What is another name for a "causal loop"?

Physics

2 answers:

OleMash [197]4 years ago

8 0

B I believe but hey we also have Google to double check

zvonat [6]4 years ago

4 0

The Bootstrap Paradox.
To quote Doctor Who's explanation of it-

"So there's this man, he has a time machine. Up and down history he goes, zip, zip, zip, zip, zip, getting into scrapes. Another thing he has is a a passion for the works of Ludwig van Beethoven. And one day he thinks, 'What's the point of having a time machine if you don't get to meet your heroes?' So off he goes to 18th century Germany, but he can't find Beethoven anywhere. No one's heard of him. Not even his family have any idea who the time traveller is talking about. Beethoven literally... doesn't exist. This didn't happen by the way. I've met Beethoven. Nice chap, very intense.

Loved an arm wrestle. No, this is called the 'bootstrap paradox'. Google it. The time traveller panics. He can't bear the thought of a world without the music of Beethoven. Luckily he brought all of his Beethoven sheet music for Ludwig to sign. So he copies out all the concertos and the symphonies, and he gets them published. He becomes Beethoven. And history continues with barely a feather ruffled. But my question is this - who put those notes and phrases together? Who really composed Beethoven's 5th?"

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How are gamma rays and microwaves similar

kompoz [17]

They are both electromagnetic waves

Explanation:

Electromagnetic waves are waves consisting of periodic oscillations of electric and magnetic fields. The fields oscillate in a plane perpendicular to the direction of motion the wave, so they are transverse waves.

Electromagnetic waves are the only type of waves able to travel in a vacuum. All electromagnetic waves travel in a vacuum at the same speed, known as the speed of light, equal to:

$c=3.0\cdot 10^8 m/s$

Electromagnetic waves are divided into 7 different types, depending on their wavelength and frequency. From the shortest to the longest wavelength (and so, from highest to lowest frequency, since frequency is inversely proportional to wavelength), we have:

Gamma rays

X rays

Ultraviolet

Visible light

Infrared radiation

Microwaves

Radio waves

So as we can see, both gamma rays and microwaves are types of electromagnetic waves. The difference between them is their different wavelength/frequency: in fact, the wavelength of gamma rays is extremently short (), while microwaves have longer wavelengths (at the order of the centimeter).