What if the measurement problem isn't about explaining how the classical world emerges from the quantum world...
...but about what happens when quantum systems interact with something that's already classical?
Turns out, the collapse postulate + Born rule emerge!
scirate.com/arxiv/2510.0...
🧪⚛️🧵1/5
Great work! It seems that the approach is similar to the stochastic collapse, but the nonlinearity here is effective, due to the feedback loop between quantum and classical, is that right? Would that still cause any observable features due to this effective nonlinearity, apart from possibly heating?
What a difference a decade makes! Announcing the clearest #GravitationalWave detection ever #GW250114
youtu.be/2XmZ8-XQ9jU
📓: doi.org/10.1103/kw5g...
🔭🧪⚛️☄️ #O4IsHere
New masses in the stellar graveyard plot, showing astronomical observations of black holes and neutron stars. The number of gravitational-wave observations of black holes is overwhelming. The plot is arranged to look nice, the horizontal axis has no meaning, but the vertical one shows masses. We have a significant range of masses from about 1 solar mass to over 200 solar masses for our largest merger remnant. New out today is a neutron star black hole binary GW230518_125908, as well as a lot of binary black holes.
Results from the first part of our fourth LIGO @egovirgo.bsky.social KAGRA observing run are out today!
We're pleased to share the largest catalog of gravitational-wave observations with more discoveries of black holes and neutron stars
📰 arxiv.org/abs/2508.18082
🔭🧪⚛️☄️ #GWTC4
That's a wrap!
We've had hundreds of talks from scientists from all across the world over the last two weeks, but it's finally time to say goodbye.
On behalf of everyone on the organising committee, thank you for coming!
#GR22Amaldi16
We're not really sure. There are many theory predictions: like stochastic background from phase transitions in the early universe, inflation, etc. From the compact objects, these could be light primordial black holes or exotic stuff like Q-balls, gravastars or boson stars.
We'd need to adapt calibration and data acquisition techniques, but we could already add this in LIGO or GEO600! Why not? That would be fun!
Have a look: www.nature.com/articles/s41...
We compute the sensitivies of different detectors and show that all modern detectors hare quite comparable to the dedicated high-frequency detectors. We could also build small-scale detectors which have good sensitivity in a broad band.
In fact, the sensitivity of the detectors depends on the point on the sky from where the signal is coming from. Usually, we assume the signals to come from zenith. And for such signals we're indeed not sensitive above a few kHz.
Not the case for other points on the sky (like on the image here)!
Published in Scientific Reports, we explore the sensitivity of the detectors at high frequencies. Funny enough, it's actually been known for decades, but not to the broad community, and many colleagues assumed that detectors are limited to a few kHz.
www.nature.com/articles/s41...
Gravitational-wave detectors currently measure signals at around 10-1000 Hz. It is not widely known, but they are also quite sensitive to GW signals at much higher frequencies — up to GHz. We don't know whether there are signals there, but wouldn't that be fun?! We wrote a paper about that!
🧪 🔭
A presentation at a scientific conference. The speaker is standing at a podium. The slides are projected behind them. The title of the slides is "Supporting early career researchers".
Today at #GR24Amaldi16, the GWECS team is presenting on supporting early career researches.
GWECS is Gravitational Wave Early Career Scientists - find out more at: gwecs.org
The story of our first discovery of two merging black holes
youtu.be/0lUxk8yxaNY
A documentary by Kai Staats
#BlackHoleWeek 🔭🧪⚛️
LVK March 2025 Poster Prizes: Lorenzo Pompili, Nicole Khusid and Audréanne Matte-Landry
Our recent Collaboration meeting saw lots of exciting science being shared. Congratulations to our Poster Prize winners for their excellent presentations:
🧑🏫 Theory: Lorenzo Pompili, MPI Gravitational Physics
🧑💻 Data analysis: Nicole Khusid, Stony Brook
🧑🔬 Experiment: Audréanne Matte-Landry, Montréal
Thank you!
An excited awardee is giving a talk at the prize award ceremony
I'm really happy to have been awarded the Rudolf Kaiser Prize in experimental physics! I got it for my experiments enhancing optical force sensors with quantum squeezed light generated inside the sensors themselves.
Feeling motivated to get back to work and do some more fun science!
Saturn's outer moon system viewed from the north pole of Saturn. Moons orbiting in clockwise (retrograde) orbits have red-colored orbits while moons orbiting counterclockwise (prograde; in the direction of Saturn's spin) are colored blue. With so many irregular moons occupying the same region and intersecting each other, the irregular moon system looks like a donut-shaped vortex surrounding Saturn. Each of the 128 new moons is highlighted in the diagram with a white point representing their location, and a brighter-colored orbit. Previously-known moons of Saturn are included in the diagram, but are colored darker. The regular moons of Saturn are colored turquoise and the outermost regular moons (Titan, Hyperion, and Iapetus) labeled with their name. At the lower left corner are scale indicators to help visualize the scale of Saturn's irregular moon system. A small gray circle at the left left corner is shown to represent the diameter of the Earth-Moon orbital distance. A linear scale bar is labeled "10 million km" (6.2 million mi) to give a standard distance.
View of Saturn's irregular moon system, tilted at an angle to show the toroidal belt-like shape of the system. Each moon is labeled with their names in turquioise. Red orbits = retrograde direction, and blue orbits = prograde direction. Turquoise curves closer to the center are orbits of Saturn's regular moons.
Side view of Saturn's irregular moon system, tilted at an angle to show the toroidal belt-like shape of the system. Red orbits = retrograde direction, and blue orbits = prograde direction. Turquoise curves closer to the center are orbits of Saturn's regular moons. The irregular moons of Neptune (dark green) are also visible in the background to the right of Saturn. The horizontal red line protruding right of Saturn is the orbit path of Saturn.
I spent almost 2 hours painstakingly copying the orbits of all 128 Saturnian moons from the announcement MPEC and reformatting them for visualization...
Behold, here are the orbits of ALL 128 MOONS OF SATURN. This isn't just a moon system—it's a literal asteroid belt around Saturn! 🧪🔭☄️
That's a good point! My thinking was that the set of 3 detectors is synchronized "two-way" with light, but then detects GWs arriving uniformly from various directions, and then any anisotropy would appear as deviations from this "average" two-way value. But I'm really out of my depth here...
I had made Microsoft Quantum aware of issues before publication of this latest Nature paper (which uses it tune up their devices).
Since they seem to not care, I have make these issues public.
In short: The topological gap protocol and all claims based on it are flawed.
arxiv.org/abs/2502.19560
That's a good point, I've also been reading up on it since, but it's not so clear in the case of a different carrier (GWs)...I mean, the clock synchronization in this case is directional (the detectors are in different places), but the GW is not. Thus we kind of show the isotropy already.
...alternative theories with direction-dependent speed of light, but that's a curious application of GWs, I think. Unless the logic is flawed, of course :)
[1] journals.aps.org/prd/abstract...
we have two independent measurements: the speed of gravity is equal to c, and the one-way speed of light is equal to the speed of gravity. Thus, one-way speed of light is equal to c! To within ~1% or so, whatever the current statistics would be. Not sure if that's enough to exclude...
From statistics of GW events, as it's shown in [1], we can independently estimate the speed of gravity to be equal to the speed of light to within ~1-2%. That is based on the first 50 detections. Now we have seen over 200 events, and I'm sure new statistics will pin this down well below a %.
So...
...found that the speed of gravitational waves equals the speed of light up to the ~8th decimal digit. But that in itself doesn't tell anything about the speed of light!
Luckily, we have another way to measre the speed of gravity: using the delay in arrival of a GW to different detectors.
...I think :)
Curiously, I haven't found this argument anywhere in the literature. So I want to argue that we actually have measured the one-way speed of light. Using...gravitational waves!
In 2017, we saw GWs and light coming from the neutron star merger GW170817. From this measurement, we...
You might've heard that we don't actually know the real speed of light. The reason is usually given to be that all our experiments actually measure two-way speed of light (e.g. to a mirror and back). It could be that the speed of light changes on the way there and back. It's no longer true!
🔭🧪
Well, the quantum computing stocks went up 15% with this press release, so there's that...
Here is a short thread about the review itself:
bsky.app/profile/mkor...
And the journal issue is here, some interesting papers there (including a few on future gravitational-wave detectors).
www.mdpi.com/2075-4434/13/1
A few days ago the publisher told me that my recent review was selected for the cover, and I was to provide a nice engaging picture, asap. I've never drawn nice enganing pictures, so after a night with procreate, youtube and lots (LOTS) of coffee, the best I could do was this, please be engaged :D
This is a mega-thread of all Microsoft problems related to topological qubits.
NOTE: I skip the numerous news reports and press releases, this thread is for serious _scientific_ and procedural materials
First retraction: Quantized Majorana Conductance, from Nature
www.nature.com/articles/nat...
