Another light speed one. Hypothetically…

[wildwood]

I am still trying to get my head around this speed of light thingy.

One spaceship can travel at the SoL and goes to the Canis Major Dwarf Galaxy (25000 light years away). Counting onboard time, would it get there in 12500 L.Y. as it meets the light?

[vascop]

Naomi
The word theory in science has 2 meanings which are very different:

1. a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena; "theories can incorporate facts and laws and tested hypotheses"; "true in fact and theory"

2. hypothesis: a tentative insight into the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena; "a scientific hypothesis that survives experimental testing becomes a scientific theory"; "he proposed a fresh theory of alkalis that later was ...

The Theory of Relativity comes under definition 1.
So when you say "it's just a theory" you are assuming it comes under 2, which in the case of relativity is incorrect.
It is unfortunate that the word theory has these two almost contradictory meanings which leads to a lot of misunderstandings and also misuse of the word.

[sammmo]

i'm not saying they ar'nt galaxys or stars all i'm saying is that the scientists say these things but they don't actually know because nobodys has actually been out that far to actually say that the scientists were right in there theory.. If one day aliens landed and said "crickey that was hell of a job to get through that curtain" what would the scientists say then? Scientists can be wrong can't they?

[naomi24]

vascop, thank you, but I am aware of the two definitions. I know what I said and I meant what I said.

[Davethedog]

HaHa yes they can be wrong but thier not wrong in the case of galaxies and stars.

How old are you? 8

[vascop]

Naomi
It isn't just a theory.

[naomi24]

Sammmo, yes they can be wrong - but I strongly suspect they aren't wrong where this is concerned. I can't imagine what you think these things might be.

[naomi24]

vascop, no one has ever experienced travel at the speed of light. I meant what I said.

[sammmo]

what difference does age make? according to scientists if i went faster than the speed of light i'd get younger.. you don't have to be an old scientist to have opinions ..Or do you?

[vascop]

Naomi
It is not necessary to travel at the speed of light to verify the Theory of Relativity.

[vascop]

sammo
Science doesn't deal in opinions.

[sammmo]

so why is'nt it a fact of relativity?

[vascop]

Sammo
Sorry I don't understand your last post.

[Davethedog]

1) You cannot travel at the speed of light.

2) The theory of relativity is just that until it can be proved and it can't be and according to modern thinking it never can be.

3) The whole point of it is to think in the abstract. All parts of the theory relate to light from point of origin. The whole thing about ageing and the time never changing are to describe the theory it can't happen. As you travel with the light time at your point of origin is the same as it ever was. You can only be younger if you never return, because if you have gone an earth year when you get back you will be a year older.

It is all realtive and is designed to prove theoretical physics.

[sammmo]

so is the "theory of relativity" still a theory or is it now a fact?

[vascop]

The Theory of Relativity is a fact, since all the massive amount of experimental evidence supports it. Please read my post to Naomi above about the meanings of the word theory.

[chakka35]

I would not agree with you, vascop, about theories, All scientific principles, however long established, are theories. When a theory (such as evolution) makes a huge amount of sense, is supported by masses of evidence with not one piece of evidence counting against it, and with no rival theory anywhere in sight, then it is reasonable to treat it as fact. Otherwise we would never move forward.

I'm not sure that relativity is yet in that category, but that might be a measure of my ignorance.

[vascop]

To try and argue that relativity is just an idea is just as ridiculous as saying:

"There is an idea going round that this house brick I am holding will fall to the ground and break my toe if I leave go of it - but I don't believe it, I'll drop it and let's see who's right..."

Aaaaaaaaaaaaaaaaaaaaaargh!!!!!! Call 999!

[Davethedog]

The theory of relativity is under challenge by modern day physics thats a fact.

The theory is still that. As Chakka says until it is proven it remains theory, and it cannot be proven until we can travel at light speed.

[vascop]

Chakka
That's a philosophical point, but let's be practical. I agree with your position totally. Relativity IS in that category now.