Does a Champagne Cork Really Break the Sound Barrier?
Every New Year's Eve the same physics fact does a lap online: popping champagne is a sonic boom in miniature. A few science-news outlets have already caught the sloppy version of that claim and corrected it — it's the escaping carbon dioxide, not the cork itself, that goes supersonic. That correction is real. What we wanted to know was whether the specific numbers behind it hold up once you read the underlying research directly instead of the articles about it. Mostly, they don't agree with each other.
The claim
Popping a champagne bottle launches the cork fast enough to break the sound barrier — commonly illustrated with a headline speed (50 mph is the figure that recurs most) and framed as a genuine sonic boom.
Source trail
Two separate research lineages get cited for this, usually without being told apart. The older one: physicist Friedrich Balck at what is now Clausthal University of Technology built a measuring rig for a German TV segment in December 2008 and has kept adding to his own physics pages since. The newer one: two independent peer-reviewed fluid-dynamics papers, Liger-Belair, Cordier and Georges in Science Advances (2019) and Wagner, Scheichl and Braun in Physics of Fluids (2024), both used high-speed imaging to separate the cork's own speed from the speed of the gas that follows it out of the bottle. A widely repeated eye-injury figure from the American Academy of Ophthalmology (AAO) runs alongside both, cited by nearly every article on the topic — often incorrectly.
What's confirmed
- Every direct measurement of the cork itself, across three independent sources, puts it at a few dozen km/h — nowhere near supersonic. Friedrich Balck's own physics page, fetched directly (biosensor-physik.de and its companion page, checked 2026-08-25), records an experimental measurement of a cork covering 5.5 metres in 0.48 seconds — 11 m/s, about 40 km/h (25 mph) — and a separate theoretical calculation of "etwa 60 km/h" (about 60 km/h, 37 mph) at 3 bar with no friction assumed. Clausthal University's own press office, via a cached description of its December 2008 release (checked 2026-08-25), independently states the same 11 m/s figure and attributes it to Balck's own apparatus. Separately, Liger-Belair, Cordier and Georges' peer-reviewed paper (Science Advances 5(9), eaav5528, published 20 September 2019, DOI 10.1126/sciadv.aav5528, read via its PubMed Central full text, checked 2026-08-25) states the cork itself "is flying with a velocity (≈15 m s⁻¹)" at bottle temperatures of 20°C and 30°C — about 54 km/h (34 mph). Wagner, Scheichl and Braun's 2024 paper (Physics of Fluids 36, 056111, built on their December 2023 arXiv preprint 2312.12271, checked 2026-08-25) gives a comparable figure of about 20 m/s (72 km/h, 45 mph) and calls it explicitly "comparatively low."
- Both peer-reviewed papers agree the escaping gas, not the cork, is what goes supersonic — but they don't state the same speed for it, and one commonly repeated figure for it doesn't appear in the paper it's credited to. The arXiv abstract for the Wagner/Scheichl/Braun paper, fetched directly (checked 2026-08-25), states that once the cork clears the bottle opening "the jet rapidly assumes locally supersonic speed" with "a complex shock pattern" including Mach discs — but the abstract itself gives no number. A science-news summary of the same paper puts a figure on it: up to 400 m/s (about 1,440 km/h, 895 mph). For the 2019 paper, our own direct read of the PMC full text (checked 2026-08-25) found only a qualitative statement — that the headspace-to-ambient pressure ratio "much exceeded the critical ratio needed for the CO2/H2O gas mixture to reach Mach 1" — with no specific top speed stated in the text we could access. Multiple secondary science-explainer sources nonetheless attribute a specific figure to this research: "nearly Mach 2," roughly 2,400 km/h (1,524 mph). We could not locate that number in the primary paper itself.
- Guinness World Records' own listed "fastest champagne cork" has nothing to do with popping a bottle by hand. Its page, fetched directly (checked 2026-08-25), states: "The fastest velocity a champagne cork has ever been subjected to is 11.5 km/second (7.1 miles per second)" — about 41,400 km/h (25,700 mph) — achieved in the X2 expansion tube at the University of Queensland. The X2 tube is a real hypersonic research facility independently documented on the University of Queensland's own engineering pages (checked 2026-08-25), built to simulate spacecraft re-entry conditions — not a bottle being opened. Guinness's own page names no date and gives no methodology beyond the facility name.
- The American Academy of Ophthalmology's own current page states a cork speed of 34 mph, not the 50 mph figure most articles attribute to it. Fetched directly from aao.org (checked 2026-08-25): "A Champagne cork can fly up to 34 mph as it leaves the bottle — fast enough to shatter glass." The page cites no study for this number. A currently ranking site, fetched directly (checked 2026-08-25), instead attributes "around 50 mph" to the AAO — a figure that does not appear on the AAO's own page as we read it.
What isn't
- No primary source we found states a cork speed of "100 mph," the round number that shows up as an "outlier" in at least one aggregator's own accounting of the claim. The highest cork figure in any primary source we reached is Balck's own theoretical 100 km/h (62 mph) — in kilometres per hour, not miles. We think a km/h-to-mph mix-up is the likeliest explanation for where a "100 mph" figure would come from, but we did not find a specific article that makes that substitution, so this is our own inference, not a confirmed transmission trail.
- The two peer-reviewed papers' gas-speed figures don't reconcile against each other, and we could not resolve why. ~400 m/s (Wagner et al., per secondary summary) and "nearly Mach 2" / ~2,400 km/h (Liger-Belair et al., per secondary summary, unconfirmed against the primary text) are substantially different numbers. Different bottle temperatures, different measurement points in the jet, or simple secondary-source imprecision could each explain the gap; we did not have access to enough of either paper's full methodology to say which.
- Our own arithmetic doesn't match one site's stated multiple either. 400 m/s against the standard speed of sound at 20°C (about 343 m/s) works out to roughly Mach 1.2. One science-news article citing the same 400 m/s figure describes the gas as moving at "over 1.5 times the speed of sound." Neither that article nor the paper it summarizes states what air/gas temperature its speed-of-sound reference uses — a colder gas at the nozzle would have a lower local speed of sound and a correspondingly higher true Mach number, which could close some of the gap, but we could not confirm that this is what happened.
- We could not independently verify the University of Queensland X2 tube's champagne-cork test beyond Guinness's own page. The facility itself is real, per the university's own pages, but we found no UQ press release describing a champagne-cork test specifically, only Guinness's own listing.
Verdict
The core correction already circulating is right: the cork itself is not what breaks the sound barrier. Three independent measurements — one physicist's own rig, and two separate peer-reviewed papers thirty years apart in method — put the cork at roughly 40 to 72 km/h (25 to 45 mph), nowhere near supersonic. It's specifically the escaping CO2 gas that goes supersonic, confirmed by both peer-reviewed papers. But almost none of the specific numbers riding along with that correct headline hold up under a direct read of the sources they're credited to: "100 mph" traces to no primary source we could find, a widely repeated "50 mph" doesn't match the American Academy of Ophthalmology's own current page, and the two peer-reviewed papers' own gas-speed figures — 400 m/s versus "nearly Mach 2" — don't match each other either.