science

time for big bang revision

Lemmyversers, I'm looking for some help developing a new mnemonic device.

Inspired by a video by Epic Spaceman, where he explains a handy system for comparing the size of things from a banana to an atom, I’ve come up with a mnemonic device to aid in remembering these scales.

He lists items, each smaller than the previous by a factor of 10:

It goes:

• Banana
• Coin
• Edge of the coin
• Waterbear/microorganism
• Red blood cell
• Bacteria
• "Good virus"/Bacteriophage
• Corona Virus/"Bad Virus"
• DNA
• Atom

So a coin is roughly 1/10 a banana, and the edge of that coin is roughly 1/10 the size if that coin.

It gives good references for thinking about other things if similar size. A sort of banana for scale at each factor of 10.

And allows you to quickly determine approximations like Covid is roughly 1000 times smaller than a red blood cell. Or an atom is roughly 1 billion times smaller than a banana. (That doesn't sound right. Is that actually right?)

Do you think that's a useful memory tool? And are these best touchstones for scale at each level?

The mnemonic I've come up with for it as you may have guessed, is:

• Be
• Cool
• Even
• When
• Really
• Big
• Goblins
• Casually
• Drop
• Acid

Do you have any better ideas or tweaks you"d recommend for the mnemonic or the touchstones?

Would this be helpful when trying to wrap your head around the scale of the micro?

Also, what would make for a good macro version of this? Where everything got bigger by a factor of 10?

nice color pics from far-side, Chang’e-6

Even as a flying squid, I'm repulsed.

humans must be optimized for hand tools and short life spans.

clickbait headline but interesting materials research. 'a unique magnetic transition phenomenon known as the "spin-fluctuating devil's staircase."'

Tl;dr an undergraduate paper last year claiming females hunt just as often as males got picked up by the media and amplified before it was discovered their analysis was deeply flawed and unreliable. Here several anthropologists present a very gracious rebuttal.

High-temperature fusion plasma experiments conducted in the Large Helical Device (LHD) of the National Institute for Fusion Science (NIFS), have renewed the world record for an acquired data amount, 0.92 terabytes (TB) per experiment, in February 2022, by using a full range of state-of-the-art plasma diagnostic devices.

The International Thermonuclear Experimental Reactor (ITER), which is currently under construction in France through the international collaboration of seven parties, is expected to generate approximately 1 TB of data per experiment in 10 years, and LHD is currently the only experiment in the world that produces data closely aligned to ITER.

The promotion of "Open Science," in which large-scale research data assets are utilized and shared across society, was adopted as a joint statement at the G7 meeting held in Sendai, Japan in 2023. NIFS started full-fledged efforts toward Open Science by establishing the "Open Access Policy" in February 2022 and the "Research Data Policy" in October 2022.

Since 2023, all the data obtained from LHD experiments are open to the public immediately after acquisition and analysis is completed. All computing program source codes for data analysis are also openly available.

. . .

Chose a title that reflects what the article actually discusses!

A new study by astrophysicist Richard Lieu suggests that gravity can exist without mass, proposing thin, shell-like layers of 'topological defects' as an alternative to dark matter for explaining the gravitational binding of galaxies. This theory posits that these defects create a gravitational force without detectable mass, potentially eliminating the need for dark matter in current cosmological models

Lieu started out trying to find another solution to the Einstein field equations, which relate the curvature of space-time to the presence of matter within it. As Einstein described in his 1915 theory of general relativity, space-time warps around bundles of matter and streams of radiation in the Universe, depending on their energy and momentum. That energy is, of course, related to mass in Einstein's famous equation: E=mc2. So an object's mass is linked to its energy, which bends space-time -- and this curvature of space-time is what Einstein described as gravity, a notch more sophisticated than Newton's 17th-century approximation of gravity as a force between two objects with mass. In other words, gravity seems inextricably linked to mass. Not so, posits Lieu.

In his workings, Lieu set about solving a simplified version of the Einstein field equations that allows for a finite gravitation force in the absence of any detectable mass. He says his efforts were "driven by my frustration with the status quo, namely the notion of dark matter's existence despite the lack of any direct evidence for a whole century." Lieu's solution consists of shell-shaped topological defects that might occur in very compact regions of space with a very high density of matter. These sets of concentric shells contain a thin layer of positive mass tucked inside an outer layer of negative mass. The two masses cancel each other out, so the total mass of the two layers is exactly zero. But when a star lies on this shell, it experiences a large gravitational force dragging it towards the center of the shell. "The contention of my paper is that at least the shells it posits are massless," Lieu says. If those contentious suggestions bear any weight, "there is then no need to perpetuate this seemingly endless search for dark matter," Lieu adds.

The next question, then, is how to possibly confirm or refute the shells Lieu has proposed through observations. "The increasing frequency of sightings of ring and shell-like formation of galaxies in the Universe lends evidence to the type of source being proposed here," Lieu writes in his paper. Although he admits that his proposed solution is "highly suggestive" and cannot alone discredit the dark matter hypothesis. "It could be an interesting mathematical exercise at best," Lieu concludes. "But it is the first [mathematical] proof that gravity can exist without mass."

The study has been published in Monthly Notices of the Royal Astronomical Society.