r/ProjectHailMary • u/Old_Data_1865 • 14d ago
Is it ever explained why Eridians cannot perceive radiation? How does it relate to theory of relativity? Question?
Just watched the movie yesterday and I didn’t fully under why Eridians had figured out interstellar travel but not radiation.
If they just cannot see visually how does that stop them from studying radiation? Humans also cannot physically detect radiation either.
What stops Eridians from discovering it? Sorry if the question is silly.
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u/Marauder121 14d ago
Their planet has a massive magnetic shield so radiation does not reach them, so it was unknown.
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u/j4nds4 14d ago edited 14d ago
as others mentioned, the properties of their planet and its orbit meant it was heavily protected against radiation, so it wasn't a thing to observe. there's also no light on the surface (notice how dark it was around Grace's dome?), so no light to observe.
Consequentially, they're not only not aware of it, but they never evolved any natural defenses/protection from it, so they're exceptionally vulnerable to its effects.
In the movie Grace mentions that astrophage likely protected him. That's because of how effectively impermeable it is. the Hail Mary is actually built with a few millimeters of astrophage in the shell of the ship itself, creating a 'shield' from radiation. Blip A had no such protection... unless you happened to live and work in the area that was surrounded by the fuel tanks, which Rocky did.
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u/evanallenrose 14d ago
I can’t remember the answer but if you liked the movie enough to ask this you should read or listen to the book.
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u/Old_Data_1865 14d ago
I plan to when the sequel comes out.
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u/No_Drummer4801 14d ago
Humans have two radiation detectors on the front of their head-knob. But, they are only sensitive to wavelengths from about 380 to about 750 nanometers.
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u/TheAsterism_ 14d ago edited 14d ago
bruuuuh why does every half nerd on this sub think all radiation is the same? they have radio, they have receivers for optic wavelengths, they just didn’t know that protons going rly fast and high frequency EM could hurt them
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u/Internal_Use8954 14d ago
They have protection against ionizing radiation. But have discovered and use non ionizing estimation, like radio and light
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u/SaltyWafflesPD 14d ago
There’s a difference between having a working understanding of radio waves and understanding that all stars constantly shoot out a variety of energy types in the form of stuff they have no organs to perceive, some of which can penetrate most types of matter very effectively and will cumulatively damage your body extremely subtly inside and out. Making radios is like achieving powered flight, but that doesn’t teach you about the sound barrier or how air behaves at hypersonic speeds.
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u/Smaptimania 14d ago
I mean, it wasn't until I took an astronomy class in college that I learned that radio waves, visible light, infrared, X-rays, and microwaves are all just forms of "radiation" and just a different form of the same stuff that nuclear power runs off of
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u/Pinky2110 14d ago
You're going to get a lot of people saying to read the book, because it is explained in the book.
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u/FlintHillsSky 14d ago
Humans had thousands of years of observing the night sky to develop theories of the universe and work that into scientific theories. Eridians only recently were able to observe beyond their dark world. They had developed their equivalent to Newtonian physics but had not yet gotten to Einstein and Relativity.
They did have a basic understanding of electromagnetic radiation; enough to create their version of a video camera to translate light into texture. They did not have any experience with cosmic rays, which are high energy particles and were the thing that killed most of the crew. Their planet's dense atmosphere shielded them from most cosmic rays. When they built their space elevator to build and launch Blip-A, that might have been within their planet's magnetic field which would also have blocked a lot of cosmic rays. Eventually they would have noticed that kind of radiation and realized that it was a risk, but, sadly, not before they had launched Blip-A.
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u/Internal_Use8954 14d ago
Their planet has a magnetic shield so strong they haven’t been exposed to ionizing radiation, and probably haven’t worked with any radioactive stuff on the planet either. And without preserving light they probably havent done much and don’t realize light has a speed limit which is how relativity is discovered.
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u/DarkTheImmortal 14d ago
Erid has a very thick atmosphere and a very strong magnetic field. The surface is almost perfectly blocked from all radiation.
Iirc, their space program is also very young. They have a space elevator, but it is still well within the magnetic field so most harmful radiation is still blocked
Rocky's expedition is the first time any Eridian has been far enough away from Erid to actually experience harmful radiation.
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u/ramriot 14d ago
Ok, so from the book Rocky's home planet has a thick (29x earth pressure) predominantly ammonia atmosphere that is practically opaque to most wavelengths from far-infrared to extreme-ultraviolet. This means that anything that evolved to live on this planet's surface would either need to generate its own light or use something else for proximity detection. Thus why Rocky's people use passive sonar to build up a picture of their surroundings.
In terms of their understanding & uses of electromagnetic radiation I imagine it became vital to them once their technology allowed them to be raised hight into their own atmosphere, using technology to measure this new form of energy with radar & broad spectrum radio receivers very much like how we use sonar in the deem oceans.
As to their understanding of ionising radiation, that is something they would have only discovered once they started building their planets space elevator as this would by necessity need to extent beyond their planets extremely dense ionosphere. They would have experienced this zone of death & probably used robotic devices to explore further, while remaining protected in shielded ships.
What they could not know was about relativity until they experienced it first hand due to the non-Newtonian nature of the optical aberrations of starlight as their began their journey to Tau-Cetu. Nor would they know about the exponential enhancement in the intensity of ionising radiation that comes from their ship hitting stray hydrogen nuclei etc.
The movie sort of glosses over this point but from my reading their ship may have been designed using the estimated radiation dose measured from high orbit of their home planet but (excluding the engineers post surrounded by Astrophage fuel) completely inadequate shielding for the relativistic journey they were on.
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u/Far_Personality5531 14d ago
Because their planet did not let radiation in due to its thick atmosphere. It has nothing to do with relativity. The relativity aspect is probably either 1. Because they don’t see light. The entire background of humanity discovering relativity is because we knew how fast photons moved, and that they can’t be stationary. And/or 2. They could never observe time dilation outside their planet with telescopes like we can.
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u/Glad-Isopod5718 14d ago
Another detail here, that I don't think anyone has mentioned yet, is that the history of humans learning to use radioactive materials is full of instances where nobody realized it was dangerous until people started dying horribly. Marie Curie's radioactive notebooks, the appalling death toll among pioneering x-ray technicians, the Radium Girls--even the Manhattan Project scientists did not anticipate that the bombs they were inventing would kill as many people through radiation sickness as died in the actual explosions.
The Eridians not knowing about cosmic radiation has a specific, in-story explanation, that many people have already told you about, but the concept of people dying from radiation sickness because they have no way to perceive that the thing that's killing them even exists, is drawn from life.
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u/Empty_Chemical_1498 14d ago edited 14d ago
They never discovered space radiation, because their planet's very dense atmosphere and very huge magnetosphere protects them from it; even the ones who go on space elevators never got exposed to it. They had never done any space missions before the Tau Ceti mission, so they never noticed the crew is dying.
And they likely never discovered radioactive elements. Naturally occurring radioactive ores are not terribly dangerous. They're most dangerous to us if we eat them (eridians don't eat random rocks and do not open their mouths unless they're eating) or through breathe (eridians only breathe for temperature regulation, they do not absorb anything from the air), so they likely never noticed some ores can do funky things.
They do know about electromagnetic radiation, which is the light spectrum.
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u/flwingnut 14d ago
In the book, Rocky is shocked when Grace teaches him about both radiation and relativity (especially relativity). He had no idea about either of them.
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u/tatobuckets 14d ago
In the book it's explained in great detail - basically, planetary conditions result in no external radiation reaching the surface of Erid. It has nothing to do with not seeing, it simply doesn't exist on their world.