Results 1 to 10 of 10

Thread: Dyson Spheres in recent news

  1. #1
    Join Date
    Sep 2004
    Posts
    3,199

    Exclamation Dyson Spheres in recent news

    https://arxiv.org/abs/1804.08351

    SETI with Gaia: The observational signatures of nearly complete Dyson spheres

    Erik Zackrisson, Andreas J. Korn, Ansgar Wehrhahn, Johannes Reiter
    (Submitted on 23 Apr 2018 (v1), last revised 1 Jul 2018 (this version, v2))

    A star enshrouded in a Dyson sphere with high covering fraction may manifest itself as an optically subluminous object with a spectrophotometric distance estimate significantly in excess of its parallax distance. Using this criterion, the Gaia mission will in coming years allow for Dyson-sphere searches that are complementary to searches based on waste-heat signatures at infrared wavelengths. A limited search of this type is also possible at the current time, by combining Gaia parallax distances with spectrophotometric distances from ground-based surveys. Here, we discuss the merits and shortcomings of this technique and carry out a limited search for Dyson-sphere candidates in the sample of stars common to Gaia Data Release 1 and RAVE Data Release 5. We find that a small fraction of stars indeed display distance discrepancies of the type expected for nearly complete Dyson spheres. To shed light on the properties of objects in this outlier population, we present follow-up high-resolution spectroscopy for one of these stars, the late F-type dwarf TYC 6111-1162-1. The spectrophotometric distance of this object is about twice that derived from its Gaia parallax, and there is no detectable infrared excess. While our analysis largely confirms the stellar parameters and the spectrophotometric distance inferred by RAVE, a plausible explanation for the discrepant distance estimates of this object is that the astrometric solution has been compromised by an unseen binary companion, possibly a rather massive white dwarf (≈1 M ⊙ ). This scenario can be further tested through upcoming Gaia data releases.

  2. #2
    Join Date
    Sep 2004
    Posts
    3,199
    Let's talk about big friendly Dyson Spheres.


    http://cdsads.u-strasbg.fr/abs/2018arXiv180700077L

    Sunscreen: Photometric Signatures of Galaxies Partially Cloaked in Dyson Spheres

    Lacki, Brian C.
    06/2018

    SETI searches have so far come up negative for Kardashev Type III societies that capture all starlight from a galaxy. One possible reason is that shrouding a star in a megastructure is prohibitively expensive. Most of a galaxy's starlight comes from bright stars, which would require structures even larger than the classical Dyson sphere to enclose. Using a custom spectral synthesis code, I calculate what happens to the spectrum and colors of a galaxy when only stars below a luminosity L_min are cloaked. I find the photometric signatures of galaxies with L_min <= 1 L_sun are minor, especially for blue, late-type galaxies. Larger luminosity thresholds (>~ 30 L_sun) result in galaxies with unnatural colors and luminosities. Late-type galaxies in NIR and early-type galaxies at UV-NIR wavelengths become redder than uncloaked galaxies as L_min increases. Late-type galaxies get bluer in UV and blue light when they are cloaked, with colors similar to quasars but very low luminosities. By selecting on color, we may find Type III societies in large photometric surveys. I discuss how different metallicities, ages, and initial mass functions affect the results.

    ===========================

    http://cdsads.u-strasbg.fr/abs/2018arXiv180605203H

    Life Versus Dark Energy: How An Advanced Civilization Could Resist the Accelerating Expansion of the Universe

    Hooper, Dan
    06/2018

    The presence of dark energy in our universe is causing space to expand at an accelerating rate. As a result, over the next approximately 100 billion years, all stars residing beyond the Local Group will fall beyond the cosmic horizon and become not only unobservable, but entirely inaccessible, thus limiting how much energy could one day be extracted from them. Here, we consider the likely response of a highly advanced civilization to this situation. In particular, we argue that in order to maximize its access to useable energy, a sufficiently advanced civilization would chose to expand rapidly outward, build Dyson Spheres or similar structures around encountered stars, and use the energy that is harnessed to accelerate those stars away from the approaching horizon and toward the center of the civilization. We find that such efforts will be most effective for stars with masses in the range of $M\sim (0.2-1) M_{\odot}$, and could lead to the harvesting of stars within a region extending out to several tens of Mpc in radius, potentially increasing the total amount of energy that is available to a future civilization by a factor of several thousand. We also discuss the observable signatures of a civilization elsewhere in the universe that is currently in this state of stellar harvesting.

    ==========================

    http://cdsads.u-strasbg.fr/abs/2018ApJ...859...40I

    Searching for Exoplanets around X-Ray Binaries with Accreting White Dwarfs, Neutron Stars, and Black Holes

    Imara, Nia; Di Stefano, Rosanne
    05/2018

    We recommend that the search for exoplanets around binary stars be extended to include X-ray binaries (XRBs) in which the accretor is a white dwarf, neutron star, or black hole. We present a novel idea for detecting planets bound to such mass transfer binaries, proposing that the X-ray light curves of these binaries be inspected for signatures of transiting planets. X-ray transits may be the only way to detect planets around some systems, while providing a complementary approach to optical and/or radio observations in others. Any planets associated with XRBs must be in stable orbits. We consider the range of allowable separations and find that orbital periods can be hours or longer, while transit durations extend upward from about a minute for Earth-radius planets, to hours for Jupiter-radius planets. The search for planets around XRBs could begin at once with existing X-ray observations of these systems. If and when a planet is detected around an X-ray binary, the size and mass of the planet may be readily measured, and it may also be possible to study the transmission and absorption of X-rays through its atmosphere. Finally, a noteworthy application of our proposal is that the same technique could be used to search for signals from extraterrestrial intelligence. If an advanced exocivilization placed a Dyson sphere or similar structure in orbit around the accretor of an XRB in order to capture energy, such an artificial structure might cause detectable transits in the X-ray light curve.

    ========================

    http://cdsads.u-strasbg.fr/abs/2018IJAsB..17..112O

    Are the Dyson rings around pulsars detectable?

    Osmanov, Z.
    04/2018

    In the previous paper ring (Osmanov 2016) (henceforth Paper-I) we have extended the idea of Freeman Dyson and have shown that a supercivilization has to use ring-like megastructures around pulsars instead of a spherical shell. In this work we reexamine the same problem in the observational context and we show that facilities of modern infrared (IR) telescopes (Very Large Telescope Interferometer and Wide-field Infrared Survey Explorer (WISE)) might efficiently monitor the nearby zone of the solar system and search for the IR Dyson-rings up to distances of the order of 0.2 kpc, corresponding to the current highest achievable angular resolution, 0.001 mas. In this case the total number of pulsars in the observationally reachable area is about 64 +/- 21. We show that pulsars from the distance of the order of ~ 1 kpc are still visible for WISE as point-like sources but in order to confirm that the object is the neutron star, one has to use the ultraviolet telescopes, which at this moment cannot provide enough sensitivity.

    =========================

    http://cdsads.u-strasbg.fr/abs/2018arXiv180404157O

    On the possibility of the Dyson spheres observable beyond the infrared spectrum

    Osmanov, Z.; Berezhiani, V. I.
    04/2018

    In this paper we revisit the Dysonian approach and assume that a superadvanced civilisation is capable of building a cosmic megastructure located closer than the habitable zone (HZ). Then such a Dyson Sphere (DS) might be visible in the optical spectrum. We have shown that for typical high melting point meta material - Graphene, the radius of the DS should be of the order of $10^{11}$cm, or even less. It has been estimated that energy required to maintain the cooling system inside the DS is much less than the luminosity of a star. By considering the stability problem, we have found that the radiation pressure might stabilise dynamics of the megastructure and as a result it will oscillate, leading to interesting observational features - anomalous variability. The similar variability will occur by means of the transverse waves propagating along the surface of the cosmic megastructure. In the summary we also discuss the possible generalisation of definition of HZs that might lead to very interesting observational features.

  3. #3
    Join Date
    Sep 2004
    Posts
    3,199
    Going back to 2016.... far enough....

    http://cdsads.u-strasbg.fr/abs/2017SoSyR..51..422K

    Heritage of the Kepler mission: Special object KIC 8462852 and criticism of the cometary hypothesis

    Ksanfomality, L. V.; Tavrov, A. V.
    09/2017

    Paradoxical properties of the KIC 8462852 object discovered in the course the Kepler mission are considered. It has been shown that the assumptions about the nature of the object as a swarm of cometary bodies, fragments resulting from catastrophic collisions of asteroids, or the KIC 8462852b exoplanet meet serious problems and even contradict the Kepler laws, if the eclipsing object is considered as a physical body orbiting a central star. According the energy and other requirements, the hypothetical orbit of KIC 8462852b does not meet the Dyson sphere conception either. In the paper, we used the materials of the study by Boyajian et al. (2015) and the subsequent publications on this theme.

    ==============================

    http://cdsads.u-strasbg.fr/abs/2017LPICo1967.4154H

    Fuller Clarke Sphere

    Heckman, T.; Pravdo, S.
    07/2017

    A Geodesic Sphere constructed around the planet for defense, scientific study, urban, commercial and industrial use analogous to a Dyson Sphere. Clarke Space Elevators are also implemented in the design located at the icosahedral vertex points.

    ===============================

    http://cdsads.u-strasbg.fr/abs/2017ARep...61..347K

    Some properties of the companions of KIC 8462852 (based on KEPLER data)

    Ksanfomality, L. V.
    04/2017

    The properties of the object KIC 8462852 or its exoplanets, discovered in the KEPLERmission, remain unexplained. The hypotheses that the object is a swarm of cometary bodies, wreckage from a catastrophic collision of asteroids, or an exoplanet KIC 8462852b encounter serious difficulties, and even contradictions with Kepler's laws, if the eclipsing object is taken to be a physical body revolving around the central star. The hypothetical orbit of KIC 8462852b does not correspond to the expectations for a Dyson sphere in terms of energetic and other requirements. The mass characteristics of the eclipsing object remain unknown. Material from Boyajian et al. (2015) and subsequent publications on this topic are used.

    =============================

    http://cdsads.u-strasbg.fr/abs/2017AmJPh..85...14O

    Life under a black sun

    Opatrný, Tomáš; Richterek, Lukáš; Bakala, Pavel
    01/2017

    Life is dependent on the income of energy with low entropy and the disposal of energy with high entropy. On Earth, the low-entropy energy is provided by solar radiation and the high-entropy energy is disposed of as infrared radiation emitted into cold space. Here, we turn the situation around and imagine the cosmic background radiation as the low-entropy source of energy for a planet orbiting a black hole into which the high-entropy energy is expelled. We estimate the power that can be produced by thermodynamic processes on such a planet, with a particular interest in planets orbiting a fast rotating Kerr black hole as in the science fiction movie Interstellar. We also briefly discuss a reverse Dyson sphere absorbing cosmic background radiation from the outside and dumping waste energy to a black hole inside.

    =====================================

    http://cdsads.u-strasbg.fr/abs/2016IJAsB..15..127O

    On the search for artificial Dyson-like structures around pulsars

    Osmanov, Z.
    04/2016

    Assuming the possibility of existence of a supercivilization we extend the idea of Freeman Dyson considering pulsars instead of stars. It is shown that instead of a spherical shell the supercivilization must use ring-like constructions. We have found that a size of the `ring' should be of the order of (10-4-10-1) AU with temperature interval (300-600) K for relatively slowly rotating pulsars and (10-350) AU with temperature interval (300-700) K for rapidly spinning neutron stars, respectively. Although for the latter the Dyson construction is unrealistically massive and cannot be considered seriously. Analyzing the stresses in terms of the radiation and wind flows it has been argued that they cannot significantly affect the ring construction. On the other hand, the ring in-plane unstable equilibrium can be restored by the energy which is small compared with the energy extracted from the star. This indicates that the search for infrared ring-like sources close to slowly rotating pulsars seems to be quite promising.

  4. #4
    Join Date
    Sep 2004
    Posts
    3,199
    "Life Under a Black Sun" … okay, that is super weird.

  5. #5
    Join Date
    Sep 2004
    Posts
    3,199
    Solution to the end of the universe: build more Dyson spheres!


    https://arxiv.org/abs/1806.05203

    Life Versus Dark Energy: How An Advanced Civilization Could Resist the Accelerating Expansion of the Universe

    Dan Hooper (Submitted on 13 Jun 2018)

    The presence of dark energy in our universe is causing space to expand at an accelerating rate. As a result, over the next approximately 100 billion years, all stars residing beyond the Local Group will fall beyond the cosmic horizon and become not only unobservable, but entirely inaccessible, thus limiting how much energy could one day be extracted from them. Here, we consider the likely response of a highly advanced civilization to this situation. In particular, we argue that in order to maximize its access to useable energy, a sufficiently advanced civilization would chose to expand rapidly outward, build Dyson Spheres or similar structures around encountered stars, and use the energy that is harnessed to accelerate those stars away from the approaching horizon and toward the center of the civilization. We find that such efforts will be most effective for stars with masses in the range of M∼(0.2−1)M ⊙ , and could lead to the harvesting of stars within a region extending out to several tens of Mpc in radius, potentially increasing the total amount of energy that is available to a future civilization by a factor of several thousand. We also discuss the observable signatures of a civilization elsewhere in the universe that is currently in this state of stellar harvesting.


    [oops, already posted. will be more careful. REM]

  6. #6
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    37,003
    Couldn't help but notice, almost all of these articles refer to a "Dyson Sphere" as if it were a solid shell, and not Dyson's original conception of an orbital swarm. In particular, Osmanov makes this mistake more than once.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  7. #7
    Join Date
    Sep 2004
    Posts
    3,199
    Speaking of Dyson Spheres and Kardashev Type-III cultures...

    https://arxiv.org/abs/1807.00077

    Sunscreen: Photometric Signatures of Galaxies Partially Cloaked in Dyson Spheres

    Brian C. Lacki (Submitted on 29 Jun 2018 (v1), last revised 16 Jan 2019 (this version, v2))

    The Search for Extraterrestrial Intelligence has so far come up negative for Kardashev Type III societies that capture all starlight from a galaxy. One possible reason is that shrouding a star in a megastructure is prohibitively expensive. Most of a galaxy's starlight comes from bright stars, which would require structures even larger than the classical Dyson sphere to enclose. Using a custom spectral synthesis code, I calculate what happens to the spectrum and colors of a galaxy when only stars below a luminosity L_min are cloaked. I find the photometric signatures of galaxies with L_min <= 1 L_sun are minor, especially for blue, galaxies with continuing star formation. Larger luminosity thresholds (>~ 30 L_sun) result in galaxies with unnatural colors and luminosities. Galaxies observed in NIR and galaxies without recent star formation observed at UV-NIR wavelengths become redder than uncloaked galaxies as L_min increases. Recently star-forming galaxies get bluer in UV and blue light when they are cloaked, with colors similar to quasars but very low luminosities. By selecting on color, we may find Type III societies in large photometric surveys. I discuss how different metallicities, ages, and initial mass functions affect the results.

    ===

    https://arxiv.org/abs/1903.12186

    Fast Radio Bursts from Terraformation

    Almog Yalinewich, Mubdi Rahman, Alysa Obertas, Patrick C. Breysse

    (Submitted on 28 Mar 2019)

    Fast radio bursts (FRBs) are, as the name implies, short and intense pulses of radiation at wavelengths of roughly one metre. FRBs have extremely high brightness temperatures, which points to a coherent source of radiation. The energy of a single burst ranges from 10 36 to 10 39 erg. At the high end of the energy range, FRBs have enough energy to unbind an earth-sized planet, and even at the low end, there is enough energy to vaporise and unbind the atmosphere and the oceans. We therefore propose that FRBs are signatures of an artificial terraformer, capable of eradicating life on another planet, or even destroy the planet entirely. The necessary energy can be harvested from Wolf-Rayet stars with a Dyson sphere (∼10 38 erg s −1 ) , and the radiation can be readily produced by astrophysical masers. We refer to this mechanism as Volatile Amplification of a Destructive Emission of Radiation (VADER). We use the observational information to constrain the properties of the apparatus. We speculate that the non-repeating FRBs are low-energy pulses used to exterminate life on a single planet, but leaving it otherwise intact, and that the stronger repeating FRB is part of an effort to destroy multiple objects in the same solar system, perhaps as a preventative measure against panspermia. In this picture, the persistent synchrotron source associated with the first repeating FRB arises from the energy harvesting process. Finally we propose that Oumuamua might have resulted from a destruction of a planet in this manner.

  8. #8
    Join Date
    Sep 2004
    Posts
    3,199
    This article was recently mentioned in another thread, but it is relevant here as neutrino transmitters (for communication) could only be built by Dyson Sphere cultures, according to this author.

    https://arxiv.org/abs/1905.05184

    A Neutrino Beacon

    A.A. Jackson (Submitted on 13 May 2019 (v1), last revised 15 May 2019 (this version, v2))

    Observational SETI has concentrated on using electromagnetism as the carrier , namely radio waves and laser radiation. Michael Hippke [2] has pointed out that it may be possible to use neutrinos or gravitational waves as signals. Gravitational waves demand the command of the generation of very large scale amounts of energy, Jackson and Benford [3]. This paper describes a beacon that uses beamed neutrinos as the signal. Neutrinos, like gravitational waves, have the advantage of extremely low extinction in the interstellar medium. To make use of neutrinos an advanced civilization can use a gravitational lens as a focus and amplifier. The lens can be a neutron star or a black hole. Using wave optics one can calculate the advantage of gravitational lensing for amplification of a beam and along the optical axis it is exceptionally large. Even though the amplification is very large the dimeter of the beam is quite small, less that a centimeter. This implies that a large constellation of neutrino transmitters would have to enclose the local neutron star or black hole to cover the sky. This means that such a beacon would have to be built by a Kardashev Type II civilization.

  9. #9
    Join Date
    Aug 2005
    Location
    NEOTP Atlanta, GA
    Posts
    2,814
    Quote Originally Posted by Roger E. Moore View Post
    Speaking of Dyson Spheres and Kardashev Type-III cultures...

    https://arxiv.org/abs/1903.12186

    Fast Radio Bursts from Terraformation

    Almog Yalinewich, Mubdi Rahman, Alysa Obertas, Patrick C. Breysse

    (Submitted on 28 Mar 2019)

    Fast radio bursts (FRBs) are, as the name implies, short and intense pulses of radiation at wavelengths of roughly one metre. FRBs have extremely high brightness temperatures, which points to a coherent source of radiation. The energy of a single burst ranges from 10 36 to 10 39 erg. At the high end of the energy range, FRBs have enough energy to unbind an earth-sized planet, and even at the low end, there is enough energy to vaporise and unbind the atmosphere and the oceans. We therefore propose that FRBs are signatures of an artificial terraformer, capable of eradicating life on another planet, or even destroy the planet entirely. The necessary energy can be harvested from Wolf-Rayet stars with a Dyson sphere (∼10 38 erg s −1 ) , and the radiation can be readily produced by astrophysical masers. We refer to this mechanism as Volatile Amplification of a Destructive Emission of Radiation (VADER). We use the observational information to constrain the properties of the apparatus. We speculate that the non-repeating FRBs are low-energy pulses used to exterminate life on a single planet, but leaving it otherwise intact, and that the stronger repeating FRB is part of an effort to destroy multiple objects in the same solar system, perhaps as a preventative measure against panspermia. In this picture, the persistent synchrotron source associated with the first repeating FRB arises from the energy harvesting process. Finally we propose that Oumuamua might have resulted from a destruction of a planet in this manner.
    Sounds like the premise - or a plot device at least - for a Larry Niven novel.

  10. #10
    Join Date
    Sep 2004
    Posts
    3,199
    Quote Originally Posted by schlaugh View Post
    Sounds like the premise - or a plot device at least - for a Larry Niven novel.
    Alas, I realize now that the paper was an April Fool's jest. (The "VADER" device, submitted right before April 1...)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •