I don't believe that. I'm sure there were some other scientific minds capable of rigging a foil to prevent detection.

9 seconds sound clip from the Robot Monster (1953) movie soundboard.

You can hear this line at 00:19:14.612 in the Blu-ray version of the movie.

Quote context

[...]

- Maybe we could kill him, huh, Pop?

- No, Johnny. The armies of the entire world tried and failed.

- We have thrown everything we had at him, but he's impervious.

- Unless we can find his weak spot.

- Could I have just a little water, Mom?

- Yes, dear.

- But why here? Why here?

- Perhaps we're the last people on earth, Dad. He senses our presence and keeps calculating closer and closer.

- I don't believe that. I'm sure there were some other scientific minds capable of rigging a foil to prevent detection.

- If we only could find a way, only one way of communication with each other.

- Do you think we still have a garrison on the space platform? Ro-Man hasn't destroyed that yet.

- Well... It could be. If we only could get through to them.

- But why should we succeed where others failed?

[...]