5 ms·

> “The alien-megastructure idea runs wrong with my new observations,” he says, as he thinks even advanced aliens wouldn’t be able to build something capable of

> “The alien-megastructure idea runs wrong with my new observations,” he says, as he thinks even advanced aliens wouldn’t be able to build something capable of covering a fifth of a star in just a century. Oh, really? So we are speaking for alien's abilities now because we don't believe in them or their abilities to build things? That sounds like a cognitive bias. Here's another bias in the same vein: > “No flying machine will ever fly from New York to Paris …[because] no known motor can run at the requisite speed for four days without stopping.” - Orville Wright What Orville should have said was, "No flying machine will fly from New York to Paris until we develop a motor that can run at the required speed without stopping until it gets there."

WiseWeasel 11y ago
And his second justification is even more baffling: > "What’s more, such an object should radiate light absorbed from the star as heat, but the infrared signal from Tabby’s star appears normal, he says." As if intelligent beings with an interest in capturing a fifth of a star's output would only be absorbing the human-visible spectrum of its radiance.
- idlewords 11y ago
  It's a thermodynamic argument, not an anthropocentric one. Irrespective of your technology, you can't just absorb all the energy of a star without re-radiating it, unless you want to cook yourself inside a gigantic space thermos.
  - WiseWeasel 11y ago
    Unless you can store, transmit and use it in a way that doesn't radiate energy omnidirectionally. My guess: universe's biggest indoor pot grow.
    - idlewords 11y ago
      "Bro, point it away from that planet. That place is crawling with cops!"
  - sandworm101 11y ago
    Perhaps they are bouncing all that energy off-axis. That we cannot see the light doesn't mean it doesn't exist. Perhaps they are reflecting it back on the star for some reason. Or maybe we are seeing a mirror that is pushing some interstellar ship away from the host star. Luckily for us it would be traveling perpendicular to our vantage point, ie not coming here. Perhaps we should be looking for a mobile IR emitter somewhere nearby but accelerating away from this star. (I call dibs on the naming rights!)
    - jschwartzi 11y ago
      You wouldn't be able to direct all of it off-axis. In order to do any meaningful work with it, some of it must be lost as heat or the entropy of the universe does not increase. That would violate the laws of thermodynamics. Essentially, you can reduce the entropy of an isolated collection of particles, but only at the expense of increasing the entropy of another collection of atoms, and only if you move the entropy around. There's a slim possibility that a sufficiently advanced civilization has improved the efficiency of their process sufficiently to the point where the thermal radiation isn't measurable with our technology, but there still must be thermal radiation if any meaningful work is being done with the harvested energy.
      - sandworm101 11y ago
        Yes, but not necessarily thermal radiation aimed in the narrow direction necessary for us to detect it. Thermodynamics does not guarantee that all necessary information propagate in nice measurable spheres for all to see equally.
  - krapp 11y ago
    >unless you want to cook yourself inside a gigantic space thermos Or cook someone else.
  - mrfusion 11y ago
    Couldn't you store the energy? Perhaps as antimatter?
    - idlewords 11y ago
      Not without generating waste heat. It's a fundamental law of nature.
      - mrfusion 11y ago
        Right but you don't have to reradiate all the energy.
        ars 11y ago
        You kind of do. Energy available is a function of the difference between the input and output energy. You can do useful work with the difference. It's not possible to harvest everything without also emitting some.
SixSigma 11y ago
The R100 [1] that flew from the UK to Canada in 1930 in 72 hours used 6 of these monsters [2] in Wright's lifetime : Dry weight: 1,380 lb (628 kg) Power output: 670 bhp (500 kW) at 1,900 rpm I wonder how he felt then [1] https://en.wikipedia.org/wiki/R100 https://en.wikipedia.org/wiki/R100 [2] https://en.wikipedia.org/wiki/Rolls-Royce_Condor https://en.wikipedia.org/wiki/Rolls-Royce_Condor
- lmm 11y ago
  Not the same kind of flying machine - in an airship you can turn off the engines for a while if need be. But as early as 1919 you have https://en.wikipedia.org/wiki/Transatlantic_flight_of_Alcock_and_Brown https://en.wikipedia.org/wiki/Transatlantic_flight_of_Alcock...

WiseWeasel 11y ago

And his second justification is even more baffling: > "What’s more, such an object should radiate light absorbed from the star as heat, but the infrared signal from Tabby’s star appears normal, he says." As if intelligent beings with an interest in capturing a fifth of a star's output would only be absorbing the human-visible spectrum of its radiance.

idlewords 11y ago
It's a thermodynamic argument, not an anthropocentric one. Irrespective of your technology, you can't just absorb all the energy of a star without re-radiating it, unless you want to cook yourself inside a gigantic space thermos.
- WiseWeasel 11y ago
  Unless you can store, transmit and use it in a way that doesn't radiate energy omnidirectionally. My guess: universe's biggest indoor pot grow.
  - idlewords 11y ago
    "Bro, point it away from that planet. That place is crawling with cops!"
- sandworm101 11y ago
  Perhaps they are bouncing all that energy off-axis. That we cannot see the light doesn't mean it doesn't exist. Perhaps they are reflecting it back on the star for some reason. Or maybe we are seeing a mirror that is pushing some interstellar ship away from the host star. Luckily for us it would be traveling perpendicular to our vantage point, ie not coming here. Perhaps we should be looking for a mobile IR emitter somewhere nearby but accelerating away from this star. (I call dibs on the naming rights!)
  - jschwartzi 11y ago
    You wouldn't be able to direct all of it off-axis. In order to do any meaningful work with it, some of it must be lost as heat or the entropy of the universe does not increase. That would violate the laws of thermodynamics. Essentially, you can reduce the entropy of an isolated collection of particles, but only at the expense of increasing the entropy of another collection of atoms, and only if you move the entropy around. There's a slim possibility that a sufficiently advanced civilization has improved the efficiency of their process sufficiently to the point where the thermal radiation isn't measurable with our technology, but there still must be thermal radiation if any meaningful work is being done with the harvested energy.
    - sandworm101 11y ago
      Yes, but not necessarily thermal radiation aimed in the narrow direction necessary for us to detect it. Thermodynamics does not guarantee that all necessary information propagate in nice measurable spheres for all to see equally.
- krapp 11y ago
  >unless you want to cook yourself inside a gigantic space thermos Or cook someone else.
- mrfusion 11y ago
  Couldn't you store the energy? Perhaps as antimatter?
  - idlewords 11y ago
    Not without generating waste heat. It's a fundamental law of nature.
    - mrfusion 11y ago
      Right but you don't have to reradiate all the energy.
      - ars 11y ago
        You kind of do. Energy available is a function of the difference between the input and output energy. You can do useful work with the difference. It's not possible to harvest everything without also emitting some.

SixSigma 11y ago

The R100 [1] that flew from the UK to Canada in 1930 in 72 hours used 6 of these monsters [2] in Wright's lifetime : Dry weight: 1,380 lb (628 kg) Power output: 670 bhp (500 kW) at 1,900 rpm I wonder how he felt then [1] https://en.wikipedia.org/wiki/R100 https://en.wikipedia.org/wiki/R100 [2] https://en.wikipedia.org/wiki/Rolls-Royce_Condor https://en.wikipedia.org/wiki/Rolls-Royce_Condor

lmm 11y ago
Not the same kind of flying machine - in an airship you can turn off the engines for a while if need be. But as early as 1919 you have https://en.wikipedia.org/wiki/Transatlantic_flight_of_Alcock_and_Brown https://en.wikipedia.org/wiki/Transatlantic_flight_of_Alcock...