# Just out of curiosity.

1. Oct 31, 2008

### tribdog

Its Halloween, which got me thinking about bats and how they can fly around in the dark without hitting anything. what would happen if you put a big mirror in the cave with the bats? what does a mirror do to their sonar?

2. Oct 31, 2008

### mgb_phys

Reflect it in exactly the same way as a rock face would.
If you really want a laugh, but a bat in an anechoic chamber

3. Oct 31, 2008

### rootX

1) They emit sound waves
2) Sounds waves reflect back when they hit something (like mirror)
3) They detect the reflected sound waves and do some calculations to estimate the distance between them and the object in their path.

It always made me wonder that if bats are really good in math.

4. Oct 31, 2008

### tribdog

I've set up some surveyor's equipment and shot a laser at a mirror and it gives the distance to the mirror plus the distance to what ever is reflected in the mirror. I was just wondering if sound waves could be affected the same way. Guess not.

5. Oct 31, 2008

### mgb_phys

Yes they would - but thats the whole point the bat works on. You shoot a light pulse, measure the time and work out the distance. The bat does exactly the same with sound.

There is a problem with laser distance meters with a reflective target that the pulse can bounce of the target, hit something behind you, bounce back to the reflector and back to the instrument, that's why the laser is switchable between first/last hit mode (or cooperative target mode).

For the bat it's even worse since any solid surface is a mirror and the sound wave bounces of in a spreading wavefront. So they have to do some nifty signal processing and adjust the power and frequency of the pulses to elliminate false returns.
Ironically almost all the things bats do were separately invented to improve radar systems before anyone (or at least anyone working on radar) discovered that bats already did it.

6. Oct 31, 2008

### Proton Soup

maybe check out the Daredevil movie that was released a few years back. same idea as bats, applied to superhero.

7. Oct 31, 2008

### Staff: Mentor

Many years ago, the sound of something flying around the bedroom woke me up. At first, I thought - that's odd - birds don't fly at night. Then I realized it might be a bat, which I confirmed when I turned on the light. My wife woke up, freaked and told me to get rid of it.

So I went down to the garage to find the butterfly net, so I could catch it without harming it. By the time I returned to the bedroom, the bat had gone. I'm guessing it left the same way it got in - through a small gap in the window, which we had open.

8. Oct 31, 2008

### tribdog

I found out one cool thing about bats. If you go after them with a tennis racket they dodge it, but if you wait until they pass you can hit them from behind.

9. Oct 31, 2008

### Moonbear

Staff Emeritus
Here's another cool thing about bats...if you live in AZ and handle one, you can move to the head of the line to get rabies shots. Seriously, they're common carriers of rabies, so no touching!

10. Oct 31, 2008

### lisab

Staff Emeritus
My first thought, too, Monnie! We've had a few deaths here in Washington State due to rabies...people who caught it by shooing out bats from their homes. None of them reported being bitten. If I remember right, at least two swear they never had physical contact with the bat.

11. Nov 1, 2008

### tribdog

I was in a hotel once and I heard something at the window. I moved the curtain aside and something bit my hand. It turned out to be a bat. I had to get the rabies shots because the hotel let the bat go.

12. Nov 1, 2008

### Oerg

careful.. some bats have rabies

13. Nov 1, 2008

### TheStatutoryApe

Most bats actually use both visual and sonar. Very few use sonar primarily. So a mirror just might confuse them with mixed signals between senses.

14. Nov 1, 2008

### Moonbear

Staff Emeritus
Bat bites can be very tiny and unnoticeable. Of the rare cases of rabies in humans, that's a common source, the unrecognized bat bite.

There was a story in the news fairly recently of a whole classroom of school kids needing to get rabies shots after some dimwit of a parent brought a dead bat in for them to pass around for show and tell. Who does something like that? "Hey, here's this dead and decaying animal I found in the yard, wanna play with it kids?" :yuck:

15. Nov 1, 2008

### physics girl phd

That's a rather violent way to mess with them, don't you think?
Here's a more benevolent way to mess with them if they're in your locale: If it's the time of day they fly round (aka. dusk), you can throw something small high up in the air (a set of keys works great) and they often dive bomb for them.

16. Nov 1, 2008

### turbo

I often fly-fish at dusk when giant mayflies (we call them green drakes) emerge on trout ponds. My home-tied dry flies are real enough so that bats try to eat them. I take a thick pair of leather work gloves so that I can take the hooks out and release the bats - I have caught a few, though usually, when the get the fly off the water, and start to feel the weight of the leader and fly-line, they'll figure out something's wrong and release the fly.

17. Nov 1, 2008

### joeyar

Wouldn't it be more ironic if you went after them with a baseball 'bat'?

18. Nov 2, 2008

### tribdog

OH god. do we have to put up with bad puns just because it's time for funniest guru?

19. Nov 2, 2008

### youngoldman

That wasn't a bad pun, that was just pun-ishing.

20. Nov 2, 2008

### Moonbear

Staff Emeritus
No, I think that bad pun completely disqualified him from any chance of nomination for the funniest member award.