Another light question

[majornature]

Now correct me if i'm wrong... space is a vacuum. The speed of light is 3 * 10^8m/s in a vacuum. Correct?<br /><br />Light is energy. Correct?<br /><br />I know it may sound confusing... Earth is an object that orbits around the sun in the vacuum of space.<br /><br />So my question is:<br /><br />If nothing can travel faster than the speed of light in a vacuum, can some unknown force be faster than the speed of light in planetary conditions? <br /><br />I know it's awkward but this is just pounding my head.<br /><br />Could light be slowed down when absorb when it pass through planet? <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>

 

[billslugg]

It is true that nothing can travel faster than light in a vacuum.<br /><br />Light can be slowed down almost to a stop by various methods. In that case, even sound will travel faster than light. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[search]

<font color="yellow">Light can be slowed down almost to a stop by various methods. In that case, even sound will travel faster than light.</font><br /><br />Can you explain this sentence?

 

[billslugg]

Look here for an experiment where light was slowed down to 38 miles per hour. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[docm]

[grossly simplified]<br /><br />Light propagates through matter by its electromagnetic field creating <font color="yellow"><i>phonons</i></font>in the media (similar to a resonance). The photons and phonons mix forming a <font color="yellow"><i>polariton</i></font>/i> (a quasi-particle), which has a non-zero effective mass and therefore cannot travel at C. The exact polariton velocity depends on the lights frequency and the material.<br /><br />The light exits the other side much later than identical light that traveled the same distance through air or a vacuum.<br /><br />Example;<br /><br />Speed of light in a vacuum: 299,792.458 km/s<br />Speed of light in a diamond: 124,000 km/s<br /><br />Note that this is C for <i>individual photons.</i> The <i>group velocity</i> of light can be much higher; 300C through cesium atoms in a recent experiment.<br /><br />This would be akin to waves washing up on shore. When the angle between a wave and the shoreline is particularly acute the breakers travel along the wave's length faster than the wave's movement inland. <div class="Discussion_UserSignature"> </div>

 

[lukman]

Hmm, at 38mph, yes, i travel faster than that light, every day. <div class="Discussion_UserSignature"> </div>

 

[derekmcd]

<i>If nothing can travel faster than the speed of light in a vacuum, can some unknown force be faster than the speed of light in planetary conditions?</i><br /><br />Actually, the correct way to state your question would be to replace "travel" with "accelerate". <br /><br />Nothing can accelerate beyond C. However, there is the hypothetical partical called a Tachyon that has been proposed to "travel" at superluminal speeds. It's beyond me how they could exist, but in order to exist they would have to come into existence already travelling beyond C.<br /><br />I'm not sure what you mean by "planetary conditions". The accelerating expansion of the universe creates situations where to objects are moving away from each other faster than C, but to a stationary observer, neither is beyond C. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[lukman]

True, but anything beyond C is not visible, or not at our dimension, so no way to prove, point less. <div class="Discussion_UserSignature"> </div>

 

[derekmcd]

That certainly doesn't mean we cant detect one should they exist. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[dragon04]

<font color="yellow">That certainly doesn't mean we cant detect one should they exist.</font><br /><br />It would be at the extreme microscopic (quantum) level if we did. And certainly not at the atomic, molecular or larger frames of reference.<br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[majornature]

All of your answers are helpful. I have some understanding of it. <br /><br />So in our 3 dimensions (possibly 4 dimensions), C remain constant. <br /><br />What about in other dimensions? Has there been any scientifical experiment to prove the C is not constant in higher dimensions?<br /><br />I hope this is not too challenging of a question. <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>

 

[majornature]

I knew it. So it can be slowed down!! Wow! incredible!<br /><br />Thanks for the link billslugg!! <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>

 

[derekmcd]

I agree 100% it would be at the quantum level. At our current tech. level, this is not very difficult. Heck... we detect neutrinos all the time. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[derekmcd]

"<i>I knew it. So it can be slowed down!! Wow! incredible!</i>"<br /><br />Technically, no we can not slow down the speed of the photon. What happens is the atom absorbs the photon and the energy is increased in said atom. The atom then loses energy and emits a new identical photon which then continues to travel at C. What you witness in real time is the delay in which the photon is absorbed and released. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[majornature]

That still doesn't answer my question about light traveling or "accelerating" at a constant in higher dimensions.<br /><br /><br />What about the higher dimensions? Can light accelerate or travel at a constant speed in higher dimensions as it is assumed in our present dimensions?<br /> <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>

 

[lukman]

Do you mean if light behave the way it is at higher dimension or if light is not exist at all? maybe yes, maybe no, how to observe the higher dimension? Just like if snail at higher dimension can run faster or not exist at all. <div class="Discussion_UserSignature"> </div>

 

[majornature]

This topic is sitting in the back burner when it should be up front and center like the string theory!! <br /><br /> <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>

 

[docm]

In a recent post I put up a link where a group had designed a quantum repeater for communications using entanglement. <br /><br />Another article said a few months ago entanglement was used to transmit the quantum state of a group of cesium atoms to another group at a distance.<br /><br />No wonder Einstein called it "spooky action at a distance". <div class="Discussion_UserSignature"> </div>

 

[theone]

absolutely yes it can be slowed down coz Einstein said that light moves slower near great mass because of gravity but in vacuum faster

 

[MeteorWayne]

That is not correct. Light moves at the same speed in a vaccuum, even near great mass, only it's path appears to change.<br />Traveling through substances slows light down. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>