• Support PF! Buy your school textbooks, materials and every day products via PF Here!

Archived Question on light waves

ok, so I'm sitting in class one day, and my physics teacher is talking about light... and since we had just finished up a section on sound, I was wondering whether there is such an effect as a "light-boom"

that is to say, if we were to have a spaceship that could go exactly at the speed of light, and we attached a flashlight to the front of the ship, could we not cause the buildup of light rays much the same as we can with sound and airplanes? if so, couldn't we make a gigantic weapon with this? let's say that there's life on a planet near alpha centauri, and we go to war with them... couldn't we just send out a ship with a big flashlight on the front, cause the buildup of light particles over the span of 4.3 years, and then decelerate just before hitting the planet? 4.3 years of light would definitely do some amount of damage to their planet, even if it's just blinding everyone on the surface...

I asked my teacher this, and he said something to the effect of "no, because of time dialation." I realize his point, but that makes me wonder how the red shift works, if this doesn't...

sorry if I confused anyone, and if anyone knows why this can/can't occur, could you please do so? it's been bugging me.
 
28
7
ok, so I'm sitting in class one day, and my physics teacher is talking about light... and since we had just finished up a section on sound, I was wondering whether there is such an effect as a "light-boom"

that is to say, if we were to have a spaceship that could go exactly at the speed of light, and we attached a flashlight to the front of the ship, could we not cause the buildup of light rays much the same as we can with sound and airplanes? if so, couldn't we make a gigantic weapon with this? let's say that there's life on a planet near alpha centauri, and we go to war with them... couldn't we just send out a ship with a big flashlight on the front, cause the buildup of light particles over the span of 4.3 years, and then decelerate just before hitting the planet? 4.3 years of light would definitely do some amount of damage to their planet, even if it's just blinding everyone on the surface...

I asked my teacher this, and he said something to the effect of "no, because of time dialation." I realize his point, but that makes me wonder how the red shift works, if this doesn't...

sorry if I confused anyone, and if anyone knows why this can/can't occur, could you please do so? it's been bugging me.
The teacher is correct, this cannot happen. The speed of light is the same for all observers, so there is no possibility of a 'light-boom'.

This concept is explained here: http://newt.phys.unsw.edu.au/einsteinlight/jw/module3_weird_logic.htm

It also mentions time dilation, since that is how both observers measure the speed to be the same.
 
What about cerenkov radiation? Isn't that somewhat comparable to a "light boom" ?
 

Want to reply to this thread?

"Question on light waves" You must log in or register to reply here.

Related Threads for: Question on light waves

  • Posted
Replies
1
Views
453
  • Posted
Replies
2
Views
3K
Replies
2
Views
4K
Replies
9
Views
7K
Replies
1
Views
2K
Replies
1
Views
999
Replies
3
Views
661

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top