EXTRACT FOR
Planet Killers
(Sean Brandywine)

"I understand the math, Dr. Carlton.  What you are saying is that at speeds very close to the speed of light, the mass increases to a very large number."



"Couldn't have put it better myself.  And then it follows that multiplying the speed times the mass gives much a much higher number for the force of the explosion.  Much more."



The military mind is always quick to latch onto new weapons.  "Then what you have," General Smith said, "is a very effective bomb.  Makes nukes look like firecrackers."



"You got it, General.  Now back to our Moon Strike.  Either some race was trying to visit us and their ship never decelerated from near light speed, or you have a weapon deliberately fired at the earth.  I believe, gentleman, that this object, this relativistic bomb, was aimed at the earth.  Luckily it missed."



"Luckily!" cried General Smith.  "Blowing up our moon and killing millions.  Millions!"



Dr. Carlton looked at the general over the rim of his glasses.  "It could have been worse," he said simply and softly.



For a minute no one spoke as they imagined what would have happened had this object struck the Earth.



"Probably no less than the elimination of the entire human species," Dr. Carlton filled in for them.  "Save for a few of us who were off the Earth at the time."



"Why do you think it missed, Doctor?" asked the President.



"Probably difficulty in aiming.  You see, we can assume that this bomb started out as a starship.  It left some planetary system, accelerating as rapidly as it could, probably ejecting massive amounts of reaction mass.  For a long time, it accelerated, maybe a year or two.  Then, when it was traveling at almost the speed of light, it traversed the space between their star system and ours.  As it neared our system, it was traveling at full speed, nearly c.  At that speed you can't change course.  You're covering 300,000 kilometers every second.  That's 186,000 miles.  Every second.  Something going that fast cannot have its course changed easily.  This means that they have to be very careful in their aim when the ship is traveling slowly enough to still change its course.  They could only make course changes while very far away from our solar system.  I think they simply missed."



"My God!" said the President softly.  He covered his face with his hands.  Dr. Carlton watched with interest.  He was good an explaining things but in this case he was glad that he did not have to make the decisions.



"Mr. President.  We have to retaliate," said General Smith.



"How?  Build a relativistic bomb ourselves?  Hell, we don't even know who launched this thing!"



"I believe we may be able to backtrack it," said Dr. Carlton.  "We have this photo," he said with a wave towards the display still on the screen.  "And, now that we know what to look for, there may be other tracks we can find.  I'd say there is a good chance we can find out where it came from."



"Then I suggest we contact the other nations and prepare a fleet to go there," said General Smith.  "And kick their butts!"



The President only shook his head sadly.  "We have met three races in space.  All three have been friendly.  There are some who maintain that any race intelligent enough to discover interstellar drive is intelligent enough to understand the illogic of war.  Who could have done this?  Who wants the human race wiped out?"



No one had an answer for him.



For a long time these four men looked at each other, unable or unwilling to voice their thoughts right then.



Finally the President took in a deep breath.  He muttered, "How am I going to tell the public?"  Then, louder, "How do we keep people from panicking?  How can we tell them than some race out there has the ability to totally destroy the Earth in a second?  And they just tried!"



"And," added Dr. Carlton, "that another such bomb may be on its way as we speak."



The President turned pale.  It took several long seconds before he could speak again.  "General, you're going to get your wish.  I want you to head up a commission that will include all nations.  Explain the problem and ask them to help formulate a response.  An armed response."



"Yes, Sir!"



"Dr. Carlton, I want you to find out where these bastards live.  We're going to go visit them."