posted to the arXiv today, and is free to read

arxiv.org/abs/2507.08219

Data are available from the GW Open Science Center

gwosc.org/eventapi/htm...

#OpenScience #OpenData ☄️

$arXiv preprint GW231123: a Binary Black Hole Merger with Total Mass 190-265 M⊙ On 2023 November 23 the two LIGO observatories both detected GW231123, a gravitational-wave signal consistent with the merger of two black holes with masses 137+22−17M⊙ and 103+20−52M⊙ (90\% credible intervals), at luminosity distance 0.7-4.1 Gpc and redshift of 0.39+0.27−0.24, and a network signal-to-noise ratio of ∼22.5. Both black holes exhibit high spins, 0.9+0.10−0.19 and 0.80+0.20−0.51 respectively. A massive black hole remnant is supported by an independent ringdown analysis. Some properties of GW231123 are subject to large systematic uncertainties, as indicated by differences in inferred parameters between signal models. The primary black hole lies within or above the theorized mass gap where black holes between 60-130 M⊙ should be rare due to pair instability mechanisms, while the secondary spans the gap. The observation of GW231123 therefore suggests the formation of black holes from channels beyond standard stellar collapse, and that intermediate-mass black holes of mass ∼200 M⊙ form through gravitational-wave driven mergers.$ Figure 7 of the paper showing the inferred masses. The masses are measured to be high, but the exact values depend significantly depending on the waveform model used. These are the most significant systematic uncertainties we have seen so far. New detections are pushing the boundaries of our calculations.

Figure 7 of the paper showing the inferred masses. The masses are measured to be high, but the exact values depend significantly depending on the waveform model used. These are the most significant systematic uncertainties we have seen so far. New detections are pushing the boundaries of our calculations.

Figure 8 of the paper showing the inferred spins. Results again vary between waveform models, but they consistently show high spin magnitudes with some support for misalignment relative to the orbit of the binaries.

Screenshot of from the Gravitational Wave Open Science Center showing spectrograms of the signal (which is short) as well as links to download the raw data.

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Reposted by David Neilson

Jacopo Bertolotti @jacopobertolotti.com · Jul 10

If you did a PhD (in the UK) funded by #EPSRC and are looking for a postdoc position, we (meaning @exeter.ac.uk, not me specifically) have 3 open Postdoctoral Research Fellowships.
All info in the link below.
#AcademicJobs #Physics

jobs.exeter.ac.uk

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David Neilson @dtneilson.bsky.social · Jun 23

"a mote of dust suspended in a sunbeam," Sagan

Reposted by David Neilson

David Phillips @photonphillips.bsky.social · May 30

2 postdoctoral researcher positions are available in the Structured Light Group in Exeter (UK). Project focussed on quantum & classical light control through dynamic complex scattering media (see concept picture). Details are below. Drop me an email if you'd like to know more! 🧪💡

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David Neilson @dtneilson.bsky.social · May 30

John Von Neumann "with four parameters I can fit an elephant, with five I can make him wiggle his trunk"

Reposted by David Neilson

Jacopo Bertolotti @jacopobertolotti.com · May 30

#PhysicsFactlet
Wavefront Shaping is a family of techniques used to control light (or, more generally, a wave) propagating through a scattering medium.

A 🧵
1/

🧪⚛️🎢💡

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Reposted by David Neilson

Optics & Photonics News @optica-opn.org · Apr 15

Researchers at Chalmers University of Technology created a waveguide that can amplify near-infrared light 10 times more than current devices, which could improve #telecommunications and boost medical #imaging.

Read the OPN story: bit.ly/44pXBX5 💡🧪⚛️

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Reposted by Robert Price, David Neilson

Robin Ince @robinince.bsky.social · Apr 5

Put up by Katy Brand today - this is the story over and over again

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Reposted by Olivier Corneille, Hernán Aguirre, David Neilson

Katie Mack @astrokatie.com · Apr 3

Enough internet. Time to cheer myself up by writing about how dark energy will eventually destroy the universe.

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Reposted by David Neilson

Rachael Sirianni, PhD @docsirianni.bsky.social · Mar 15

Our operational shutdown means we are not doing what we normally do bc we don’t have the stability to function. We won’t be testing new chemo drugs. We won’t be developing new biomaterials. We won’t be following new leads. We won’t be doing what scientists do: discovery. No NIH = no discovery

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Reposted by David Neilson

Rachael Sirianni, PhD @docsirianni.bsky.social · Mar 15

We will continue with data collection for a recently funded grant that came from a private foundation. There will be no pursuit of new ideas for now

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Reposted by David Neilson

Rachael Sirianni, PhD @docsirianni.bsky.social · Mar 15

Did you know that science labs work like small business entrepreneurs? Faculty hired on strength of ideas, get some startup $ to last 3-4 yrs. After that is grants- grants pay all our + our trainees’ salaries + scientific work. Funding in this country is frozen. That means scientific work stops

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Reposted by Elliott L. Hazen, Helen Burstin, Tanya Heikkila , and 10 more Elliott L. Hazen, Helen Burstin, Tanya Heikkila, Wolfram Dressler, Shannon M. Monnat, Alex Imas, Lynette Shultz, Yara Mekawi, Ted Temzelides, Andrea Iaboni, David Neilson, Lu Shi, Ward Berenschot

Rachael Sirianni, PhD @docsirianni.bsky.social · Mar 15

This is horrible to post, but I may as well post it. We are essentially shutting down research operations in my group, which is focused on treatments for pediatric brain cancer. I’m a well funded investigator, and there’s no choice. Science can’t function without the stability of NIH

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Reposted by David Neilson

southpaw @nycsouthpaw.bsky.social · Mar 12

A lot of people who got the measles as children died or suffered lifelong disabilities as a result. The measles vaccine was a godsend to worldwide public health, and it’s an absolute scandal that this lethally ignorant dolt has any power over public health.

Logarithmic chart showing the case and death rates for measles in the USA per 100,000 population. The chart maps dramatic near total declines in both over the last century.

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David Neilson @dtneilson.bsky.social · Mar 9

Murray Hill is a current Bell Labs building while the show is set in the old main building in Holmdel … though not the site of the discovery of the Big Bang the article mentions …

David Neilson @dtneilson.bsky.social · Mar 9

Temporal non locality

David Neilson @dtneilson.bsky.social · Mar 6

Maybe a flat lake or sea but getting the right orientation would be difficult

David Neilson @dtneilson.bsky.social · Mar 6

The halo is the exit pupil … image of the input pupil (the hole in the screen) and lateral color is the wavelength depending magnification of the exit pupil.

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David Neilson @dtneilson.bsky.social · Mar 6

No reference. You don’t see it in the real world because the reflector is effectively diffuser as the other version of the system you show.

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David Neilson @dtneilson.bsky.social · Mar 6

Lateral color in the halo … one of the less famous aberrations 😀

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