Science stories of the week

[exchemist]

More on this subject that you might find interesting.

Venus had Earth-like plate tectonics billions of years ago, study suggests

Simulations produced by a Brown-led research team offer evidence that Venus once had plate tectonics — a finding that opens the door for the possibility of early life on the planet and insights into its history.

www.brown.edu

Thanks, and yes it is interesting, though it throws up more questions in my mind than answers.

The article seems to assert a connnection between Venus's dense and hot atmosphere and the lack of plate tectonics. It reads for the most part as if the former (atmospheric composition) is a consequence of the latter. However it also seems to suggest the reverse, that the atmosphere affects the presence or absence of plate tectonics. But either way, there is no explanation of the linkages.

Racking my brains about this, I think I have read that water plays a surprisingly big role in plate tectonics on Earth. Subducted water from the oceans produces a wide range of hydrated minerals, many of which are mechanically weaker than their anhydrous relatives. This helps the asthenosphere (mantle) to deform plastically over time, which is what is needed to have the convective cells that drive plate tectonics at the surface. Water also is driven off where temperatures are high and pressures relatively low, which is part of what generates volcanism above descending subducted slabs - a form of vulcanism absent on Venus, apparently. [Sorry, volcanism - my age is showing]

I'm wondering if what your linked article is taking as read is some argument that, if the surface of Venus is too hot for water molecules to have been retained in its atmosphere, there may no longer be enough water to keep the mantle supple enough to support convection. Or something like that. But I am only speculating.

 

[exchemist]

I think Webb deserves a mention. Confirmation of a galaxy that formed only 280 million years after the BB.

What is remarkable about that, apart from the distance involved?

 

[Pinball1970]

What is remarkable about that, apart from the distance involved?

What was remarkable about Bob Beamon's jump besides the distance? (Wink)

These very early galaxies are massive and well developed considering the short cosmic time they have had to develop.
Hubble had hints of some but none as early as this and the indication is 280 million years does not have to be the limit for Webb.

There is detailed paper regarding the first Billion years according to JWST, it is re-writing the rule book. I will post it.

 

[Pinball1970]

Webb re-writing the rule book https://arxiv.org/abs/2405.21054

They are less than two years in

"From the abstract The scientific community is analyzing a wealth of JWST imaging and spectroscopic data from that era, and is in the process of rewriting the astronomy textbooks. Here, 1.5 years into the JWST science mission, we provide a snapshot of the great progress made towards understanding the initial chapters of our cosmic history. "

 

[Pinball1970]

For this week, this popped up in my feed. The title confused as I have never heard of this.

Researcher suggests that gravity can exist without mass, mitigating the need for hypothetical dark matter

Dark matter is a hypothetical form of matter that is implied by gravitational effects that can't be explained by general relativity unless more matter is present in the universe than can be seen. It remains virtually as mysterious as it was nearly a century ago when first suggested by Dutch...

phys.org

EDIT: Yes this is well above my pay grade, Einstein field equations, tensors etc..... Anyway the full paper is open access so be good to hear a view from James or one of the other guys.

 

[exchemist]

What was remarkable about Bob Beamon's jump besides the distance? (Wink)

These very early galaxies are massive and well developed considering the short cosmic time they have had to develop.
Hubble had hints of some but none as early as this and the indication is 280 million years does not have to be the limit for Webb.

There is detailed paper regarding the first Billion years according to JWST, it is re-writing the rule book. I will post it.

OK, but this paper is really just making the general point that, being an IR telescope, the JWST is able to detect objects with larger red-shifts (into the IR), so much farther away and therefore, bearing in mind the time light takes get to us from so far away, from far earlier epochs than was previously possible. I see there are already some surprises, to do with galaxies looking more mature than had been expected, more oxygen and other "metals" present, and so forth.

 

[Pinball1970]

OK, but this paper is really just making the general point that, being an IR telescope, the JWST is able to detect objects with larger red-shifts (into the IR), so much farther away and therefore, bearing in mind the time light takes get to us from so far away, from far earlier epochs than was previously possible. I see there are already some surprises, to do with galaxies looking more mature than had been expected, more oxygen and other "metals" present, and so forth.

IR is not knew and granted tech improves year and year but come on!
This is a paradigm shift.
Look at the previous images from IRAS or Spitza.
Also as you have pointed out it is not all about pretty pictures, they are getting the most accurate spectral data giving the most precise red shift and composition data ever.

Obviously being a chemist you are hard to please but let's see how you view:

First Population 3 star signature.
First galaxy discovery that indicates formation only 200 million years after the BB.
First atmospheric signature for life on an exoplanet.

Time line? Check in this time next year?

 

[exchemist]

IR is not knew and granted tech improves year and year but come on!
This is a paradigm shift.
Look at the previous images from IRAS or Spitza.
Also as you have pointed out it is not all about pretty pictures, they are getting the most accurate spectral data giving the most precise red shift and composition data ever.

Obviously being a chemist you are hard to please but let's see how you view:

First Population 3 star signature.
First galaxy discovery that indicates formation only 200 million years after the BB.
First atmospheric signature for life on an exoplanet.

Time line? Check in this time next year?

Signature for life? Now that would be something. What have they found?

 

[C C]

For this week, this popped up in my feed. The title confused as I have never heard of this.

Researcher suggests that gravity can exist without mass, mitigating the need for hypothetical dark matter

Dark matter is a hypothetical form of matter that is implied by gravitational effects that can't be explained by general relativity unless more matter is present in the universe than can be seen. It remains virtually as mysterious as it was nearly a century ago when first suggested by Dutch...

phys.org

[...]

Richard Lieu: "This initiative is in turn 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."​

But similar to identifying the precise candidate(s) for dark matter, topological defects like cosmic strings (etc) -- lack any solid confirmation so far. It seems akin to trading one "invisible or elusive" with another "invisible or elusive".

Instead of the one-dimensional strands of trapped false vacuum, he's apparently adding an extra dimension to produce spherical arrangements of such. Replacing spacetime curvature (caused by mass) with these topological defect geometries -- yet still classifying the supposed deflecting effects on stars and so-forth as gravitational???

A cosmic string would have mass, but his concentric shell version cancels that out. The complexity of it sounds artificial without a natural explanation provided that would commonly bring those structures about in the early universe. Alluding in general to a "symmetry-breaking cosmological phase transition" doesn't offer a precise origin, which he admits this paper doesn't deal with.

"The shells in my paper consist of a thin inner layer of positive mass and a thin outer layer of negative mass; the total mass of both layers—which is all one could measure, mass-wise—is exactly zero, but when a star lies on this shell it experiences a large gravitational force pulling it towards the center of the shell. [...] This paper does not attempt to tackle the problem of structure formation. [...] But it is the first [mathematical] proof that gravity can exist without mass."​

- - - - - - - - - - - - - - - - - - - - - -

Topological defects in cosmology

https://ned.ipac.caltech.edu/level5/March02/Gangui/paper.pdf

Cosmic strings and other topological defects

https://core.ac.uk/download/pdf/25177637.pdf

Gravitation: From the general theory of relativity such a geometrical defect must be in tension, and would be manifested by mass. Even though cosmic strings are thought to be extremely thin, they would have immense density, and so would represent significant gravitational wave sources. A cosmic string about a kilometer in length may be more massive than the Earth.

[...] During the expansion of the universe, cosmic strings would form a network of loops, and in the past it was thought that their gravity could have been responsible for the original clumping of matter into galactic superclusters. It is now calculated that their contribution to the structure formation in the universe is less than 10%.

 

[Pinball1970]

Signature for life? Now that would be something. What have they found?

Nothing yet to my knowledge. Significant anyway.

 

[exchemist]

Nothing yet to my knowledge. Significant anyway.

Oh I see: you are not referring to discoveries but to things that JWST might possibly discover.

 

[wegs]

Thanks, and yes it is interesting, though it throws up more questions in my mind than answers.

The article seems to assert a connnection between Venus's dense and hot atmosphere and the lack of plate tectonics. It reads for the most part as if the former (atmospheric composition) is a consequence of the latter. However it also seems to suggest the reverse, that the atmosphere affects the presence or absence of plate tectonics. But either way, there is no explanation of the linkages.

Racking my brains about this, I think I have read that water plays a surprisingly big role in plate tectonics on Earth. Subducted water from the oceans produces a wide range of hydrated minerals, many of which are mechanically weaker than their anhydrous relatives. This helps the asthenosphere (mantle) to deform plastically over time, which is what is needed to have the convective cells that drive plate tectonics at the surface. Water also is driven off where temperatures are high and pressures relatively low, which is part of what generates volcanism above descending subducted slabs - a form of vulcanism absent on Venus, apparently. [Sorry, volcanism - my age is showing]

I'm wondering if what your linked article is taking as read is some argument that, if the surface of Venus is too hot for water molecules to have been retained in its atmosphere, there may no longer be enough water to keep the mantle supple enough to support convection. Or something like that. But I am only speculating.

I've read that (lack of) water in addition to other factors (periodic ''resurfacing'' events, extremely high temps, etc), is partially responsible for the lack of plate tectonics on Venus, currently.

I can't help but wonder if Earth will ever end up like this, millions of years from now. I tend to ''compare'' Earth and Venus in terms of climate change, and could Earth ever reach such extreme conditions?

 

[exchemist]

I've read that (lack of) water in addition to other factors (periodic ''resurfacing'' events, extremely high temps, etc), is partially responsible for the lack of plate tectonics on Venus, currently.

I can't help but wonder if Earth will ever end up like this, millions of years from now. I tend to ''compare'' Earth and Venus in terms of climate change, and could Earth ever reach such extreme conditions?

Can you recall where you read about this role of water and absence of plate tectonics on Venus? I'd be interested in reading a bit more about that.

Regarding loss of light molecules from the atmosphere, there is a Botlzmann distribution (a sort of bell curve) of molecular velocities in a gas, the shape of which depends on the temperature (thermal kinetic energy being proportional to temperature, as mentioned in another recent thread). Lower mass molecules have a higher mean speed, at any given temperature, than heavier ones. f the high velocity "tail" of this distribution curve lies above the graviatational escape velocity for the planet, then those molecules will be continually being lost into space, eventually depleting the atmosphere of that type of molecule. There can also be high altitude photolysis processes, by which molecules get broken up by sunlight into smaller (lighter) pieces, which then have higher thermal velocities for a given temperature and are lost more rapidly. Venus, being closer to the sun than Earth, may experience more photolysis in the upper atmosphere than Earth, I imagine.

 

[wegs]

Can you recall where you read about this role of water and absence of plate tectonics on Venus? I'd be interested in reading a bit more about that.

Here are a couple of articles and an abstract, but I’ll have to retrace my virtual steps as I can't recall some of the other sources where I've read that lack of water might relate to lack of tectonic plates.

https://www.nytimes.com/2021/06/22/science/venus-tectonic-activity.html
From the article - Long ago, Venus had an ocean’s worth of water, for potentially billions of years. This could have made plate tectonics possible, as liquid water permits plates to break, bend and flow. This process also regulates the climate by burying and erupting carbon, preventing worlds from undergoing runaway global warming that would render them uninhabitable.

This article goes a little off the beaten path, but you might find it insightful.

How 'Earth's twin' Venus lost its water and became a hellish planet

"Venus has 100,000 times less water than the Earth, even though it's basically the same size and mass."

www.space.com

Venus water loss is dominated by HCO+ dissociative recombination - Nature

Water loss to space late in Venus history is shown to be more active than previously thought, with unmeasured HCO+ dissociative recombination dominating present-day H loss.

www.nature.com

 

[exchemist]

Here are a couple of articles and an abstract, but I’ll have to retrace my virtual steps as I can't recall some of the other sources where I've read that lack of water might relate to lack of tectonic plates.

https://www.nytimes.com/2021/06/22/science/venus-tectonic-activity.html
From the article - Long ago, Venus had an ocean’s worth of water, for potentially billions of years. This could have made plate tectonics possible, as liquid water permits plates to break, bend and flow. This process also regulates the climate by burying and erupting carbon, preventing worlds from undergoing runaway global warming that would render them uninhabitable.

This article goes a little off the beaten path, but you might find it insightful.

How 'Earth's twin' Venus lost its water and became a hellish planet

"Venus has 100,000 times less water than the Earth, even though it's basically the same size and mass."

www.space.com

Venus water loss is dominated by HCO+ dissociative recombination - Nature

Water loss to space late in Venus history is shown to be more active than previously thought, with unmeasured HCO+ dissociative recombination dominating present-day H loss.

www.nature.com

I'm afraid the NYT article is behind a paywall but I've looked at the other two, which confirm that Venus is thought to have lost its water to space. I was not aware of the role of HCO+, though, in scavenging the last traces.

Sadly it's the NYT one that directly addresses the role of water in enabling plate tectonnics. However I can see from the segment you quote that it more or less confirms my recollection regarding water and plate tectonics on Earth.

So there we have it: the escape of water from Venus is why it doesn't have plate tectonics today, though it may have done in the past when water was still present.

 

[wegs]

I'm afraid the NYT article is behind a paywall but I've looked at the other two, which confirm that Venus is thought to have lost its water to space. I was not aware of the role of HCO+, though, in scavenging the last traces.

Sadly it's the NYT one that directly addresses the role of water in enabling plate tectonnics. However I can see from the segment you quote that it more or less confirms my recollection regarding water and plate tectonics on Earth.

So there we have it: the escape of water from Venus is why it doesn't have plate tectonics today, though it may have done in the past when water was still present.

Copied and pasted for you. Strange - the article isn't hidden behind a paywall for me, and I'm not a paid subscriber to the NYT.

Venus Lacks Plate Tectonics. But It Has Something Much More Quirky.​

Scientists say giant slices of rock may move across the surface of Earth’s closest neighbor like pack ice floating in the sea.
By Robin George Andrews
June 22, 2021

Within the next decade or so, Venus will be visited by a fleet of spacecraft. This grand tour of the second planet, the likes of which hasn’t been seen since the Cold War, is being driven by the quest to solve a profound planetary puzzle. Earth and Venus are the same size, are right next to each other and are made of the same star stuff. But Earth became an oasis while Venus became an acid-flecked inferno. Why?

To derive an answer, every aspect of Venus requires examination. That includes the way its face has metamorphosed over time. Earth has plate tectonics, the gradual migration of continent-size geologic jigsaw pieces on its surface — a game-changing sculptor that crafts an exuberance of diverse volcanoes, giant mountain ranges and vast ocean basins.

Venus doesn’t have plate tectonics. But according to a study published Monday in the Proceedings of the National Academy of Sciences, it may possess a quirky variation of that process: Parts of its surface seem to be made up of blocks that have shifted and twisted about, contorting their surroundings as they went.

These boogying blocks, thin and flat slices of rock referred to as campi (Latin for “fields”), can be as small as Ireland or as expansive as Alaska. They were found using data from NASA’s Magellan orbiter mission, the agency’s last foray to Venus. In the early 1990s, it used radar to peer through the planet’s obfuscating atmosphere and map the entire surface. Taking another look at these maps, scientists found 58 campi scattered throughout the planet’s lava-covered lowlands.

A radar view of Nüwa Campus, the largest block in the Venus lowlands, which is bounded by tectonic structures.Credit...Paul K. Byrne and Sean C. Solomon

These campi are bordered by lines of small mountain ranges and grooves, features that have also been warped and scarred over time. What made them? According to Paul Byrne, a planetary scientist at North Carolina State University and the study’s lead author, there is only one reasonable explanation: Essentially dragged around by the flowing mantle below, the campi “have been shimmying around the place, just like pack ice.” Campi moving toward immobile land would cause the ground to crumple up, forming mountains. One moving away would have stretched the land, opening grooves. And along these boundaries, campi moving side-to-side would have left strain marks and etchings.

That this deformation took place in the lowlands of Venus is significant: The lava smothering them is anywhere between 750 and 150 million years old, making these landscapes some of the planet’s youngest. That means the tectonic two-step of these campi happened relatively recently in the solar system’s history. But is this dance still happening today?

NASA’s VERITAS and Europe’s EnVision missions will find out. Equipped with their own advanced radar systems, these orbiters will examine these campi in high-resolution, allowing scientists to ascertain if any have shimmied about since the days of Magellan. If they have, then it will further evidence a long-harbored notion: Venus is tectonically active, if not as hyperactive or as dynamic as Earth.

Long ago, Venus had an ocean’s worth of water, for potentially billions of years. This could have made plate tectonics possible, as liquid water permits plates to break, bend and flow. This process also regulates the climate by burying and erupting carbon, preventing worlds from undergoing runaway global warming that would render them uninhabitable.

But one of several possible apocalypses — perhaps multiple volcanic cataclysms — turned Venus into an arid hellscape, and its plate tectonics would have shut down. Consequently, for the past billion years or so, the entire planet’s surface was a solitary, stagnant and largely static plate.

But that doesn’t mean the planet has become quaver-free. Thanks to missions like Magellan, scientists have previously spotted fault networks, rift zones and mountain ridges — the scar tissue left by both ancient and somewhat more contemporary movement. If this new study is correct, and entire swaths of Venus have been recently jiggling about, then the planet’s surface “is more mobile than people have conventionally assumed,” said Joseph O’Rourke, a planetary scientist at Arizona State University who wasn’t involved with the work.

Explaining why Venus has this surprising tectonic tempo would have hefty implications. There are countless Earth- and Venus-size worlds in the cosmos, and their tectonic activity will also determine their fates. But “we can’t claim to understand any rocky world in the solar system or beyond if we can’t understand Earth and its nearest neighbor,” Dr. O’Rourke said.

Venus, and its myriad surprises, certainly isn’t making that task easy.

 

[exchemist]

Copied and pasted for you. Strange - the article isn't hidden behind a paywall for me, and I'm not a paid subscriber to the NYT.

Venus Lacks Plate Tectonics. But It Has Something Much More Quirky.​

Scientists say giant slices of rock may move across the surface of Earth’s closest neighbor like pack ice floating in the sea.
By Robin George Andrews
June 22, 2021

Within the next decade or so, Venus will be visited by a fleet of spacecraft. This grand tour of the second planet, the likes of which hasn’t been seen since the Cold War, is being driven by the quest to solve a profound planetary puzzle. Earth and Venus are the same size, are right next to each other and are made of the same star stuff. But Earth became an oasis while Venus became an acid-flecked inferno. Why?

To derive an answer, every aspect of Venus requires examination. That includes the way its face has metamorphosed over time. Earth has plate tectonics, the gradual migration of continent-size geologic jigsaw pieces on its surface — a game-changing sculptor that crafts an exuberance of diverse volcanoes, giant mountain ranges and vast ocean basins.

Venus doesn’t have plate tectonics. But according to a study published Monday in the Proceedings of the National Academy of Sciences, it may possess a quirky variation of that process: Parts of its surface seem to be made up of blocks that have shifted and twisted about, contorting their surroundings as they went.

These boogying blocks, thin and flat slices of rock referred to as campi (Latin for “fields”), can be as small as Ireland or as expansive as Alaska. They were found using data from NASA’s Magellan orbiter mission, the agency’s last foray to Venus. In the early 1990s, it used radar to peer through the planet’s obfuscating atmosphere and map the entire surface. Taking another look at these maps, scientists found 58 campi scattered throughout the planet’s lava-covered lowlands.

A radar view of Nüwa Campus, the largest block in the Venus lowlands, which is bounded by tectonic structures.Credit...Paul K. Byrne and Sean C. Solomon

These campi are bordered by lines of small mountain ranges and grooves, features that have also been warped and scarred over time. What made them? According to Paul Byrne, a planetary scientist at North Carolina State University and the study’s lead author, there is only one reasonable explanation: Essentially dragged around by the flowing mantle below, the campi “have been shimmying around the place, just like pack ice.” Campi moving toward immobile land would cause the ground to crumple up, forming mountains. One moving away would have stretched the land, opening grooves. And along these boundaries, campi moving side-to-side would have left strain marks and etchings.

That this deformation took place in the lowlands of Venus is significant: The lava smothering them is anywhere between 750 and 150 million years old, making these landscapes some of the planet’s youngest. That means the tectonic two-step of these campi happened relatively recently in the solar system’s history. But is this dance still happening today?

NASA’s VERITAS and Europe’s EnVision missions will find out. Equipped with their own advanced radar systems, these orbiters will examine these campi in high-resolution, allowing scientists to ascertain if any have shimmied about since the days of Magellan. If they have, then it will further evidence a long-harbored notion: Venus is tectonically active, if not as hyperactive or as dynamic as Earth.

Long ago, Venus had an ocean’s worth of water, for potentially billions of years. This could have made plate tectonics possible, as liquid water permits plates to break, bend and flow. This process also regulates the climate by burying and erupting carbon, preventing worlds from undergoing runaway global warming that would render them uninhabitable.

But one of several possible apocalypses — perhaps multiple volcanic cataclysms — turned Venus into an arid hellscape, and its plate tectonics would have shut down. Consequently, for the past billion years or so, the entire planet’s surface was a solitary, stagnant and largely static plate.

But that doesn’t mean the planet has become quaver-free. Thanks to missions like Magellan, scientists have previously spotted fault networks, rift zones and mountain ridges — the scar tissue left by both ancient and somewhat more contemporary movement. If this new study is correct, and entire swaths of Venus have been recently jiggling about, then the planet’s surface “is more mobile than people have conventionally assumed,” said Joseph O’Rourke, a planetary scientist at Arizona State University who wasn’t involved with the work.

Explaining why Venus has this surprising tectonic tempo would have hefty implications. There are countless Earth- and Venus-size worlds in the cosmos, and their tectonic activity will also determine their fates. But “we can’t claim to understand any rocky world in the solar system or beyond if we can’t understand Earth and its nearest neighbor,” Dr. O’Rourke said.

Venus, and its myriad surprises, certainly isn’t making that task easy.

OK that actually doesn’t seem to add a lot to the segment you posted before. And the writer seems unaware of the mechanism by which Venus probably lost its water, referring only to some speculative “apocalypses”. So we are one up on the writer here, I think

 

[wegs]

OK that actually doesn’t seem to add a lot to the segment you posted before. And the writer seems unaware of the mechanism by which Venus probably lost its water, referring only to some speculative “apocalypses”. So we are one up on the writer here, I think

Agreed!

 

[Pinball1970]

Oh I see: you are not referring to discoveries but to things that JWST might possibly discover.

Yes things to come. Not really a prediction as those three points were part of the science mission before it launched.
It has already achieved the most distant galaxy and has plenty of time to improve on that.
The other two are far more difficult for different reasons.

 

[Pinball1970]

on that note....this time spiral galaxy formation.

Scientists spot more Milky Way-like galaxies in early universe, advancing our understanding of how galaxies were formed

University of Missouri scientists are peering into the past and uncovering new clues about the early universe. Since light takes a long time to travel through space, they are now able to see how galaxies looked billions of years ago.

phys.org