<p>Yes.  When a core collapse supernova happens, it takes a few hours for the shock wave to reach the surface and "break out" (when we first "see" it). Meanwhile, the neutrinos can escape nearly directly once they reach the top of the core.</p>

<p>Of course, as you wrote, photons travel slightly faster, so if the SN is far enough away, the photons might overtake these neutrinos.  However, I have not done the calculation to see if the universe is big enough.</p>

CC BY-SA 3.0
2016-03-30T04:18:07.653Z
Neutrons from such a supernova have been observed (2-3 hours before the photons) and the supernova SN 1987A was close-by in the Large Magellanic Cloud. This is well-known. See this wikipedia article https://en.wikipedia.org/wiki/SN_1987A .
Jack R. Woods
CC BY-SA 3.0
2016-03-30T08:54:28.343Z
We still cannot rule out that Neutrinos do in fact travel at the speed of light.
Dean
CC BY-SA 3.0
2016-03-31T15:59:25.207Z
Not so. We know neutrinos have mass because they oscillate between different species (ie they transform from one species to another, and this requires mass).  Since they have mass, special relativity forbids them from achieving light speed.
eshaya
CC BY-SA 3.0
2016-03-29T16:14:42.143Z
2016-03-29T16:14:42.143Z
eshaya
<p>Neutrino's are very small though they have mass. Because of that it is probably that the don't have a speed faster than photons.</p>

<p>But is it in all events, like supernova's or else events, where it is possible that we first receive their neutrino's instead of their light? </p>

<p>Perhaps gravity or other interactions could change something in their way to earth?</p>

CC BY-SA 3.0
2016-03-29T16:12:22.530Z
Supernovae are thought to emit neutrinos immediately, as the core collapses. Photons are emitted from the surface a short time after this. So, the neutrinos don't actually travel faster - they are just released first.
Andy
CC BY-SA 3.0
2016-03-29T16:41:17.243Z
Incidentally photons **might** move slower than neutrinos in reality, due to scattering on the way. Is this what your question is about? (I think there was a recent paper about this somewhere...)
Andy
CC BY-SA 3.0
2016-03-30T08:09:39.903Z
Ok, that is something interesting. And neutrino's aren't scattered because they are neutral?! And do they behave the same in curved spacetime, or is it also possible that the geodesic of neutrino's are 'shorter'?
Marijn 
CC BY-SA 3.0
2016-03-30T08:33:46.187Z
If you're interested in neutrino arrival times, have a look at Jack's answer and especially SN1987A. That's an example of this difference being noticed.
Andy
<universe>
Are there events in universe which we receive first from their neutrino's instead of their photons?
Marijn 
# Are there events in universe which we receive first from their neutrino's instead of their photons?

(Asked by: username_0 on 2016-03-29)

Neutrino's are very small though they have mass. Because of that it is probably that the don't have a speed faster than photons.

But is it in all events, like supernova's or else events, where it is possible that we first receive their neutrino's instead of their light?

Perhaps gravity or other interactions could change something in their way to earth?

**Tags:** universe
> **Comments:**
> **username_1**: Supernovae are thought to emit neutrinos immediately, as the core collapses. Photons are emitted from the surface a short time after this. So, the neutrinos don't actually travel faster - they are just released first.  
> **username_1**: Incidentally photons **might** move slower than neutrinos in reality, due to scattering on the way. Is this what your question is about? (I think there was a recent paper about this somewhere...)  
> **username_0**: Ok, that is something interesting. And neutrino's aren't scattered because they are neutral?! And do they behave the same in curved spacetime, or is it also possible that the geodesic of neutrino's are 'shorter'?  
> **username_1**: If you're interested in neutrino arrival times, have a look at Jack's answer and especially SN1987A. That's an example of this difference being noticed.  

---

## 1 answers

### Answer by username_2 on 2016-03-29. Score: 2

Yes. When a core collapse supernova happens, it takes a few hours for the shock wave to reach the surface and "break out" (when we first "see" it). Meanwhile, the neutrinos can escape nearly directly once they reach the top of the core.

Of course, as you wrote, photons travel slightly faster, so if the SN is far enough away, the photons might overtake these neutrinos. However, I have not done the calculation to see if the universe is big enough.

> **Comments:**
> **username_3**: Neutrons from such a supernova have been observed (2-3 hours before the photons) and the supernova SN 1987A was close-by in the Large Magellanic Cloud. This is well-known. See this wikipedia article https://en.wikipedia.org/wiki/SN_1987A .  
> **username_4**: We still cannot rule out that Neutrinos do in fact travel at the speed of light.  
> **username_2**: Not so. We know neutrinos have mass because they oscillate between different species (ie they transform from one species to another, and this requires mass).  Since they have mass, special relativity forbids them from achieving light speed.  

---

