The Main Thing Wrong with Ad Astra

Yesterday evening I took my two granddaughters to see the movie Ad Astra.

SPOILER ALERT: Almost everything that follows is one great big SPOILER! If you don't want a spoiler, STOP READING RIGHT NOW!

The worst thing about the movie is its premise: that the "surges" that are zapping all electrical systems on Earth and its Moon are being caused by antimatter released from an expedition to Neptune to look for intelligent alien life forms.

We can even make antimatter today. One atom at a time. So it would be hopelessly expensive today to make the gram quantities of antimatter that would be needed for fast travel within the solar system. Supposing that in the near future that is depicted it will be possible to make and store gram quantities of antimatter, it still will be enormously expensive, and the expedition would only take enough for propulsion.

Presumably, the "surges" are EMPs from nuclear explosions resulting from leaking antimatter falling into the atmosphere of Neptune. An EMP strong enough to affect the whole solar system would require an enormous nuclear explosion that consumes far more antimatter than the expedition would have on board. And with multiple surges (at least two in the movie), I need to assume that the explosion is on the other side of Neptune from the orbiting expedition spacecraft. Otherwise, the explosion would destroy the spacecraft. And the explosion would light up Neptune bright enough to be seen from Earth in the daytime, so that the source of the "surges" couldn't be kept secret like they want to do in the movie.

Then, early in the movie, one of the US Space Command generals says that the explosions that cause the surges threaten to destabilize the solar system and destroy all life on Earth. The only way that could happen is if the explosions destroy Neptune, and for that you would need a planetary-size mass of antimatter.

IMHO the producers changed the plot in the middle. The premise would have been more plausible if the expedition had encountered an intelligent alien life form that is sufficiently technologically advanced to make lots and lots of antimatter, and uses it to send scout probes around the Galaxy at relativistic speeds to identify and exterminate all other intelligent life forms. Then the movie can end with the hero and his father (the commander of the expedition) using the nuclear weapon that the hero conveniently has brought with him to destroy the alien probe before it can do any more damage, like in the movie Independence Day.

As long as I'm on the subject, the other problem with the movie, from a scientific point of view, is that the various spacewalks by the hero would be totally impossible under known laws of physics. But I loved the special effects, especially how they did weightlessness.