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The story
A detector called LUX-ZEPLIN (LZ), installed 1.6km underground in South Dakota, USA, has published a paper reporting a single observed event believed to be a nuclear recoil caused by a dark matter candidate particle. In the thread, some pointed out that the energy scale is close to that of the gamma-ray observations previously announced by Professor Toya and colleagues, suggesting both findings could bolster the leading “WIMP” hypothesis. Meanwhile, basic questions about what dark matter actually is, and how to interpret the claim that it makes up 85% of the universe’s mass, also sparked discussion — producing a wide range of replies from expert-level analysis to simple curiosity.
A dark matter detector installed 1.6km underground reportedly detected “one strange particle”
Dark matter is a hypothetical substance believed to make up about 25% of the universe’s matter-energy and about 85% of its mass.
The dark matter detector “LUX-ZEPLIN (LZ),” built to observe such dark matter, has reportedly detected one strange particle.
Source: lz.lbl.gov / Original article here
What people said
Professor Toya's work assumed dark matter annihilation at roughly 500 times the mass of a proton,
while this LZ experiment points to nuclear recoil caused by dark matter over 200 times the proton's mass.
It's interesting that the energy scales are roughly in the same ballpark.
If dark matter's identity as a WIMP ever gets confirmed, that'd be a once-in-several-decades physics discovery.
In that case, maybe the Nobel Prize would go to Professor Toya and someone from the LZ team?
There's interference happening, so there's no doubt it exists as actual matter!
Maybe the outside of our universe is filled with dark matter.
Wouldn't that mean the expansion speed is confirmed to exceed the speed of light?
Since there would be atoms outside the universe that existed before the Big Bang happened, if we could investigate outside the universe, couldn't we prove that matter existed (before the Big Bang)?
Light has no mass, so shouldn't it get reflected by dark matter? Why doesn't light get reflected?
No matter how light something is, if the surrounding matter is heavier than its 'zero mass,' its motion should still be governed by the energy laws matching the surrounding physical energy.
If energy is being transmitted from all directions by the surrounding matter, then depending on how each atom's energy is transmitted and how much energy the atoms interacting with dark matter carry, you'd expect dark matter's collective behavior to show up looking strange in observations.
(*Dark matter's movement is said to be random and unpredictable)
Does the quantum mechanics phenomenon of the same thing existing in two places at once mean dark matter is what's present there?
"Yeah…"
Hope the mysteries of dark matter get solved while I'm still alive.
What's the matter?
Another round of dark excuses, huh?
>> Dark matter is a hypothetical substance believed to make up about 25% of the universe's matter-energy and about 85% of its mass. The dark matter detector "LUX-ZEPLIN (LZ)," built to observe such dark matter, has reportedly detected one strange particle.
About 25% of matter-energy = that means dark energy, right?
About 85% of mass = that means 85% of the universe's total area is dark matter, right?
If persistently 85% of the universe is dark matter, does that mean dark matter is what's carrying gravitational waves through the universe?
Every bit of matter on Earth becomes effectively massless once it leaves for space, but under certain conditions it can trigger a phenomenon that generates dark energy.
Since matter on Earth becomes effectively massless, you could also say its mass arises from interference with dark matter.
How should we even think about this?
85% of the solar system's space is supposedly dark matter!
We launch satellites, so those satellites must be coming into contact with dark matter — so why insist it's undetectable when contact is clearly happening?
"couldn't we prove that substance (typo) existed"
↓
should read: "couldn't we prove that matter existed before the Big Bang"
Do stellar-stream distortions prove dark matter? An astronomy assumption gets overturned
About 15,000 simulations show a galaxy's own gravity alone — with no dark matter clump needed — can produce disturbances in a star stream. This calls for a rethink of conventional dark matter searches that rely solely on optical shape.
https://xenospectrum.com/stellar-streams-dark-matter-simulation-complexity-floor/
Couldn't even old-fashioned telescopes pin down the distribution of dark matter in detail?
With the Roman Space Telescope, will we finally be able to fully decode the energy transfer within streams in the solar system?
If a stream is present, that marks a main channel of energy transfer in the universe.
After all, 85% of the universe's mass is dark matter!
If dark matter passes through a "25%-water-clump" spot, wouldn't that spot — now sphere-shaped — get swept up as if a dark matter "bullet" were passing through the mass inside it, causing that 25% object to move in a swirling pattern?
85% of the universe's mass is dark matter.
Mass = heavy, right?
Heavy matter from Earth becomes lighter once it's out in space.
So dark matter that gets inside the Earth must be lighter than matter on Earth's surface, right?
Since the Earth is also rotating, wouldn't dark matter get flung back out into space before it can get inside the Earth?
And given that, wouldn't that be why winds blow up in the upper atmosphere and so on?
It's strange that something with mass (≈ interacting gravitationally) doesn't clump together in one place.
Even if it doesn't fully clump, you'd expect it to concentrate toward the galactic center.
Is it that the nature of gravity between dark matter particles ≠ the nature of gravity between dark matter and ordinary matter?
Or is it that
gravity between dark matter particles is balanced out by gravity (and other forces) between dark matter and ordinary matter?
The moment the universe stops expanding, it happens right away!
If the dark energy driving the expansion is infinite, or keeps growing, then that day never comes.
Background and key points of this topic
The LZ experiment places a liquid-xenon detector deep underground in South Dakota, USA, shielding it from cosmic-ray noise to catch faint signals — what’s being reported here isn’t a “discovery” but a single statistical candidate event. The WIMP (Weakly Interacting Massive Particle), the leading dark matter candidate, is thought to have roughly a hundred times the mass of a proton, and the thread noted how close that is to the annihilation mass scale suggested by Professor Toya’s gamma-ray observations. At the same time, some replies confused the “85% of the universe’s mass” figure with a spatial or area-based percentage. That figure is actually a statistical ratio within the universe’s overall energy-mass budget — it doesn’t mean 85% of local space is literally filled with dark matter, a distinction that’s easy to misread.
※This article is compiled and summarized from the 5ch (Science News+) thread “A dark matter detector installed 1.6km underground reportedly detected ‘one strange particle’.”
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