 Why does Macklin have objections to going back?
But Macklin is exactly what we need for a quick, dramatic test. For the past seven years Macklin—who was the Advanced Studies Department of Firestone University—had been involved in devising a faster-than-light drive to help the Army reach Pluto and eventually the nearer stars. "No, Harold, it isn't," Macklin admitted. "I would have said the common cold," Macklin replied, "but I suppose from what you have said you mean headaches." "Aspirins would still be used to reduce fever and relieve muscular pains," Mitchell said. Unless we can produce quick, conclusive and dramatic proof of our studies we can get no more financial backing.
 He doesn't want to go back. He'd rather be "stupid" than having headaches and always worrying.
 He doesn't want to have to undergo another experiment.  He doesn't want to go back. He'd rather be "stupid" than having headaches and always worrying.  It's too risky to try the experiment again. He'd rather take his chances the way he is now.  He doesn't want to go back. In the state he's in, he's too "stupid" to realize the ramifications of what happened to him.