Is there life elsewhere in the Universe??

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Mad Scientist
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#998264 3-Mar-2014 16:39

Ah yes. :)

Fred99

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#998278 3-Mar-2014 16:54

andrew027:
joker97: forgot to add. if anyone wants concrete layperson explanations on theoretical physics head straight to the library and get a book called

The Beginning of Time by Stephen Hawkings

I know Hawking did a lecture called The Beginning of Time in the late 1990s but I think the book you are referring to is A Brief History of Time. Of more relevance to this thread is his lecture called Life in the Universe.

Excellent - I was looking for that link. While looking, I came across this response:

Aliens, as perceived by Hawking
Could soon visit Earth for some gawking.
They might do good, but Oy!,
They might wish to destroy!
We'll more likely be bored by their talking.

(John Menninger, Ph.D., Department of Biology, University of Iowa -- with apologies to E. Lear)

Hawking's warning may be right. If "Kin Selection" extends to an inherent behaviour for us to act at least a little altruistically toward all life on Earth with which we share genes, then there's no reason why alien life visiting us should have any empathy with us at all - far less than we'd feel toward an ant. Our best hopes may be that either we're useful to them as a resource, or they are sufficiently curious to want to leave us alone, observe us, and see what happens.

bazzer

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#999977 6-Mar-2014 09:28

tdgeek: If you travelled a litte faster than the speed of light, you will be invisible. You will still be there, but the light from you, won't

You mean like how if you're travelling faster than the speed of sound, you can't hear or be heard? You're still there , but the sound from you isn't.

Made it awfully difficult to order the chicken or the fish on the Concorde, unless you knew sign language!

JWR

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#1000064 6-Mar-2014 11:57

bazzer:
tdgeek: If you travelled a litte faster than the speed of light, you will be invisible. You will still be there, but the light from you, won't

You mean like how if you're travelling faster than the speed of sound, you can't hear or be heard? You're still there , but the sound from you isn't.

Made it awfully difficult to order the chicken or the fish on the Concorde, unless you knew sign language!

First of all, according to Einstein, nothing can travel faster than light. So you can't say anything about observing a faster than light object.

Only an object with zero rest mass (e.g. a light particle = photon) can travel at the speed of light.

For any massive object, mass increases as you go faster. You have to apply more and more energy to increase speed. Eventually, you would have to convert the the whole Universe to energy to power your object. Even then, it would never reach the speed of light.

Viewing an object traveling near the speed of light is a different story.

To view an object, you have the see the light coming off it. The light coming off any object is still moving at the speed of light. Doesn't matter if its moving towards or away from you. Obviously, you can always see that in theory.

However, it then becomes a measurement problem.

If an object is moving away, its light will be red-shifted. That means lower and lower energy, as well as being pushed towards the radio wave end of the spectrum. The object gets harder and harder to detect.

The opposite happens if the object is moving towards us. The light becomes blue-shifted. i.e. higher and higher energy, higher frequency. That is harder to detect as well.

TwoSeven

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#1000112 6-Mar-2014 13:00

JWR:
bazzer:
tdgeek: If you travelled a litte faster than the speed of light, you will be invisible. You will still be there, but the light from you, won't

You mean like how if you're travelling faster than the speed of sound, you can't hear or be heard? You're still there , but the sound from you isn't.

Made it awfully difficult to order the chicken or the fish on the Concorde, unless you knew sign language!

First of all, according to Einstein, nothing can travel faster than light. So you can't say anything about observing a faster than light object.
.

I understand that light travels at different speed and slows down and speeds up - it is affected by gravity and other such things (the medium it is travelling through). Also, E=MC^2 refers to the maximum possible speed of light - not the actual speed. It is basically saying that if something has mass, it requires energy to get it moving - the faster it goes the more energy required. At the speed of light, the energy would be unrealistically high. Not everything has mass - so quite a few things travel at the speed of light.

The other thing is that things can 'appear' to move faster than the speed of light. For example, if you spin around holding a torch in a room, the light pattern in the wall would be moving faster than the end of the torch because it has more distance to travel. If you were to turn around at the speed of light - the light beam on the wall would appear to move faster but doesn't because the light partials can only travel at maximum speed = C.

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surfisup1000

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#1000190 6-Mar-2014 14:41

TwoSeven:
JWR:
bazzer:
tdgeek: If you travelled a litte faster than the speed of light, you will be invisible. You will still be there, but the light from you, won't

You mean like how if you're travelling faster than the speed of sound, you can't hear or be heard? You're still there , but the sound from you isn't.

Made it awfully difficult to order the chicken or the fish on the Concorde, unless you knew sign language!

First of all, according to Einstein, nothing can travel faster than light. So you can't say anything about observing a faster than light object.
.

I understand that light travels at different speed and slows down and speeds up - it is affected by gravity and other such things (the medium it is travelling through). Also, E=MC^2 refers to the maximum possible speed of light - not the actual speed. It is basically saying that if something has mass, it requires energy to get it moving - the faster it goes the more energy required. At the speed of light, the energy would be unrealistically high. Not everything has mass - so quite a few things travel at the speed of light.

The other thing is that things can 'appear' to move faster than the speed of light. For example, if you spin around holding a torch in a room, the light pattern in the wall would be moving faster than the end of the torch because it has more distance to travel. If you were to turn around at the speed of light - the light beam on the wall would appear to move faster but doesn't because the light partials can only travel at maximum speed = C.

light is not affected by gravity as such as it has no mass . Rather, it is affected by the curvature in space and time as opposed to gravity.

MikeB4

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#1000193 6-Mar-2014 14:44

surfisup1000:
TwoSeven:
JWR:
bazzer:
tdgeek: If you travelled a litte faster than the speed of light, you will be invisible. You will still be there, but the light from you, won't

You mean like how if you're travelling faster than the speed of sound, you can't hear or be heard? You're still there , but the sound from you isn't.

Made it awfully difficult to order the chicken or the fish on the Concorde, unless you knew sign language!

First of all, according to Einstein, nothing can travel faster than light. So you can't say anything about observing a faster than light object.
.

I understand that light travels at different speed and slows down and speeds up - it is affected by gravity and other such things (the medium it is travelling through). Also, E=MC^2 refers to the maximum possible speed of light - not the actual speed. It is basically saying that if something has mass, it requires energy to get it moving - the faster it goes the more energy required. At the speed of light, the energy would be unrealistically high. Not everything has mass - so quite a few things travel at the speed of light.

The other thing is that things can 'appear' to move faster than the speed of light. For example, if you spin around holding a torch in a room, the light pattern in the wall would be moving faster than the end of the torch because it has more distance to travel. If you were to turn around at the speed of light - the light beam on the wall would appear to move faster but doesn't because the light partials can only travel at maximum speed = C.

light is not affected by gravity as such as it has no mass . Rather, it is affected by the curvature in space and time as opposed to gravity.

what prevents light leaving a black hole?

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tdgeek

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#1000195 6-Mar-2014 14:46

KiwiNZ:
surfisup1000:
TwoSeven:
JWR:
bazzer:
tdgeek: If you travelled a litte faster than the speed of light, you will be invisible. You will still be there, but the light from you, won't

You mean like how if you're travelling faster than the speed of sound, you can't hear or be heard? You're still there , but the sound from you isn't.

Made it awfully difficult to order the chicken or the fish on the Concorde, unless you knew sign language!

First of all, according to Einstein, nothing can travel faster than light. So you can't say anything about observing a faster than light object.
.

I understand that light travels at different speed and slows down and speeds up - it is affected by gravity and other such things (the medium it is travelling through). Also, E=MC^2 refers to the maximum possible speed of light - not the actual speed. It is basically saying that if something has mass, it requires energy to get it moving - the faster it goes the more energy required. At the speed of light, the energy would be unrealistically high. Not everything has mass - so quite a few things travel at the speed of light.

The other thing is that things can 'appear' to move faster than the speed of light. For example, if you spin around holding a torch in a room, the light pattern in the wall would be moving faster than the end of the torch because it has more distance to travel. If you were to turn around at the speed of light - the light beam on the wall would appear to move faster but doesn't because the light partials can only travel at maximum speed = C.

light is not affected by gravity as such as it has no mass . Rather, it is affected by the curvature in space and time as opposed to gravity.

what prevents light leaving a black hole?

My first thought after reading Surf's post. Thats why the black hole is a black hole and not a hole, light cannot escape the gravity

MikeB4

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#1000196 6-Mar-2014 14:48

tdgeek:
KiwiNZ:
surfisup1000:
TwoSeven:
JWR:
bazzer:
tdgeek: If you travelled a litte faster than the speed of light, you will be invisible. You will still be there, but the light from you, won't

You mean like how if you're travelling faster than the speed of sound, you can't hear or be heard? You're still there , but the sound from you isn't.

Made it awfully difficult to order the chicken or the fish on the Concorde, unless you knew sign language!

First of all, according to Einstein, nothing can travel faster than light. So you can't say anything about observing a faster than light object.
.

I understand that light travels at different speed and slows down and speeds up - it is affected by gravity and other such things (the medium it is travelling through). Also, E=MC^2 refers to the maximum possible speed of light - not the actual speed. It is basically saying that if something has mass, it requires energy to get it moving - the faster it goes the more energy required. At the speed of light, the energy would be unrealistically high. Not everything has mass - so quite a few things travel at the speed of light.

The other thing is that things can 'appear' to move faster than the speed of light. For example, if you spin around holding a torch in a room, the light pattern in the wall would be moving faster than the end of the torch because it has more distance to travel. If you were to turn around at the speed of light - the light beam on the wall would appear to move faster but doesn't because the light partials can only travel at maximum speed = C.

light is not affected by gravity as such as it has no mass . Rather, it is affected by the curvature in space and time as opposed to gravity.

what prevents light leaving a black hole?

My first thought after reading Surf's post. Thats why the black hole is a black hole and not a hole, light cannot escape the gravity

yep

JWR

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#1000208 6-Mar-2014 15:07

surfisup1000:
TwoSeven:
JWR:
bazzer:
tdgeek: If you travelled a litte faster than the speed of light, you will be invisible. You will still be there, but the light from you, won't

You mean like how if you're travelling faster than the speed of sound, you can't hear or be heard? You're still there , but the sound from you isn't.

Made it awfully difficult to order the chicken or the fish on the Concorde, unless you knew sign language!

First of all, according to Einstein, nothing can travel faster than light. So you can't say anything about observing a faster than light object.
.

I understand that light travels at different speed and slows down and speeds up - it is affected by gravity and other such things (the medium it is travelling through). Also, E=MC^2 refers to the maximum possible speed of light - not the actual speed. It is basically saying that if something has mass, it requires energy to get it moving - the faster it goes the more energy required. At the speed of light, the energy would be unrealistically high. Not everything has mass - so quite a few things travel at the speed of light.

The other thing is that things can 'appear' to move faster than the speed of light. For example, if you spin around holding a torch in a room, the light pattern in the wall would be moving faster than the end of the torch because it has more distance to travel. If you were to turn around at the speed of light - the light beam on the wall would appear to move faster but doesn't because the light partials can only travel at maximum speed = C.

light is not affected by gravity as such as it has no mass . Rather, it is affected by the curvature in space and time as opposed to gravity.

In Einstein's General Theory of Relativity, gravity IS the curvature of space-time.

Also, light affects and is affected by gravity.

Athlonite

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#1000245 6-Mar-2014 16:20

only the path in which light takes is affected by gravity

JWR

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#1000266 6-Mar-2014 16:53

Athlonite: only the path in which light takes is affected by gravity

Light does cause gravity.

Ofcourse, there are no great gravitational blobs of light. Light doesn't clump together like matter does.

However, if you want to consider the curvature of the Universe, as a whole, then you need to take into account the the density of light/radiation.

Fred99

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#1000272 6-Mar-2014 17:04

Gravitational effect on light was predicted long before Einstein, and gravitational time dilation might not have otherwise been predicted, but could have been observed - if accurate enough clocks had existed. It's quite reasonable (IMO) to state that light is affected by gravity. Einstein tied this all together, and observation has proved him right.

A5X

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#1000389 6-Mar-2014 20:27

Yes I believe Dr Phil exists in a parallel universe.

JWR

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#1000451 7-Mar-2014 03:01

Fred99: Gravitational effect on light was predicted long before Einstein, and gravitational time dilation might not have otherwise been predicted, but could have been observed - if accurate enough clocks had existed. It's quite reasonable (IMO) to state that light is affected by gravity. Einstein tied this all together, and observation has proved him right.

I am certain that Einstein was the first to predict the way gravity and light affect each other. Also, Einstein was the first to predict that gravity affected time.

Perhaps, other people speculated.. I am not aware of that. But, they didn't predict.

Einstein's General Theory of Relativity, made those predictions and is backed by experiment.

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