View source for Comments on "Five Experiments as Hard as Finding the Higgs"

{{Infobox paper
| title = Comments on "Frontier experiments: Tough science &mdash; Five experiments as hard as finding the Higgs"
| url = [http://www.naturalphilosophy.org/pdf/abstracts/abstracts_6464.pdf Link to paper]
| author = [[Zifeng Li]]
| keywords = ''Nature'', extraterrestrial life, chiral molecules, extra dimensions, [[Gravitational Waves|gravitational waves]], the kilogram, [[Speed of Light|speed of light]]
| published = 2012
| num_pages = 1
}}

'''Read the full paper''' [http://www.naturalphilosophy.org/pdf/abstracts/abstracts_6464.pdf here]

==Abstract==

The five frontier experiments published in ''Nature'' are commented item by item: spotting distant signs of life, seeing through the molecular mirror, looking for extra dimensions, catching a gravity wave, redefining the kilogram. It is concluded that the first two experiments are great ideals that are impossible to realize in recent years, the last three are false theories pulling physics into morass.

==Overview==

'''Full title:''' "Comments on 'Frontier experiments: Tough science &mdash; Five experiments as hard as finding the Higgs'". This is a '''one-page commentary''' by [[Zifeng Li]] of Yanshan University on a news feature by '''Nicola Jones''', "Frontier experiments: Tough science — Five experiments as hard as finding the Higgs" (''Nature'' '''481''', 14–17, 2012), which surveyed five experimental goals then regarded as extremely difficult.

Li takes each in turn and delivers a verdict. His conclusion divides them into two groups: the first two are '''worthy but unattainable''' in the near term, while the last three rest on what he regards as '''false theory''' and are therefore not merely hard but pointless.

The piece is brief and declarative rather than argued at length; its interest now lies in the fact that it made '''dated, checkable predictions''' about five specific experimental programmes, two of which have since been settled.

==The five verdicts==

===1. Spotting distant signs of life===

Li holds that the search for extraterrestrial life "is more difficult than to find a needle in a haystack, the probability of zero probability events", and cannot be confirmed "in many many years."

===2. Seeing through the molecular mirror===

The goal is to detect the tiny energy difference between left- and right-handed chiral molecules caused by the weak interaction. Li quotes the article's own figure — the best instruments can then discern differences of about '''5 parts in 10¹⁴''', roughly a million times better than an off-the-shelf spectrometer — and judges that improving resolution by a further factor of a million is impossible in the near term.

===3. Looking for extra dimensions===

"Physical space is originally three-dimensional. Multidimensional (more than 3-D) space theory has always been fallacy. Experimental measurement is impossible."

===4. Catching a gravity wave===

"Gravity is the equivalent expression of the momentum. Graviton does not exist. Interaction between objects has always existed, there is no gravitational waves. To catch a gravity wave is impossible." This follows from Li's own account of gravitation as momentum exchange with microparticles, set out in his other papers.

===5. Redefining the kilogram===

Li raises two objections to defining the kilogram via '''Planck's constant''' in the way the metre is defined via the [[Speed of Light|speed of light]]. First, he holds it is not settled whether the speed of light in vacuum is an absolute constant or a range. Second, and more practically, that "the vast majority of people still cannot characterize the distance traveled by light… in precisely 1/299,792,458 seconds", so the definition has little practical value — whereas the physical prototype in Paris, though it varies minutely with environment and time, "is easy to use." He adds that a definition routed through ''E'' = ''mc''², which he holds to be wrong, must inherit that error.

==Assessment==

Because this commentary attached the word "impossible" to five dated, specific programmes, it can now be marked. The record is mixed, and two of the verdicts have been decisively overturned.

'''Item 4 was refuted within four years.''' [[Gravitational Waves|Gravitational waves]] were detected by LIGO on 14 September 2015 and announced in February 2016 — the signal GW150914, from a binary black-hole merger, seen simultaneously at two independent detectors with a waveform matching the predicted inspiral–merger–ringdown. The 2017 Nobel Prize in Physics followed, and detections are now routine, including GW170817, whose gravitational and gamma-ray signals arrived within about 1.7 seconds of each other after travelling some 130 million light years. This is not a matter of interpretation: the flat statement "there is no gravitational waves… to catch a gravity wave is impossible" is false.

'''Item 5 was accomplished within seven years.''' The kilogram was redefined in terms of the '''Planck constant''', with the new SI taking effect on 20 May 2019. The Kibble balance and the silicon-sphere (Avogadro) route agreed well enough to fix ''h'' = 6.62607015 × 10⁻³⁴ J·s exactly. Li's practical objection — that ordinary users cannot realise such a definition — misunderstands what a definition is for: metrological definitions are realised by national standards laboratories and disseminated through calibration, and the prototype's drift he waves away as "extremely tiny" was precisely the problem, since a unit that changes cannot anchor a measurement system.

'''Items 1 and 3 have not been achieved''', which is as far as it goes. No confirmed biosignature has been detected, though the field has advanced considerably with transit spectroscopy and JWST; and no extra dimensions have been found, with collider and short-range gravity experiments continuing to tighten the bounds. Li is right about the outcomes so far, but his reasoning is assertion rather than argument — "multidimensional space theory has always been fallacy" is a statement of position, and the honest reason no extra dimensions have been seen is that the searches have returned null results, not that the searches were incoherent.

'''Item 2 remains open and Li's estimate was reasonable.''' The parity-violating energy difference between enantiomers has still not been measured, and the required sensitivity remains out of reach. This is the one verdict where his judgement of experimental difficulty, based on the article's own quoted figures, has held up well.

The broader lesson is one this wiki's readers may find useful in both directions. Predicting that a hard experiment will fail is cheap, and the two items Li called '''impossible on theoretical grounds''' — rather than on grounds of engineering difficulty — are exactly the two that were accomplished. His purely practical judgements, by contrast, have so far proved sound. That is a distinction worth carrying into any assessment of what mainstream physics can and cannot do.

==See also==

* [[Zifeng Li]]
* [[Gravitational Waves]], [[Speed of Light]]
* [[Standard Model]]
* [[:Category:Relativity]]

[[Category:Scientific Paper|Comments on Frontier experiments]]
[[Category:Gravity|Comments on Frontier experiments]]
[[Category:Relativity|Comments on Frontier experiments]]
[[Category:Astronomy|Comments on Frontier experiments]]