Why does light travel at light speed?

[Chronos]

Clarification for bob: if c had an infinite velocity in our reference frame, the universe we observe would instantly collapse. That is what the Maxwell equations demand, and what Einstein realized when he made 'the biggest mistake of his career' by adding the cosmological constant. That Einstein dude turned out to be pretty smart.

 

[Blueplanetbob]

I am a bit wary of a cosmological constant. First of all Einstein introduced it because he did not want an expanding universe, then he took it out, now its back again.
Could the electromagnetic force travel at any speed faster than light speed, say 200,000 mps and still keep within the parameters of the energy fluctuations allowed without destroying the balance of the universe?

 

[Nereid]

I am a bit wary of a cosmological constant. First of all Einstein introduced it because he did not want an expanding universe, then he took it out, now its back again.

Ah, but look at why it's now back! Because there are good observations which are consistent with cosmological models with this constant in them (OK, it's the other way round, but the observations are what triggered the renewed interest). Also note that it's only one proposed means of accounting for the observations ... you could make a case that it gets more attention than other means because of its pedigree (and you'd've been right in the first few years; now it's possible to argue that it does fit the data better than the alternatives ... stay tuned for another decade or three!)