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Assume a human in direct vicinity (think 1-50 m [if you need more space for your intended device]) to the explosion center of a nuclear fusion bomb. Is survival via technology thinkable?

  • The TNT equivalent of this explosion is 6000 Megatons * (1 + your intended distance of human to explosion center squared)
    [EDIT: Does the explosion force matter here? I just wanted to imply a proper h-bomb. If it is important to your answer, you may reduce the force or just assume a tsar bomba]

  • Big Toolbox: This is not about today's technology but about if survival (and intact body) are at all possible from a physics standpoint. So even if you would need the ressources of a whole galaxy to achieve it, and ultra-advanced (but still extrapolated and non-magical) technology, the answer would still be valid.

  • I know we can not know exactly what we still don't know. Please do your best to extrapolate.

  • The lucky human entity has no special adaptions unless those are part of the answer. [EDIT: Everything within the confines above is ok, thanks for the hint]

If somebody wants to redirect me to general physics exchange, please do not. I have very carefully considered that this stack exchange is the place to ask.

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    $\begingroup$ That's 6 Gigatonnes right? 60 times the theoretical maximum output of Tsar Bomba? Just so I'm on the right scale here. Also where is this because in atmosphere versus in vacuum have very different considerations. $\endgroup$
    – Ash
    Commented Jun 18, 2018 at 18:51
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    $\begingroup$ You may consider [science-based] or [hard-science]. $\endgroup$
    – user25818
    Commented Jun 18, 2018 at 18:54
  • $\begingroup$ yes, the explosion energy matters (see table in my answer) $\endgroup$
    – L.Dutch ♦
    Commented Jun 18, 2018 at 19:03
  • $\begingroup$ My recommendation: a vessel with an insane quantity of radiation shielding and an insane rate of acceleration. A good deal of that explosion's energy is in the blast wave, so best outrun that. As for the pancake, er, person in the vessel, have them frozen to a few millikelvin above absolute zero the instant the bomb detonates and fill the air surrounding the person with something to keep them sturdy against the acceleration, like carbon nanotubes or something, then wire the tubes throughout every cell of the person. Like a supporting seatbelt for every cell. $\endgroup$
    – user44399
    Commented Jun 18, 2018 at 23:14
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    $\begingroup$ 6000 megatons is a bit much, but I used to work in a building designed to survive the nearby explosion of a '50s-era Soviet nuke: unr.edu/physics/ntf/about/sage-building $\endgroup$
    – jamesqf
    Commented Jun 19, 2018 at 6:17

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Nope.

The annihilation radius of a megaton bomb is several hundreds of meters. By "annihilation radius" I mean the spherical volume inside which everything is heated to 5000ºC or more, which would melt any material known.

Even if you find some material which doesn't get vapourized instantly by the heat, it has to sustain the blow. The hardest steel is like butter when white-hot, so you need a material that not only doesn't melt, but also doesn't lose its strength when heated to extreme temperatures - hard vacuum can help here by not producing a shockwave except from your own vehicle being vapourized, which let's pretend doesn't happen.

Even if you find some unobtanium which is able to resist all that heat, gamma-rays can easily get through hundreds of meters of insulation. Even if the shield blocks nearly all of the radiation, you are so close to an explosion so big that the radiation which passes through is enough to make your atmosphere burn - I'm not even mentioning the amount of sieverts your body is going to take. "Overkill" doesn't really express the amount of radiation is going to hit the poor guy.

Even if you find some really unobtainable unobtanium lined with handwavium to prevent radiation sickness, you have to deal with secondary radiation, since you know, unobtanium is really dense and the gamma-ray has turned its atoms into radiactive unobtanium isotopes, also known as kryptonite. Your vessel is now a radioactive dumpster. You are inside.

And then there's the biggest problem of all. The unobtanium layer you need to survive the explosion is 100 meters thick, which totally precludes the possibility of being just 50 meters away from the bomb. :p

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  • $\begingroup$ Thanks! Maybe the application of "forcefields" or conceivable shielding technology is viable? Or would you deem this impossible? $\endgroup$
    – user6415
    Commented Jun 19, 2018 at 16:03
  • $\begingroup$ @openend Forcefields would be the option I would go if I needed to make this story work - it's total handwave, but you can deflect all the questions about materials. The problem with forcefields is that they don't exist, and even if they did you would need a forcefield as strong as the explosion you want to resist. A 6 Gigaton bomb is way over the top, but a power source capable of sustain a 6 Gigaton forcefield is bordering the ridiculous. What magnitude would be its power output? Exawatts? $\endgroup$
    – Rekesoft
    Commented Jun 20, 2018 at 7:23
  • $\begingroup$ Well, if a magnetic or any other directed field of energy is capable of achieving the protection wanted, no matter the ressource (within the bounds stated) it would answer the question. $\endgroup$
    – user6415
    Commented Jun 20, 2018 at 18:09
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An underground exploding nuke, much smaller than the one you have in your question, reduces to plasma a sphere of several meters of rock.

table nuke explosion

The energy of the nuclear explosion is released in one microsecond. In the following few microseconds, the test hardware and surrounding rock are vaporised, with temperatures of several million degrees and pressures of several million atmospheres. Within milliseconds, a bubble of high-pressure gas and steam is formed. The heat and expanding shock wave cause the surrounding rock to vaporise, or be melted further away, creating a melt cavity.

The shock-induced motion and high internal pressure cause this cavity to expand outwards, which continues over several tenths of a second until the pressure has fallen sufficiently, to a level roughly comparable with the weight of the rock above, and can no longer grow.

There is no way you can keep something solid, let alone alive, so close to a nuclear explosion.

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I don't know about your 50m distance, but in general I think you could survive a lot closer than the other posters seem to think.

Consider an Orion drive, aka Nuclear Pulse Propulsion. Take the old cartoon thing of the guy who puts a stick of dynamite under something, sits on it and uses it as propulsion and turn it up to 11. Replace the dynamite with a nuclear device. Build a big, strong plate with very good shock absorbers. Once the impulse from the bomb has dissipated toss another one.

It was under serious consideration until they scrapped aboveground atomic testing. Test payloads very close to the detonation point were thrown clear with very minimal damage. (One chemical version was actually flown successfully, albeit not very far due to the inefficiency. Nuclear testing involved packages placed near weapons tests.)

Now, as Ash says, the acceleration would be deadly--but does it have to be? With an Orion type setup it certainly would be. However, what if the bomb is above you? It's trying to push you down into the ground and you're not going to go very far that way.

Thus my proposal is an inner shock absorber system, surrounded by a very thick sphere of iron foam.

The thermal pulse will convert the very surface to plasma and then mostly be directed away. The radiation will be absorbed. This leaves the blast wave--but there actually won't be that much because you're close in, little air between you and the bomb.

Since the material is foam what blast does hit it will mostly be expended crushing the foam rather than transmitted through to your hero.

This requires near future tech. Metal foam can only be produced in free fall.

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    $\begingroup$ The bombs of the Orion drive were tiny, carefully designed not to destroy the plates. $\endgroup$
    – Rekesoft
    Commented Jun 19, 2018 at 9:20
  • $\begingroup$ "This requires near future tech. Metal foam can only be produced in free fall." - This is doubtful. Wikipedia has an article on metal foam and does not mention free fall as a necessery prerequisite for manufacturing. As far as I understand the article, metal foam is already manufactured on an industrial basis: en.wikipedia.org/wiki/Metal_foam $\endgroup$
    – DerGreif
    Commented Jun 19, 2018 at 12:41
  • $\begingroup$ @Rekesoft In this case we can accept quite a bit of destruction. $\endgroup$
    – Loren Pechtel
    Commented Jun 19, 2018 at 18:31
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    $\begingroup$ @DerGreif What you're referring to is a crude version of what I'm talking about. Much smaller pores. $\endgroup$
    – Loren Pechtel
    Commented Jun 19, 2018 at 18:33
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    $\begingroup$ Project Orion was planning to use nukes with a yield of somewhere around 0.35 kilotons at most, while this question specifies 6000 MEGAtons. That's 17 million times bigger, which is about equal to the difference between a firecracker (100 J) and a Tomahawk cruise missile (1.9 * 10^9 J, 19 million times bigger). I can make a container that protects me from a firecracker easily. I can't do that for a Tomahawk missile. $\endgroup$
    – Ambrose Winters
    Commented Jun 21, 2018 at 17:58
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In an atmosphere the passenger of any survival vessel is plain and simply dead from the acceleration imparted to the vessel by the shock wave, that assumes the vessel isn't flattened outright by said shock, or vapourised by the fireball. Out in space hard vacuum becomes your friend, you still need a vessel that can survive the radiant blast but there is no shock wave to speak of in space. A combination of heavy radiation shielding material and sacrificial layers designed to vapourise as they absorb the radiant output should get you through. You're still talking about a shell that's metres thick made of layers of specialised materials and weighing tonnes per person.

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  • $\begingroup$ So to survive in atmosphere, the vessel must have a mechanism to evacuate the atmosphere in a large radius. Not sure what could create a giant pocket of void like that, but it should be less improbable than something able to withstand a 6000 Mt plasma ball. $\endgroup$
    – Eth
    Commented Jun 19, 2018 at 17:07
  • $\begingroup$ @Eth No, to survive in an atmosphere it has to be not close to the blast, period. $\endgroup$
    – Ash
    Commented Jun 19, 2018 at 17:10
  • $\begingroup$ Hence the solution to remove the local atmosphere $\endgroup$
    – Eth
    Commented Jun 20, 2018 at 11:09
  • $\begingroup$ @Eth Nope, you just couldn't do it, and even if you did the ground surge would kill you anyway, you can't get way with this on the surface of a planet, and if you're off the surface by enough to make a difference the fall will kill you, too much radiant heat for a parachute. $\endgroup$
    – Ash
    Commented Jun 20, 2018 at 11:15
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To survive this, you must be an AI who constantly uploads the latest version of his brain contents to a remotely located machine. The explosion will instantly vaporize you, but once the uploads stop, that will trigger the machine to load a new machine with your brain content. To you, this will feel like being instantly teleported away from the blast location, before that blast actually happened.

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  • $\begingroup$ Great idea. This does violate the "unharmed body" condition. $\endgroup$
    – user6415
    Commented Jun 20, 2018 at 18:06
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Not on your life!

Conditions in the "Pikadon" are basically the Sun's, and extremely violent. Only fictional metals like Adamantium could withstand that level of destruction.

Plus, the weapon you just described in your question is 120 times more poweful than man's most powerful H-bomb, the "Tsar" bomb.

I highly suggest your hero can either teleport fast or be one heck of a powerful wizard!

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