Podcaster: Steve Nerlich
Title: Dear Cheap Astronomy: #118: Reflections
Organization: Cheap Astronomy
Links: http://cheapastro.com
Description: Cheap Astronomy becomes self-absorbed and reflects on a hypothesis
Dear Cheap Astronomy – Selfies in space.
Buzz Aldrin claims to have taken the first selfie in space in 1966, where he fixed a Hasselblad camera on the hull on Gemini 12 and then leant back before triggering the camera. Later on, in 1969, Neil Armstrong took an accidental selfie – the only still photo of him on the Moon where he and his camera are reflected in Buzz Aldrin’s visor.
Dear Cheap Astronomy – Is Hawking Radiation real?
Long-term listeners are probably familiar with Cheap Astronomy’s tendency to go a bit ranty in the face of any unreasonable acceptance of cosmology hypotheses. So, for example, the Universe is not only expanding but that expansion is accelerating. Sounds extraordinary, but there’s sound observational evidence to back it up.
Bio: Cheap Astronomy offers an educational website where you’re only as cheap as the telescope you’re looking through.
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Transcript:
20250529-365DoA
Transcribed by TurboScribe.ai. Go Unlimited to remove this message.
Hi, this is Steve Nerlic.
Why, why, why, why, why, why, why, why, why, Cheap astronomy?
Yeah, why? And this is Dear Cheap Astronomy, Episode 118, Reflections. It’s been proposed that our ultimate role in the universe is to give the universe a capacity for self-awareness.
Well, probably not in any purposeful way, but it is a job we can do whether the universe wants it or not. But first, we have to deal with our own narcissistic tendencies to focus our attention on ourselves. Dear Cheap Astronomy, Selfies in Space Buzz Aldrin claims to have taken the first selfie in space in 1966, where he’d fixed a Hasselblad camera onto the hull of Gemini 12 and then just leant back before triggering the camera.
Later on in 1969, Neil Armstrong took an accidental selfie, the only still photo of him on the moon, where he and his camera are reflected in Buzz Aldrin’s visor. Indeed, helmet-visor reflection pictures are a bit of a thing. You can take a selfie of yourself against an interesting background and then also capture the foreground reflected in your helmet-visor.
And some of the older helmet-visor reflection pictures, including the accidental Neil Armstrong selfie, have been unwrapped, meaning the image that was captured on the concave surface of the visor has since been flattened out with imaging software so you can see that image in its original configuration. In reality, it’s a bit meh. To be sure, it’s technically challenging and historically significant, but those reflections were mostly low-res to start with, so even after the unwrapping, it still looks meh.
Anyhow, feel free to Google Buzz Aldrin visor unwrapped if you’re interested. And we do digress. This week’s question is really about robot selfies in space.
So firstly, brace yourselves for a shock, folks. All those fabulous NASA promotion shots of Cassini in orbit around Saturn or New Horizons flying past Pluto are just composites. The drawn image of a spacecraft against the real image of the planet it’s visiting, although sometimes even those are drawn too.
For example, promotional pictures of the Parker Solar Probe are always shown against an artistically enhanced red sun, since a blindingly white real sun just wouldn’t look as good. But of course, the best robot selfies of all have been taken by the Mars rovers. Spirit and Opportunity took photos of themselves from above using their mast-mounted cameras.
These selfies initially showed both rovers’ solar panels becoming increasingly dusty over time, but later being cleaned up a bit after a gust of wispy Martian wind. And the newer Curiosity and Perseverance rovers are able to do more interesting selfies using cameras on their mobile arm. So their selfies are either front or side views of the rover, and you get a nice panoramic view of the Martian landscape in the background.
The apparently invisible camera is achieved by the joining up of around 60 separate photos, where any parts of the rover that have been obscured by the camera arm in one shot are overlaid by another shot from a slightly different angle. Incidentally, there’s also a photo of the very first Mars rover, Sojourner, on Mars in 1977, although that was taken by a camera on the nearby Pathfinder lander. But alas, it’s not likely we’ll see selfies from interplanetary spacecraft any time soon.
There’s not a lot to be gained from visualising a spacecraft that flies through a vacuum. You might spot the odd micrometeorite dint and other surface degradation from cosmic rays and sunlight, but there’s not a lot you can do about such damage, even if you can see it. And putting a camera on a swivel mount just adds a potential point of failure to billion-dollar, decade-long missions.
For example, it wouldn’t have been a good look for NASA to have New Horizons’ camera stuck in selfie mode, as it did its one and only flyby of Pluto. On the bright side though, the recent uncrewed and hence robotic Artemis 1 mission to the Moon did manage to take some nice shots from its externally mounted cameras, which did capture large parts of the craft, along with the Earth and the Moon in the background. While the scientific and engineering benefits of having a spacecraft in shot are fairly low, those shots do manage to give you a feeling that we’ve really been there.
So, whenever it’s possible, and represents no major cost or risk to the mission, then it’s certainly worth doing.
[Speaker 3]
This is the middle bit.
[Speaker 1]
So, it does seem likely we will always place ourselves firmly in the frame of any observations we make about the wider universe. And just how much do we know about the wider universe? Well, it depends what you mean by know.
Dear Cheap Astronomy, Is Hawking Radiation Real? Long-term listeners are probably familiar with Cheap Astronomy’s tendency to go on a bit of a rant in the face of any unreasonable acceptance of cosmology hypotheses. So, for example, the universe is not only expanding, but that expansion is accelerating.
Sounds extraordinary, but there’s some sound observational evidence to back this up. Cosmologists are keen to explain why this happens, and the current working hypothesis is that it’s driven by a mysterious form of energy that doesn’t obey the laws of thermodynamics, and, so far, is completely undetectable. Despite that, if you follow the logic through, it turns out that this utterly inexplicable and undetectable stuff represents about 70% of the current universe’s energy mass contents.
So this sounds extraordinary, and there’s no observational evidence at all to back it up. That doesn’t mean it’s wrong, but it doesn’t mean it’s right either. It’s just the prevailing hypothesis we are running with at the moment.
So, is Hawking Radiation real? Well, it might be, but at the moment it’s best considered a clever and interesting idea that no one has found any definitive evidence for, or against. And that’s no criticism of the late Professor Hawking.
This is just science at work. People kick some ideas around, some get shot down quickly, and some don’t, and sometimes people run physical experiments to either prove or disprove one of these prevailing ideas. So, for example, the notion that time might run differently in different parts of the universe does seem pretty extraordinary, but all you have to do is fly clocks around at different altitudes to demonstrate that it’s really true.
There are a range of experiments that allegedly demonstrate the existence of Hawking Radiation, although these are based on black hole and event horizon analogies, which aren’t all that compelling as analogies really, given that real black holes involve some fairly extreme physics which can’t be readily replicated on Earth. Such analogous experimental setups might allow you to conclude that what you observed was consistent with the existence of Hawking Radiation, but you couldn’t really say Hawking Radiation was the only possible explanation for the thing you observed. The genuine detection of Hawking Radiation around black holes is unlikely to be achievable with existing technologies since any black hole undergoing accretion would already be radiating an overwhelming amount of conventional radiation.
Also, you would be unable to detect any degree of black hole mass loss due to Hawking Radiation since a black hole in this age of the universe absorbs more cosmic microwave background radiation, not to mention other radiation, than it would lose by Hawking Radiation. To recap, Professor Hawking proposed that virtual particles, which pop into existence and self-annihilate a moment later, might instead dissociate near a black hole’s event horizon such that one remains outside and the other is sucked inside where it then annihilates with something else within. So the universe gains a photon and the black hole loses a photon equivalent of its energy mass contents and the net result of all that is that over the course of a googolplex years or so, the black hole evaporates.
That process leads to the Black Hole Information Paradox. Supposedly, information is never really destroyed, just transformed. So you can throw an encyclopedia into a furnace and its information can still kind of sort of be found in the subsequent radiated heat and the ash.
But Hawking Radiation has no causal connection with what’s inside a black hole. It’s made up of photons that originated from outside of the event horizon, so all the information contained within the black hole just evaporates and is gone forever. Of course, one solution to this information paradox is that Hawking Radiation is just an interesting idea which doesn’t actually lead to black holes evaporating.
For now, we are running with Hawking Radiation as a current working hypothesis while we wait for more data to come in. So, is Hawking Radiation real? Maybe.
[Speaker 3]
This is the end bit.
[Speaker 1]
So, there you go. If our role is to generate self-awareness in the universe, we do have an inordinate focus upon ourselves as a part of it, but nonetheless we have still managed to build up a reasonable schematic of the universe’s size and time frame and bits and pieces of how and why things happen in it the way that they do. We’re certainly a long way from knowing everything, and whatever you might make of the whole dark matter, dark energy narrative, it probably is about right to say that we only know what 5% of the universe actually is.
But that’s it for another episode of Dear Cheap Astronomy. If you’ve got a space science question, or you just want to know everything, why not write to CheapAstro at gmail.com and we’ll tell you what 5% of it is and speculate wildly on the other 95%. Thanks for listening.
Steve Nerlich, Cheap Astronomy. You are listening to the 365 Days of Astronomy podcast. Cool.
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365 Days of Astronomy
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