WEBVTT
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This is Spacetime Series twenty eight, episode one hundred and
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twenty for broadcast on the sixth of October twenty twenty five.
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Coming up on Space Time and You study warns the
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universe will end in twenty billion years from now and
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you three dimensional map of our Milky Way galaxy and
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how fung guys set the stage for life on land
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on planet Earth.
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All that and more Coming up on space Time.
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Welcome to Space Time with Stuart gary.
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Any study claims the universe is now approaching the midpoint
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of its thirty three billion year lifespan and will come
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to an end in around twenty billion years time. A
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report in the Journal of Cosmology and Astroparticle Physics says
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calculations based on new data from dark energy observatories suggests
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that after expanding to its peak size and about eleven
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billion years from now, our universe will begin to contract,
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eventually snapping back like a rubber band to form a
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singularity at the end of time. The study's lead author,
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Henry Tie from Cornell University, says he reached his conclusion
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after adding new data to a model involving Albert Einstein's
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famous cosmological constant, A factor introduced more than a century
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ago by Einstein and still used by cosmologists today to
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predict the future of the universe. Tie says that for
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the last twenty years, scientists to believe the cosmological consonant
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was positive and the universe would therefore expand forever. But
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he claims the new data seems to indicate that in fact,
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the cosmological constant is actually negative and the universe will
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end up in a big crunch. Right now, the universe
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is thirteen point eight billion years old, and it's still
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expanding now. According to current models based on dark energy.
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It's two simplest fates of that either continuous present expansion forever,
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that's if the cosmological constant is positive, or alternatively, if
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the cosmological constant is actually negative, it will reach a
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maximum size before contracting, eventually it collapsing back to zero.
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Tay says this big crunch defines the end of the universe,
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and he says that'll happen in around twenty billion years
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from now. The findings are based on observations by the
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Dark Energy Survey in Chile and the Dark Energy Spectroscopic
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Instrument DESI in Arizona, which are both in good accord
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with each other's data. The whole idea of the dark
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energy survey of these two groups is to see whether
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dark energy, which makes up roughly sixty eight percent of
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the mass energy budget of the universe, really comes from
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a pure cosmological constant. The authors found that the universe
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is not just dominated by a cosmological constant known as
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dark energy. Tying colleagues proposed, there's a hypothetical particle of
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very low mass that behave like a cosmological consper than
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early in the life of the universe.
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But doesn't anymore.
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And it's this simple model which fits the data so
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well and tips the underlying cosmological constant into negative territory,
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ty says. Scientists have said before that if the cosmological
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constant is negative, then the universe would eventually collapse. That's
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not new, However, here the model tells you when the
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universe collapses and how it collapses. Hundreds of astronomers are
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busy measuring dark energy by observing millions of galaxies across
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the cosmos and determining the distance between these galaxies, gathering
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more and more accurate data to feed into the model.
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DESI will continue observations for another year, and observations are
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ongoing or soon begin with several other dark energy observatories,
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including the Zvicki Transient Facility in San Diego, the European
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EUCLID Space Telescope, NASA's recently launched sphere X mission, and
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the Vericea group in Observatory TI says knowing both the
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beginning and the end of the universe provides a great
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or understanding of the cosmos. As to where the universe
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goes once it contracts down into a big crunch, Well,
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the answer is simple.
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The universe goes into the future. This is space time.
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Still to come, a new three dimensional map of our
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Milky Way Galaxy and how fun Guy set the stage
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for life on land on planet Earth.
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All that and more still to come on space time.
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The European Space Agency's Guyas Space Telescope has created the
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most accurate three dimensional map yet of star forming regions
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in our Milky Way Galaxy. This new map will teach
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astronomer's more about these obscure molecular gas and dust clouds
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and the hot young stars born within them and which
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ultimately shape them tooriously difficult to map and steady regions
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of space where stars form because they're usually hidden from
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view by thick clouds whose distances cannot be accurately directly measured.
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Now guy itself doesn't see these clouds, but it can
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measure stillar positions and the so called extinction of stars.
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This means it can see how much light from the
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star is being blocked by dust. From this, astronomers can
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create three dimensional maps showing where the dust is and
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use those maps to figure out how much ionized gas
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is present, a telltale sign of star formation. The new
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three dimensional map of star forming regions in the Milky
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Way is based on guyer observations of some forty four
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million ordinary stars and eighty seven spectroal typezer blue stars.
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The map extends out to a distance of some four
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thousand light years. Spectral type O blue stars are rare.
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They're young, massive, and extremely bright and hot, and they
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shine bright in ultraviolet light. These ultraviolet photons are so
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energetic they can quite literally strip electrons away from hydrogen
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atoms when hitting them. In this way, they ionize the
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hydrogen gas around hot stars mini becomes a mixture of
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charched particles. Astronomers call these ionized hydrogen clouds hydrogen two regions.
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The characteristic signal that can be picked up from these
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regions is the hydrogen alpha or H alpha spectral line
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at a wavelength of six hundred and fifty six point
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three nanometers. This is one way that astronomers can identify
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regions in space where stars are being born. Many telescopes
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have observed these regions, so astronomers have a good idea
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of what they look like, but no one really knew
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what they look like in three dimensions or from an
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outside perspective, and that's where Guy comes in. Geya has
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mapped the positions of velocities and motions across the sky
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of billions of celestial objects, including millions of stars. The
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result is the most accurate multi dimensional map of the
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Milky Way galaxy ever created, and it's giving astronomers the
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data to infer what the galaxy would look like from
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the perspective of someone outside the Milky Way. Guys sky
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maps in all three special coordinates plus three velocities that
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he's moving towards or away from the Earth and moving
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across the sky have revealed the precise merchants and positions
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of millions of nearby stars. With this the telescope's already
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revolutionized sciences view of the soular neighborhood, allowing astronomers to
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comprehensively map the stars and interstellar material near the Sun
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in a way that they were simply unable to do before.
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One of the studies authors, Lewis McCallum from the University
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of s Andrews, says, Guy is providing the first accurate
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view of what our section of the Milky Way galaxy
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really would look like from above. He says, there's simply
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never been a model of the distribution of ionized gas
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in the local Milky Way that matches other telescope's observations
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of the sky so well. That's why astronomers are so
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confident that guys top down view and fly through the
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galaxy are a good approximation of what these clouds would
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really look like in three dimensions. Lewis's new map included
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its three dimensional views of the Gum Nebula, the North
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American Nebula, the California Nebula, and the Orion Eridanus superbubble.
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This data will allow astronomers to learn more about how
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giant spectrotype O stars energize gas and how far out
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their influence can reach. Laws and colleagues already notice that
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some of the clouds in the star forming regions seem
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to have broken open, and streams of gas and dust
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are likely venting into a giant cavity. The map also
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shows how radiation from massive stars ionizes the surrounding interstellar medium,
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and how dust and gas interact with this radiation. The
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three D model provides a detailed look at the processes
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that shape our local galactic environment, and it helps astronomers
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better understand interactions between the warm and cold components of
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the local universe. In the future, this map, which requires
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huge computational power to develop, will expand even further, including
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an even larger area of our home galaxy.
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This report from east.
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What does the Milky Way look like from the outside.
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No spacecraft can travel beyond our galaxy, so we can't
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take a selfie. But during its lifetime, Gaya made three
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trillion observations of two billion stars and other objects, giving
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us the best insight yet of what our home galaxy
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looks like. We can identify the Milky Way's central bar
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and its spiral arms based on Gaya data. Going see
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the galaxy edge on and it can identify its pulg
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and disk. Gaya showed that our galaxy's disc is warped
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in wobbles, possibly caused by a collision with another smaller
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galaxy moving further out. Gaya also studied other galaxies around
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the Milky Way, such as the large and the small
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Midgellanic Clouds and forty other companions. Guya revealed our galaxy's
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turbulent history by tracking the movements of streams of stars.
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Gaya gives a unique view of our milchury, scanning our
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galaxy from the inside out, building a more detailed map
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than ever before, fundamentally changing what we thought we knew
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about our home galaxy, where our sun is embedded among
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billions of stars.
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This is space time still to come, how fungals set
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the stage for life on land on planet Earth. And
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Later in the science report, a new study says people
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whose parents have mental illnesses are more likely to die prematurely.
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All that and more still to come on space time.
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A new study examining life save evolution on planet Earth.
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It's found that fung guy set the stage for life
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on land somewhere between nine hundred million and one point
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four billion years ago, so that's hundreds of millions of
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years earlier than previously thought. The findings were reported in
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the journal Nature of collogen Evolution used a novel gene
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swamp method to shed new light on the timelines and
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pathways for the evolution of fungi. The discovery, but researchers
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from the Okinawa Institute of Science and Technology, provides evidence
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for the evolution of fungi run terrestrial ecosystems, and therefore
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the emergence of life on land. It suggests these ecosystems
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recycled nutrients and possibly partnered with other organisms. Pinning down
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their timelines shows fungi with diversifying long before plants and
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consistent with early partnerships with algae that likely help pave
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the way for terrestrial ecosystems. Complex multicellular life, that is,
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organisms made from many cooperating cells with specialized jobs, evolved
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independently on Earth on at least five major occasions, animals, land, plants, fungi,
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red algae, and brown algae. Understanding when these groups emerged
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is fundamental to piecing together the history of life on Earth.
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See Complex multicelluar life wasn't simply a matter of cells
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clamping together. It was the dawn of organisms, where cells
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took on specialized jobs and were organized into distinct tissues
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and organs. For most of these groups, the fossil record
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acts as a geological calendar, providing anchor points in deep time.
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For example, red algae shows up as early as one
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point six billion years ago in candidate seaweed like fossils
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from India. Animals appeared around six hundred million years ago
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based on idiakron fossils such the quilted pancake like Dickensernia.
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The first land plants took roughly four.
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Hundred and seventy million years ago based on the discovery
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of tiny fossil spores and brown algae such as kelp.
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Diversified tens to hundreds of million years later. Still, and
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based on all this evidence, a chronological picture of life's
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complexity starts to emerge. But the notable exception to this
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fossil based timeline has always been fungi. The fungal kingdom
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has long been an enigma for paleontologists. They are typically soft,
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filamentalist bodies means they really fossilize well and Unlike animals
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or plants, which appear to have a single origin of
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complex multicellularity, it seems fungi evolved that's trait mudiple times
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from the verse unicellular ancestors, making it difficult to pinpoint
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a single origin event in the fossil record. To overcome
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the gaps in the fungal fossil record, scientists are relying
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on the steady rate at which genic mutations accumulate in
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an organism's DNA for generations. By comparing the number of
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genetic differences between two species, scientists can reach an estimate
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of how long ago they diverged from a common ancestor.
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The problem is this molecular clock still uncalibrated. It can
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reveal relative time, but not absolute years. To set the clock,
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scientists need to calibrate it with anchor points from the
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fossil record, and given the scarcity of fungal fossils, this
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has always been a major challenge. The new study addressed
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this incorporating rare gene swaps between different fungal lineages, a
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process known as horizontal gene transfer. While genes are normally
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passed down vertically from parent to child, horizontal gene transfer
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is like a gene jumping sideways from one species to another,
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and if a gene from LINEA J is found to
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have jumped into lineage B, it establishes a clear rule
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the ancestors of linea J must be older than the
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descendants of lineage B. By identifying seventeen such transfers, the
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authors established a series of older than younger than relationships
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at Alongside fossil records have helped to tighten and constrain
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the fungal timeline. The analysis suggests a common ancestor for
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living fungal dating to between roughly nine hundred million a
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one point four billion years ago. That's rule before land plants.
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That timing supports a long prelude of fungal algae interactions,
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fundamentally reframing the story of life's colonization of land. It
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suggests that for hundreds of millions of years before the
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first true plants took root, fungi were already present, likely
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interacting with algae in microbial communities, and this long preparatory
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phase may will have been essential for making Earth's continents
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habitable by breaking down rock and recycling nutrients. These ancient
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fungi may well have been the first true ecosystems engineers,